BUILT-IN ANTENNA OF WIRELESS COMMUNICATION TERMINAL

Abstract

 Dipole antenna 12 is constructed of rectangular-wave-shaped antenna elements and the rectangular-wave-shaped antenna elements are mounted in such a way that the longitudinal direction is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal. A signal received by dipole antenna 12 is sent to a transmission/reception circuit via balanced/unbalanced conversion circuit 13. Here, balanced/unbalanced conversion circuit 13 minimizes the current that flows into base plate 11, thus preventing the antenna operation by base plate 11.

Description

Technical Field

[0001] The present invention relates to an antenna used for radio equipment and portable terminals, etc.

Background Art

[0002] In recent years, more and more compact radio communication terminals are being promoted to improve portability. In line with this, there is also a demand for smaller built-in antennas used for radio communication terminals. As a conventional built-in antenna that meets this demand, a tabular reverse F-figured antenna is used. A conventional built-in antenna used for a radio communication terminal will be explained below.

[0003] FIG. 1 is a schematic diagram showing a configuration of a conventional built-in antenna used for a radio communication terminal. The components shown in the same figure are incorporated in a package of the radio communication terminal, but an overall view of the radio communication terminal will be omitted for brevity of explanations. As shown in the same figure, the conventional radio communication terminal is generally provided with base plate 1 and tabular reverse F-figured antenna 2. X, Y and Z denote the respective coordinate axes.

[0004] Furthermore, the conventional built-in antenna above is also used as a diversity antenna that responds to fluctuations in the reception electric field intensity due to multi-paths of radio waves. FIG.2 is a schematic diagram showing a configuration of a diversity antenna used for a conventional radio communication terminal. As shown in FIG.2, the conventional radio communication terminal is provided with mono-pole antenna 3 as an external antenna in addition to tabular reverse F-figured antenna 2. By carrying out diversity reception using the two antennas, tabular reverse F-figured antenna 2 which is an internal antenna and mono-pole antenna 3 which is an external antenna, it is possible to implement stable communication.

[0005] However, the tabular reverse F-figured antenna used for the conventional radio communication terminal operates as an exciter that excites base plate 1 rather than tabular reverse F-figured antenna 2 itself operates as an antenna. For this reason, an antenna current flows into base plate 1 and the base plate becomes dominant as the antenna. As a result, tabular reverse F-figured antenna 2 used for the conventional radio communication terminal has a problem that the gain deteriorates due to influences from the body of the user of the radio communication terminal above.

[0006] Here, a specific example of the reception characteristic of tabular reverse F-figured antenna 2 used for the conventional radio communication terminal will be explained with reference to FIG.3A and FIG.3B. FIG.3A and FIG.3B illustrate actual measured values of the reception characteristic of tabular reverse F-figured antenna 2 used for the conventional radio communication terminal. Suppose the size of base plate 1 is 120x36 mm and the frequency is 2180 MHz.

[0007] First, FIG.3A illustrates the reception characteristic of a horizontal plane (X-Y plane) of tabular reverse F-figured antenna 2 used for the conventional radio communication terminal in a free space. As shown in FIG.3A, since base plate 1 operates as an antenna, tabular reverse F-figured antenna 2 has almost no directivity.

[0008] On the other hand, FIG.3B illustrates the reception characteristic of a horizontal plane (X-Y plane) of tabular reverse F-figured antenna 2 used for the conventional radio communication terminal during a conversation. Here, suppose the radio communication terminal is used in a position as shown in FIG.5. That is, as shown in FIG.5, radio communication terminal 4 provided with tabular reverse F-figured antenna 2 and mono-pole antenna 3 is used by user 5 for a conversation.

[0009] As is apparent from FIG.3B, the gain of tabular reverse F-figured antenna 2 is decreasing during a conversation. From a comparison between FIG.3A and FIG.3B, it is clear that the decrease in the gain of tabular reverse F-figured antenna 2 is attributable to influences from the body, for example, blocking of radio waves by the head or hand of the user, etc.

[0010] Then, a specific example of an emission characteristic of tabular reverse F-figured antenna 2 used for the conventional radio communication terminal will be explained with reference to FIG.4A and FIG.4B. FIG.4A and FIG.4B illustrate actual measured values of the emission characteristic of tabular reverse F-figured antenna 2 used for the conventional radio communication terminal.

[0011] FIG.4A illustrates the emission characteristic of a horizontal plane (X-Y plane) of tabular reverse F-figured antenna 2 used for the conventional radio communication terminal in a free space. As shown in FIG.4A, since base plate 1 operates as an antenna, tabular reverse F-figured antenna 2 has almost no directivity.

[0012] On the other hand, FIG.4B illustrates the emission characteristic of a horizontal plane (X-Y plane) of tabular reverse F-figured antenna 2 used for the conventional radio communication terminal during a conversation. Here, suppose the radio communication terminal is used in a position as shown in FIG.5. As is apparent from FIG.4B, the gain of tabular reverse F-figured antenna 2 is decreasing during a conversation. From a comparison between FIG.4A and FIG.4B, it is clear that the decrease in the gain of tabular reverse F-figured antenna 2 is attributable to influences from the body, for example, blocking of radio waves by the head or hand of the user, etc.

[0013] As shown above, tabular reverse F-figured antenna 2 used for the conventional radio communication terminal has a problem that the gain deteriorates due to influences from the human body.

[0014] Furthermore, a diversity antenna used for the conventional radio communication terminal above also has a problem that the gain deteriorates due to influences from the human body when tabular reverse F-figured antenna 2 operates.

Disclosure of Invention

[0015] It is an object of the present invention to provide a small built-in antenna for a radio communication terminal with high gain and little susceptible to the human body.

[0016] This object of the present invention is attained by providing the radio communication terminal with a dipole antenna, supplying power to the dipole antenna via a balanced/unbalanced conversion circuit having an impedance conversion function so that the antenna has directivity opposite to the human body during a conversation.

[0017] Moreover, the object of the present invention is attained by providing a passive element in parallel to the axial direction of an antenna element making up a dipole antenna and adjusting the length in the axial direction of the antenna element making up the dipole antenna, length in the axial direction of the passive element and distance between the antenna element making up the dipole antenna and the passive element appropriately so that the antenna has directivity opposite to the human body during a conversation.

[0018] Furthermore, the object of the present invention is attained by providing a bar-shaped passive element in such a way that the axial direction of the passive element is quasi-parallel to the axial direction of the bar-shaped antenna element making up the dipole antenna, a reference plane formed by including the passive element and the antennal element making up the dipole antenna is provided in such a way as to intersect with the main plane of the radio communication terminal at right angles and directivity is formed in the direction along the reference plane and perpendicular to the main plane of the radio communication terminal.

[0019] Furthermore, the object of the present invention is attained by providing the loop plane of a loop antenna so as to intersect with the human body at quasi-right angles, providing the loop antenna in such a way that the circumference of the loop antenna is one wavelength or shorter and supplying power to the loop antenna via a balanced/unbalanced conversion circuit with an impedance conversion function.

Brief Description of Drawings

[0020] 

FIG. 1 is a schematic diagram showing a configuration of a built-in antenna used for a conventional radio communication terminal;

FIG.2 is a schematic diagram showing a configuration of a diversity antenna used for the conventional radio communication terminal;

FIG.3A illustrates a reception characteristic of a tabular reverse F-figured antenna used for the conventional radio communication terminal in a free space;

FIG.3B illustrates a reception characteristic of the tabular reverse F-figured antenna used for the conventional radio communication terminal during a conversation;

FIG.4A illustrates an emission characteristic of the tabular reverse F-figured antenna used for the conventional radio communication terminal in a free space;

FIG. 4B illustrates a emission characteristic of the tabular reverse F-figured antenna used for the conventional radio communication terminal during a conversation;

FIG.5 is a schematic diagram showing the conventional radio communication terminal during a conversation;

FIG.6 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 1 of the present invention;

FIG. 7 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 2 of the present invention;

FIG.8 illustrates actual measured values of the reception characteristic of the built-in antenna for a radio communication terminal according to Embodiment 1 of the present invention during a conversation;

FIG. 9 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 3 of the present invention;

FIG.10 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 4 of the present invention;

FIG.11 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 5 of the present invention;

FIG.12 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 6 of the present invention;

FIG.13 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 7 of the present invention;

FIG.14 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 8 of the present invention;

FIG.15 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 9 of the present invention;

FIG.16 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 10 of the present invention;

FIG.17 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 11 of the present invention;

FIG.18 is a schematic diagram showing a configuration of a folded-dipole antenna used for Embodiment 12 of the present invention;

FIG.19 is a schematic diagram showing a configuration of a folded-dipole antenna used for Embodiment 13 of the present invention;

FIG.20 is a schematic diagram showing a configuration of a dipole antenna used for Embodiment 14 of the present invention;

FIG.21 is a schematic diagram showing a configuration of a folded-dipole antenna used for Embodiment 15 of the present invention;

FIG.22 is a schematic diagram showing a configuration of a folded-dipole antenna used for Embodiment 16 of the present invention;

FIG.23 is a schematic diagram showing a configuration of a dipole antenna placed on circuit board 181 in Embodiment 17 of the present invention;

FIG.24 is a schematic diagram showing a configuration of a dipole antenna placed on package case 191 in Embodiment 18 of the present invention;

FIG.25 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 19 of the present invention;

FIG.26 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 20 of the present invention;

FIG.27 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 21 of the present invention;

FIG.28 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 22 of the present invention;

FIG.29 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 23 of the present invention;

FIG.30 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 24 of the present invention;

FIG.31 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 25 of the present invention;

FIG.32 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 26 of the present invention;

FIG.33 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 27 of the present invention;

FIG.34 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 28 of the present invention;

FIG.35 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 29 of the present invention;

FIG.36 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 30 of the present invention;

FIG.37 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 31 of the present invention;

FIG.38 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 32 of the present invention;

FIG.39 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 33 of the present invention;

FIG.40 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 34 of the present invention;

FIG.41 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 35 of the present invention;

FIG.42 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 36 of the present invention;

FIG.43 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 37 of the present invention;

FIG.44 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 38 of the present invention;

FIG.45 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 39 of the present invention;

FIG.46 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 40 of the present invention;

FIG.47 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 41 of the present invention;

FIG.48 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 42 of the present invention;

FIG.49 is a schematic diagram showing a configuration of a folded-dipole antenna used for Embodiment 43 of the present invention;

FIG.50 is a schematic diagram showing a configuration of a folded-dipole antenna used for Embodiment 44 of the present invention;

FIG.51 is a schematic diagram showing a configuration of a folded-dipole antenna used for Embodiment 45 of the present invention;

FIG.52 is a schematic diagram showing a configuration of a folded-dipole antenna used for Embodiment 46 of the present invention;

FIG.53 is a schematic diagram showing a configuration of a folded-dipole antenna used for Embodiment 47 of the present invention;

FIG.54 is a schematic diagram showing a configuration of a folded-dipole antenna used for Embodiment 48 of the present invention;

FIG.55 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 49 of the present invention;

FIG.56 is a front view showing an appearance of a communication terminal apparatus incorporating the built-in antenna for a radio communication terminal according to Embodiment 49 of the present invention;

FIG.57 is a cross-sectional view viewed from the direction of arrow A in FIG.50 of the built-in antenna for a radio communication terminal according to Embodiment 49 of the present invention;

FIG.58 is a schematic diagram showing the radio communication terminal apparatus incorporating the built-in antenna for a radio communication terminal according to Embodiment 49 of the present invention during a conversation;

FIG.59 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 50 of the present invention;

FIG.60 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 51 of the present invention;

FIG.61 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 52 of the present invention;

FIG.62 illustrates actual measured values of an emission characteristic of the built-in antenna for a radio communication terminal according to Embodiment 52 of the presenc invention in a free space;

FIG.63 illustrates actual measured values of an emission characteristic of the built-in antenna for a radio communication terminal according to Embodiment 52 of the present invention during a conversation;

FIG.64 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 53 of the present invention;

FIG.65 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 54 of the present invention;

FIG.66 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 55 of the present invention;

FIG.67 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 56 of the present invention;

FIG.68 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 57 of the present invention;

FIG.69 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 58 of the present invention;

FIG.70 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 59 of the present invention;

FIG.71 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 60 of the present invention;

FIG.72 illustrates actual measured values of a reception characteristic of the built-in antenna for a radio communication terminal according to Embodiment 60 of the present invention during a conversation;

FIG.73 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 61 of the present invention;

FIG.74 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 62 of the present invention;

FIG.75A is a schematic diagram showing a configuration of a first built-in antenna for a radio communication terminal according to Embodiment 63 of the present invention;

FIG.75B is a schematic diagram showing a configuration of a second built-in antenna for a radio communication terminal according to Embodiment 63 of the present invention;

FIG.76 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 64 of the present invention;

FIG.77 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 65 of the present invention;

FIG.78 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 66 of the present invention;

FIG.79 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 67 of the present invention;

FIG.80 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 68 of the present invention;

FIG.81 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 69 of the present invention; and

FIG.82 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 70 of the present invention.

Best Mode for Carrying out the Invention

[0021] With reference now to the attached drawings, embodiments of the present invention will be explained in detail below.

(Embodiment 1)

[0022] FIG. 6 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 1 of the present invention. The components shown in the same figure are mounted in a package of a radio communication terminal. An overall view of the radio communication terminal will be omitted for brevity of explanations. The radio communication terminal according to this embodiment is constructed of base plate 11, dipole antenna 12, balanced/unbalanced conversion circuit 13 and power supply terminals 14. Each component will be explained below.

[0023] Base plate 11 is a tabular grounded conductor and is attached in quasi-parallel to the plane (vertical plane) on which operation buttons, a display and speaker, etc. of the radio communication terminal, which are not shown in the figure, are provided.

[0024] Dipole antenna 12 is constructed of two rectangular-wave-shaped (comb-tooth-shaped) antenna elements. This miniaturizes the dipole antenna. The two antenna elements making up dipole antenna 12 are placed in such a way that their respective longitudinal directions form a quasi-straight line.

[0025] Dipole antenna 12 is mounted in such a way that the longitudinal directions of the antenna elements are quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal. As a result, dipole antenna 12 is provided in such a way that the longitudinal directions of the antenna elements are quasi-perpendicular to the horizontal plane. Thus, dipole antenna 12 mainly receives vertical polarized waves parallel to the longitudinal direction in a free space. Furthermore, since the human body acts as a reflector during a conversation, dipole antenna 12 has directivity opposite to the direction of the human body.

[0026] Balanced/unbalanced conversion circuit 13 is a conversion circuit with an impedance conversion ratio of 1 to 1 or n to 1 (n : integer) and is attached to power supply terminals 14 of dipole antenna 12. One terminal of balanced/unbalanced conversion circuit 13 is connected to a transmission/reception circuit, which is not shown. The other terminal is attached to base plate 11. In this way, balanced/unbalanced conversion circuit 13 performs impedance conversion between dipole antenna 12 and the transmission/reception circuit above, making it possible to obtain impedance matching between the two appropriately. Moreover, balanced/unbalanced conversion circuit 13 converts an unbalanced signal of the transmission/reception circuit above to a balanced signal and supplies the balanced signal to dipole antenna 12, and can thereby minimize the current that flows into base plate 11. This prevents the action of base plate 11 as an antenna, and can thereby suppress a drop of gain of dipole antenna 12 caused by influences from the human body.

[0027] Next, the operation of the built-in antenna for a radio communication terminal in the above configuration will be explained. An unbalanced signal from the transmission/reception circuit above is converted to a balanced signal by balanced/unbalanced conversion circuit 13 and then sent to dipole antenna 12. Dipole antenna 12 supplied with power in this way mainly sends vertical polarized waves parallel to this longitudinal direction. On the other hand, during reception, dipole antenna 12 receives vertical polarized waves parallel to the longitudinal direction above. Thus, vertical polarized waves from all directions centered on the dipole antenna are received in a free space and during a conversation, since the human body acts as a reflector as described above, of the vertical polarized waves above, those opposite to the human body are mainly received.

[0028] The signals above received by dipole antenna 12 (balanced signals) are sent to the transmission/reception circuit above via balanced/unbalanced conversion circuit 13. Since balanced/unbalanced conversion circuit 13 minimizes the current that flows into base plate 11, the antenna operation by base plate 11 is prevented. This minimizes reduction of the gain caused by influences from the human body.

[0029] Here, the reception characteristic of the built-in antenna for a radio communication terminal in the above configuration will be explained with reference to FIG.8. FIG. 8 illustrates actual measured values of the reception characteristic of the built-in antenna for a radio communication terminal according to this embodiment during a conversation. Suppose the size of base plate 1 is 120×36 mm, the size of dipole antenna 12 is 63×5 mm, the distance of dipole antenna 12 from the human body is 5 mm, and the frequency is 2180 MHz. In FIG.8, the direction at 270° from the origin corresponds to the direction of the human body viewed from dipole antenna 12 in FIG.6.

[0030] As is apparent from FIG.8, because of the influence from the human body that acts as a reflector, dipole antenna has directivity opposite to the direction of the human body. Moreover, any split of directivity is prevented for the above-described reason and a high gain characteristic with suppressed deterioration of gain is maintained compared to the conventional example shown in FIG.3B.

[0031] Thus, according to this embodiment, balanced/unbalanced conversion circuit 13 adjusts impedance appropriately and can thereby minimize the antenna current that flows into base plate 11 and suppress deterioration of gain of dipole antenna 12 caused by influences from the human body. Furthermore, since dipole antenna 12 is constructed of rectangular-wave-shaped antenna elements, it is possible to miniaturize the built-in antenna for a radio communication terminal. This makes it possible to provide a high gain and small built-in antenna for radio communication terminal with little influence from the human body.

(Embodiment 2)

[0032] Embodiment 2 is a mode in which the method of mounting dipole antenna 12 in Embodiment 1 is changed. Since Embodiment 2 is the same as Embodiment 1 except for the method of mounting dipole antenna 12, detailed explanations thereof will be omitted. Differences of the built-in antenna for a radio communication terminal according to this embodiment from Embodiment 1 will be explained below using FIG.7. The parts similar to those in Embodiment 1 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0033] FIG.7 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 2. As shown in this figure, the built-in antenna for a radio communication terminal according to Embodiment 2 is constructed of base plate 11, dipole antenna 12, balanced/unbalanced conversion circuit 13 and power supply terminals 14.

[0034] Dipole antenna 12 is mounted in such a way that the longitudinal directions of the antenna elements are quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal. That is, this embodiment is different from Embodiment 1 in that dipole antenna 12 is provided in such a way that the longitudinal directions of the antenna elements are quasi-parallel to the upper surface (horizontal plane).

[0035] This allows dipole antenna 12 to suppress deterioration of gain and mainly receive horizontal polarized waves parallel to the longitudinal direction. On the other hand, a signal sent from the other end of communication is a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, when there are more horizontal polarized waves, the longitudinal direction of the antenna matches the polarization plane, which makes it possible to increase the reception gain.

[0036] According to this embodiment, dipole antenna 12 is mounted in such a way that the longitudinal directions of the antenna elements are quasi-parallel to the upper surface of the radio communication terminal, which makes it possible to suppress deterioration of gain caused by influences from the human body and mainly receive horizontal polarized waves. This makes it possible to prevent deterioration of gain due to mismatch between the signal from the other end of communication and the polarization plane and provide a high gain and small built-in antenna for a radio communication terminal with little influence from the human body.

(Embodiment 3)

[0037] Embodiment 3 is a mode in which the configuration and method of mounting dipole antenna 12 in Embodiment 1 is changed. Since Embodiment 3 is the same as Embodiment 1 except for the configuration and method of mounting the dipole antenna, detailed explanations thereof will be omitted. Differences of the built-in antenna for a radio communication terminal according to this embodiment from Embodiment 1 will be explained below using FIG.9. The parts similar to those in Embodiment 1 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0038] FIG.9 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 3. As shown in this figure, the built-in antenna for a radio communication terminal according to Embodiment 3 is constructed of base plate 11, dipole antenna 41, balanced/unbalanced conversion circuit 13 and power supply terminals 14. The two antenna elements making up dipole antenna 41 are placed in such a way that the longitudinal directions are quasi-perpendicular to each other.

[0039] Dipole antenna 41 is mounted in such a way that the longitudinal direction of one antenna element is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal and the longitudinal direction of the other antenna element is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal.

[0040] Then, the operation of the built-in antenna for a radio communication terminal in the above configuration will be explained. An unbalanced signal from the transmission/reception circuit above is converted to a balanced signal by balanced/unbalanced conversion circuit 13 and then sent to dipole antenna 41. The antenna element placed quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal that makes up dipole antenna 41 supplied with power in this way mainly sends vertical polarized waves parallel to the longitudinal direction of this antenna element. Furthermore, during reception, vertical polarized waves parallel to the longitudinal direction above are received. On the other hand, the antenna element placed quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal that makes up dipole antenna 41 supplied with power in the same way mainly sends horizontal polarized waves parallel to the longitudinal direction of this antenna element. Furthermore, during reception, horizontal polarized waves parallel to the longitudinal direction above are received. In a free space, vertical and horizontal polarized waves from all directions centered on the dipole antenna are received. During a conversation, since the human body acts as a reflector as described above, of the vertical polarized waves and horizontal polarized waves above, the waves opposite to the human body are mainly received.

[0041] This allows dipole antenna 12 to suppress deterioration of gain and receive both vertical polarized waves and horizontal polarized waves parallel to the longitudinal direction. On the other hand, a signal sent from the other end of communication is a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, even if there are more vertical polarized waves or more horizontal polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the polarization plane of the signal sent from the other end of communication, allowing reception gain to be increased.

[0042] According to this embodiment, balanced/unbalanced conversion circuit 13 can minimize the antenna current that flows into base plate 11 and can thereby suppress deterioration of gain caused by influences from the human body. Furthermore, dipole antenna 41 is constructed of rectangular-wave-shaped antenna elements, making it possible to miniaturize the built-in antenna for a radio communication terminal and provide a high gain and small built-in antenna for a radio communication terminal with little influence from the human body.

(Embodiment 4)

[0043] Embodiment 4 is a mode in which the shape and method of mounting antenna elements making up dipole antenna 12 in Embodiment 1 are changed. Since Embodiment 4 is the same as Embodiment 1 except for the shape of the antenna elements and method of mounting the dipole antenna, detailed explanations thereof will be omitted. Differences of the built-in antenna for a radio communication terminal according to this embodiment from Embodiment 1 will be explained below using FIG.10. The parts similar to those in Embodiment 1 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0044] FIG.10 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 4. As shown in this figure, the built-in antenna for a radio communication terminal according to Embodiment 4 is constructed of base plate 11, dipole antenna 51, balanced/unbalanced conversion circuit 13 and power supply terminals 14. The antenna elements making up dipole antenna 51 are folded at a point close to the center and the folded planes are formed to be quasi-perpendicular to each other. In this case, of the planes quasi-perpendicular to each other of the antenna elements, the plane including power supply terminals 14 is called a "first rectangular-wave-shaped plane" and the other plane without power supply terminals 14 is called a "second rectangular-wave-shaped plane".

[0045] The antenna elements making up dipole antenna 51 in the above configuration are mounted in such a way that the longitudinal direction of the first rectangular-wave-shaped plane is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal apparatus and the longitudinal direction of the second rectangular-wave-shaped plane is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal apparatus.

[0046] That is, this embodiment is different from Embodiment 1 in that the longitudinal direction of the first rectangular-wave-shaped plane of dipole antenna 51 is quasi-parallel to the upper surface of the radio communication terminal apparatus and the longitudinal direction of the second rectangular-wave-shaped plane is quasi-perpendicular to the upper surface of the radio communication terminal apparatus . As a result, as in the case of Embodiment 1, dipole antenna 51 is provided during a conversation in such a way that the longitudinal direction of the first rectangular-wave-shaped plane above is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal and the longitudinal direction of the second rectangular-wave-shaped plane above is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal.

[0047] Thus, this embodiment configured as shown above can also attain effects similar to those of Embodiment 3.

(Embodiment 5)

[0048] Embodiment 5 to Embodiment 11 are modes in which a diversity antenna is implemented using the built-in antennas for a radio communication terminal according to Embodiment 1 to Embodiment 4.

[0049] Embodiment 5 is a mode in which a diversity antenna is implemented using the built-in antennas for a radio communication terminal according to Embodiment 1. The diversity antenna for a radio communication terminal according to this embodiment will be explained below using FIG.11. The parts similar to those in Embodiment 1 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0050] FIG.11 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 5. In FIG. 11, monopole antenna 61 is added to the configuration of the built-in antenna for a radio communication terminal according to Embodiment 1.

[0051] Here, suppose one antenna making up the diversity antenna is dipole antenna 12 in Embodiment 1 and used for reception only. Also suppose the other antenna making up the diversity antenna is monopole antenna 61 and used for both transmission and reception.

[0052] In the diversity antenna for a radio communication terminal in the above configuration, only monopole antenna 61 operates during transmission and dipole antenna 12 and monopole antenna 61 operate during reception to carry out diversity reception.

[0053] Thus, according to this embodiment, dipole antenna 12 in Embodiment 1 is used as the diversity antenna, which makes it possible to provide a high gain and small diversity antenna for a radio communication terminal with little influence from the human body as in the case of Embodiment 1.

(Embodiment 6)

[0054] Embodiment 6 is a mode in which the configuration of the monopole antenna in Embodiment 5 is changed. The diversity antenna for a radio communication terminal according to this embodiment will be explained using FIG.12. The same configurations as those in Embodiment 5 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0055] FIG.12 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 6. As shown in FIG.12, the diversity antenna for a radio communication terminal according to Embodiment 6 is constructed of dipole antenna 12, balanced/unbalanced conversion circuit 13, power supply terminals 14 and monopole antenna 71. Monopole antenna 71 is constructed of a rectangular-wave-shaped antenna element.

[0056] In the diversity antenna for a radio communication terminal in the above configuration, only monopole antenna 71 operates during transmission and dipole antenna 12 and monopole antenna 71 operate during reception to carry out diversity reception.

[0057] Thus, according to this embodiment, dipole antenna 12 in Embodiment 1 is used as the diversity antenna, which makes it possible to provide a high gain diversity antenna for a radio communication terminal with little influence from the human body. Furthermore, by providing rectangular-wave-shaped monopole antenna 71, it is possible to miniaturize the external antenna.

(Embodiment 7)

[0058] Embodiment 7 is a mode in which the configuration of the monopole antenna in Embodiment 5 is changed. The diversity antenna for a radio communication terminal according to this embodiment will be explained using FIG.13. The same configurations as those in Embodiment 5 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0059] FIG.13 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 7. As shown in this figure, the diversity antenna for a radio communication terminal according to Embodiment 7 is constructed of dipole antenna 12, balanced/unbalanced conversion circuit 13, power supply terminals 14 and monopole antenna 81. Monopole antenna 81 is constructed of a spiral antenna element.

[0060] In the diversity antenna for a radio communication terminal in the above configuration, only monopole antenna 81 operates during transmission and dipole antenna 12 and monopole antenna 81 operate during reception to carry out diversity reception.

[0061] Thus, this embodiment configured as shown above can also attain effects similar to those in Embodiment 6.

(Embodiment 8)

[0062] Embodiment 8 is a mode in which a diversity antenna is implemented using the built-in antenna for a radio communication terminal in Embodiment 1. The diversity antenna for a radio communication terminal according to this embodiment will be explained using FIG.14. The same configurations as those in Embodiment 1 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0063] FIG.14 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 8. As shown in this figure, this embodiment has a configuration of the built-in antenna for a radio communication terminal according to Embodiment 1 with dipole antenna 91 added to one side of base plate 11. Dipole antenna 91 has a configuration similar to that of dipole antenna 12.

[0064] Here, suppose one antenna making up the diversity antenna is dipole antenna 12 in Embodiment 1 and used for reception only. Suppose the other antenna making up the diversity antenna is dipole antenna 91 and used for both transmission and reception.

[0065] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 91 operates during transmission and dipole antenna 12 and dipole antenna 91 operate during reception to carry out diversity reception.

[0066] Thus, according to this embodiment, dipole antenna 12 in Embodiment 1 and dipole antenna 91 are used as the diversity antenna, and it is therefore possible to provide a high gain diversity antenna for a radio communication terminal with little influence from the human body. Moreover, adopting rectangular-wave-shaped dipole antenna 91 reduces the size of the diversity antenna.

(Embodiment 9)

[0067] Embodiment 9 is a mode in which the method of mounting dipole antenna 91 in Embodiment 8 is changed. Since Embodiment 9 is the same as Embodiment 8 except for the method of mounting dipole antenna 91, detailed explanations thereof will be omitted. Differences of the built-in antenna for a radio communication terminal according to this embodiment from Embodiment 8 will be explained below using FIG.15. The parts similar to those in Embodiment 8 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0068] FIG.15 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 9. As shown in this figure, dipole antenna 91 is mounted in such a way that the longitudinal direction thereof is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal. That is, this embodiment is different from Embodiment 8 in that dipole antenna 12 is mounted in such a way that the longitudinal direction of dipole antenna 12 is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal. As a result, dipole antenna 91 is provided in such a way that this longitudinal direction forms quasi right angles with respect to the human body and at the same time is quasi-parallel to the horizontal plane during a conversation.

[0069] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 91 operates during transmission and dipole antenna 12 and dipole antenna 91 operate during reception to carry out diversity reception. Thus, dipole antenna 12 can suppress deterioration of gain and at the same time mainly receive vertical polarized waves parallel to the longitudinal direction of the antenna element. Furthermore, dipole antenna 91 can not only suppress deterioration of gain but also mainly receive horizontal polarized waves parallel to the longitudinal direction of the antenna element. On the other hand, the signal sent from the other end of communication is often a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, even if there are either more vertical polarized waves or more horizontal polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the plane of polarization of the signal sent from the other end of communication and can thereby increase the reception gain.

[0070] Thus, this embodiment uses dipole antenna 12 in Embodiment 1 and dipole antenna 91 as the diversity antenna, and can thereby provide a high gain diversity antenna for a radio communication terminal with little influence from the human body. Moreover, the use of rectangular-wave-shaped dipole antenna 91 can reduce the size of the diversity antenna.

(Embodiment 10)

[0071] As shown in FIG.16, Embodiment 10 is a mode in which the dipole antenna used for both transmission and reception in Embodiment 8 is changed to dipole antenna 41 in Embodiment 3. Embodiment 10 is the same as Embodiment 8 except for the configuration and method of mounting the dipole antenna. The same parts in FIG.16 as those in Embodiment 8 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0072] FIG.16 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 10. As shown in this figure, dipole antenna 41 is mounted in such a way that the longitudinal direction of one antenna element is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal and the longitudinal direction of the other antenna element is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal.

[0073] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 41 operates during transmission and dipole antenna 12 and dipole antenna 41 operate during reception to carry out diversity reception.

[0074] Thus, dipole antenna 41 can suppress deterioration of gain and at the same time mainly receive vertical polarized waves and horizontal polarized waves parallel to the longitudinal direction of the antenna element. Furthermore, dipole antenna 12 can not only suppress deterioration of gain but also mainly receive vertical polarized waves parallel to the longitudinal direction of the antenna element. On the other hand, the signal sent from the other end of communication is often a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, even if there are either more vertical polarized waves or more horizontal polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the plane of polarization of the signal sent from the other end of communication and can thereby increase the reception gain.

[0075] Thus, this embodiment uses dipole antenna 12 in Embodiment 1 and dipole antenna 41 as the diversity antenna, and can thereby provide a high gain diversity antenna for a radio communication terminal with little influence from the human body. Moreover, the use of rectangular-wave-shaped dipole antenna 41 can reduce the size of the diversity antenna.

(Embodiment 11)

[0076] As shown in FIG.17, Embodiment 11 is a mode in which the dipole antenna used for reception in Embodiment 10 is changed to dipole antenna 121 with a configuration similar to dipole antenna 41 in Embodiment 3. Embodiment 11 is the same as Embodiment 8 except for the configuration and method of mounting the dipole antenna. The same parts in FIG.17 as those in Embodiment 8 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0077] FIG.17 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 11. As shown in this figure, dipole antenna 41 and dipole antenna 121 are mounted in such a way that the longitudinal direction of one antenna element is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal and the longitudinal direction of the other antenna element is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal.

[0078] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 41 operates during transmission and dipole antenna 41 and dipole antenna 121 operate during reception to carry out diversity reception.

[0079] Thus, dipole antenna 41 can suppress deterioration of gain and at the same time mainly receive vertical polarized waves and horizontal polarized waves parallel to the longitudinal direction of the antenna element. Furthermore, dipole antenna 121 can not only suppress deterioration of gain but also mainly receive vertical polarized waves parallel to the longitudinal direction of the antenna element. On the other hand, the signal sent from the other end of communication is often a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, even if there are either more vertical polarized waves or more horizontal polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the plane of polarization of the signal sent from the other end of communication and can thereby increase the reception gain.

[0080] Thus, this embodiment uses dipole antenna 121 in Embodiment 1 and dipole antenna 41 as the diversity antenna, and can thereby provide a high gain diversity antenna for a radio communication terminal with little influence from the human body. Moreover, the use of rectangular-wave-shaped dipole antenna 41 can reduce the size of the diversity antenna.

(Embodiment 12)

[0081] Embodiment 12 is a mode in which the configuration of the dipole antenna used in Embodiment 1 to Embodiment 11, Embodiment 17 to Embodiment 42, which will be described later and Embodiment 49 to Embodiment 59, which will be described later is changed.

[0082] FIG.18 is a schematic diagram showing a configuration of folded-dipole antenna 131 according to Embodiment 12. As shown in this figure, folded-dipole antenna 131 according to Embodiment 12 is formed in such a way that two rectangular-wave-shaped antenna elements are placed in parallel and the ends of these two antenna elements placed in parallel are shorted.

[0083] The folded-dipole antenna 131 in the above configuration is applicable as a built-in antenna for a radio communication terminal or as a dipole antenna making up a diversity antenna according to Embodiments 1 to 11, Embodiments 17 to 42, which will be described later and Embodiments 49 to 59, which will be described later.

[0084] Thus, applying folded-dipole antenna 131 as the dipole antenna to the configuration of each Embodiment above can attain effects similar to those in each Embodiment above and further increase impedance and perform impedance matching easily.

(Embodiment 13)

[0085] Embodiment 13 is a mode in which the configuration of the dipole antenna used in Embodiment 12 is changed. Embodiment 13 is the same as Embodiment 12 except for the configuration of the dipole antenna.

[0086] FIG.19 is a schematic diagram showing a configuration of folded-dipole antenna 141 used in Embodiment 13. As shown in this figure, folded-dipole antenna 141 according to Embodiment 13 is formed in such a way that two rectangular-wave-shaped antenna elements are placed in parallel and impedance elements 142 are attached to the ends of these two antenna elements placed in parallel.

[0087] The folded-dipole antenna 141 in the above configuration is applicable as a built-in antenna for a radio communication terminal or as a dipole antenna making up a diversity antenna according to Embodiments 1 to 11, Embodiments 17 to 42, which will be described later and Embodiments 49 to 59, which will be described later.

[0088] Thus, applying folded-dipole antenna 141 as the dipole antenna to the configuration of each Embodiment above can attain effects similar to those in each Embodiment above and further increase impedance and perform impedance matching easily. Furthermore, using folded-dipole antenna 141 in the above configuration as the dipole antenna can further widen the band and reduce the size of the antenna.

(Embodiment 14)

[0089] Embodiment 14 is a mode in which the configuration of the dipole antenna used in each embodiment above is changed. Embodiment 14 is the same as Embodiment 12 except for the configuration and method of mounting the dipole antenna.

[0090] FIG.20 is a schematic diagram showing a configuration of dipole antenna 151 used in Embodiment 14. As shown in this figure, dipole antenna 151 according to Embodiment 14 is constructed of a spiral antenna element.

[0091] The folded-dipole antenna 151 in the above configuration is applicable as a built-in antenna for a radio communication terminal or as a dipole antenna making up a diversity antenna according to Embodiments 1 to 11, Embodiments 17 to 42, which will be described later and Embodiments 49 to 59, which will be described later.

[0092] Thus, constructing a dipole antenna with a spiral antenna element can further reduce the size of the antenna.

(Embodiment 15)

[0093] Embodiment 15 is a mode in which the configuration of the dipole antenna used in each embodiment above is changed.

[0094] FIG.21 is a schematic diagram showing a configuration of folded-dipole antenna 161 used in Embodiment 15. As shown in this figure, folded-dipole antenna 161 according to Embodiment 15 is formed in such a way that the two spiral dipole antenna elements described in Embodiment 14 are placed in parallel and the ends of these two antenna elements are shorted.

[0095] The folded-dipole antenna 161 in the above configuration is applicable as a built-in antenna for a radio communication terminal or as a dipole antenna making up a diversity antenna according to Embodiments 1 to 11, Embodiments 17 to 42, which will be described later and Embodiments 49 to 59, which will be described later.

[0096] Thus, applying folded-dipole antenna 161 as the dipole antenna to the configuration of each embodiment above makes it possible to achieve effects similar to those in each embodiment above, improve impedance and perform impedance matching easily. Furthermore, adopting folded-dipole antenna 161 in the above configuration as the dipole antenna can further reduce the size of the antenna.

(Embodiment 16)

[0097] Embodiment 16 is a mode in which the configuration of the dipole antenna used in each Embodiment 15 is changed. Embodiment 16 is the same as Embodiment 15 except for the configuration and method of mounting the dipole antenna.

[0098] FIG.22 is a schematic diagram showing a configuration of folded-dipole antenna 171 used in Embodiment 16. As shown in this figure, folded-dipole antenna 171 according to Embodiment 16 is formed in such a way that the two spiral dipole antenna elements described in Embodiment 14 are placed in parallel and impedance elements 142 are attached to the ends of these two antenna elements.

[0099] The folded-dipole antenna 171 in the above configuration is applicable as a built-in antenna for a radio communication terminal or as a dipole antenna making up a diversity antenna according to Embodiments 1 to 11, Embodiments 17 to 42, which will be described later and Embodiments 49 to 59, which will be described later.

[0100] Thus, applying folded-dipole antenna 171 as the dipole antenna makes it possible to achieve effects similar to those in Embodiment 12, widen the band and reduce the size.

[0101] By the way, dipole antennas 131, 141, 161 and 171 above have a self-balancing action, and therefore a configuration without balanced/unbalanced conversion circuit 13 can also be used in Embodiment 12 to Embodiment 16.

(Embodiment 17)

[0102] Embodiment 17 is a mode in which dipole antenna 12 shown in Embodiment 1 is patterned on circuit board 181.

[0103] FIG.23 is a schematic diagram showing a configuration of dipole antenna 12 placed on circuit board 181 in Embodiment 17. As shown in this figure, dipole antenna 12 is patterned on circuit board 181.

[0104] Thus, using dipole antenna 12 shown in Embodiment 1, this embodiment can achieve effects similar to those in Embodiment 1. Furthermore, patterning dipole antenna 12 shown in Embodiment 1 on circuit board 181 makes it possible to obtain a stable characteristic.

[0105] By the way, this embodiment can also be implemented by patterning the dipole antenna shown in each embodiment above on circuit board 181.

(Embodiment 18)

[0106] Embodiment 18 is a mode in which dipole antenna 12 shown in each embodiment above is patterned on package case 191.

[0107] FIG.24 is a schematic diagram showing a configuration of dipole antenna 12 placed on package case 191 in Embodiment 18. As shown in this figure, dipole antenna 12 is patterned on circuit board 191.

[0108] Thus, using dipole antenna 12 shown in Embodiment 1, this embodiment can achieve effects similar to those in Embodiment 1. Furthermore, patterning dipole antenna 12 shown in Embodiment 1 on package case 191 makes it possible to obtain a stable characteristic, save the space for installing the antenna and thereby reduce the size of the apparatus.

[0109] By the way, this embodiment can also be implemented by patterning the dipole antenna shown in each embodiment above on circuit board 181.

(Embodiment 19)

[0110] Embodiment 19 is a mode in which the configuration of dipole antenna 12 in Embodiment 1 is changed. Embodiment 19 is the same as Embodiment 1 except for the configuration of dipole antenna 12 and therefore detailed explanations thereof will be omitted. Only differences of the built-in antenna for a radio communication terminal according to this embodiment from Embodiment 1 will be explained using FIG.25. The parts similar to those in Embodiment 1 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0111] FIG.25 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 19. As shown in this figure, the built-in antenna for a radio communication terminal according to Embodiment 19 is constructed of base plate 11, balanced/unbalanced conversion circuit 13, power supply terminals 14 and dipole antenna 201. One of the two antenna elements making up dipole antenna 201 is formed in a rectangular-wave shape and the other is formed in a bar shape. These two antenna elements are placed in such a way that their respective longitudinal directions form a straight line. The bar-shaped antenna element is placed outside a radio communication terminal, which is not shown.

[0112] Dipole antenna 201 is mounted in such a way that the longitudinal direction of the rectangular-wave-shaped antenna element is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal and the longitudinal direction of the bar-shaped antenna element is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal.

[0113] As shown above, dipole antenna 201 is mounted in such a way that the axial direction of the bar-shaped antenna element and the longitudinal direction of the rectangular-wave-shaped antenna element are quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal. This allows dipole antenna 201 to mainly receive vertical polarized waves parallel to the axial direction of the bar-shaped antenna element and the longitudinal direction of the rectangular-wave-shaped antenna element in a free space. During a conversation, the human body acts as a reflector, and therefore dipole antenna 201 has directivity opposite to the human body.

[0114] Then, the operation of the built-in antenna for a radio communication terminal in the above configuration will be explained. An unbalanced signal from the transmission/reception circuit above is converted to a balanced signal by balanced/unbalanced conversion circuit 13 and sent to dipole antenna 201. Dipole antenna 201 supplied with power in this way mainly sends vertical polarized waves parallel to this longitudinal direction. During reception, dipole antenna 201 receives vertical polarized waves parallel to the longitudinal direction above. Therefore, in a free space, vertical polarized waves are received from all directions centered on the dipole antenna and during a conversation, the human body acts as a reflector as described above, and therefore of the vertical polarized waves above, the vertical polarized waves from the direction opposite to the human body are mainly received.

[0115] In this way, dipole antenna 201 can not only suppress deterioration of gain but also mainly receive vertical polarized waves parallel to the longitudinal direction. On the other hand, the signal sent from the other end of communication is often a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, when there are more vertical polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the plane of polarization of the signal sent from the other end of communication and can thereby increase the reception gain.

[0116] The signal above (balanced signal) received from dipole antenna 201 is sent to the transmission/reception circuit via balanced/unbalanced conversion circuit 13. Here, the current that flows into base plate 11 is suppressed to a minimum by the above-described balanced/unbalanced conversion circuit 13, and therefore the antenna operation by base plate 11 is prevented. This minimizes the reduction of gain caused by influences from the human body.

[0117] Thus, according to this embodiment, balanced/unbalanced conversion circuit 13 can minimize the antenna current that flows into base plate 11, and can thereby suppress deterioration of gain of dipole antenna 201 caused by influences from the human body. Furthermore, adopting a square-wave shape for one of the antenna elements of dipole antenna 201 makes it possible to reduce the size of the built-in antenna for a radio communication terminal. Therefore, it is possible to provide a high gain and small built-in antenna for a radio communication terminal with little influence from the human body.

(Embodiment 20)

[0118] Embodiment 20 is a mode in which the configuration and method of mounting dipole antenna 201 in Embodiment 19 are changed. Embodiment 20 is the same as Embodiment 19 except for the configuration and method of mounting dipole antenna 201, and therefore detailed explanations thereof will be omitted. Only differences of the built-in antenna for a radio communication terminal according to this embodiment from Embodiment 19 will be explained using FIG.26. The parts similar to those in Embodiment 19 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0119] FIG.26 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 20. As shown in this figure, the built-in antenna for a radio communication terminal according to Embodiment 20 is constructed of base plate 11, balanced/unbalanced conversion circuit 13, power supply terminals 14 and dipole antenna 211. The two antenna elements making up dipole antenna 211 are placed in such a way that the longitudinal direction of the rectangular-wave-shaped antenna element and the longitudinal direction of the bar-shaped antenna element intersect at quasi-right angles.

[0120] Dipole antenna 211 is mounted in such a way that the longitudinal direction of the rectangular-wave-shaped antenna element is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal and the longitudinal direction of the bar-shaped antenna element is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal. That is, this embodiment differs from Embodiment 19 in that dipole antenna 12 is mounted in such a way that the longitudinal direction thereof is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal.

[0121] Then, the operation of the built-in antenna for a radio communication terminal in the above configuration will be explained. An unbalanced signal from the transmission/reception circuit above is converted to a balanced signal by balanced/unbalanced conversion circuit 13 and sent to dipole antenna 211. The bar-shaped antennal element placed quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal making up dipole antenna 211 supplied with power in this way mainly sends vertical polarized waves. During reception, dipole antenna 211 receives vertical polarized waves parallel to the longitudinal direction above. On the other hand, the rectangular-wave-shaped antenna element placed quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal making up dipole antenna 12 supplied with power in this way mainly sends horizontal polarized waves parallel to this longitudinal direction. During reception, dipole antenna 211 receives horizontal polarized waves parallel to the longitudinal direction above. Therefore, in a free space, vertical polarized waves and horizontal polarized waves are received from all directions centered on the dipole antenna and during a conversation, the human body acts as a reflector, and therefore of the vertical polarized waves and horizontal polarized waves above, the waves from the direction opposite to the human body are mainly received.

[0122] Thus, dipole antenna 211 can not only suppress deterioration of gain but also mainly receive both vertical polarized waves and horizontal polarized waves. On the other hand, the signal sent from the other end of communication is often a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. That is, even if there are either more vertical polarized waves or more horizontal polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the plane of polarization of the signal sent from the other end of communication and can thereby increase the reception gain.

[0123] Thus, this embodiment can achieve effects similar to those of Embodiment 20.

(Embodiment 21)

[0124] Embodiment 21 is a mode in which the configuration and method of mounting dipole antenna 201 in Embodiment 19 are changed. Embodiment 21 is the same as Embodiment 19 except for the configuration and method of mounting dipole antenna 201 and therefore detailed explanations thereof will be omitted. Only differences of the built-in antenna for a radio communication terminal according to this embodiment from Embodiment 19 will be explained using FIG.27. The parts similar to those in Embodiment 19 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0125] FIG.27 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 21. As shown in this figure, the built-in antenna for a radio communication terminal according to Embodiment 21 is constructed of base plate 11, balanced/unbalanced conversion circuit 13, power supply terminals 14 and dipole antenna 221. The two antenna elements making up dipole antenna 221 are folded near the center and the part of the folded antenna element including power supply terminals 14 is rectangular-wave-shaped and the part of the folded antenna element without power supply terminals 14 is bar-shaped. Dipole antenna 221 is placed in such a way that the longitudinal directions of the rectangular-wave-shaped parts of the antenna elements form a quasi-straight line. The bar-shaped parts of the antenna elements are placed outside the package of the radio communication terminal, which is not shown.

[0126] Dipole antenna 221 in the above configuration is mounted in such a way that the longitudinal directions of the folded rectangular-wave-shaped parts of the antenna elements making up dipole antenna 221 are quasi-parallel to the upper surface (horizontal surface) of the radio communication terminal. In this case, the bar-shaped parts of the antenna elements are placed quasi-perpendicular to the upper surface (horizontal surface) of the radio communication terminal.

[0127] Dipole antenna 221 is mounted in such a way that the longitudinal direction of the rectangular-wave-shaped part of the antenna element is quasi-parallel to the upper surface (horizontal surface) of the radio communication terminal. Mounting dipole antenna 221 in this way makes the axial direction of the bar-shaped part of the antenna element quasi-perpendicular to the upper surface (horizontal surface) of the radio communication terminal.

[0128] Then, the operation of the built-in antenna for a radio communication terminal in the above configuration will be explained. An unbalanced signal from the transmission/reception circuit above is converted to a balanced signal by balanced/unbalanced conversion circuit 13 and then sent to dipole antenna 221. The bar-shaped part of the antenna element placed quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal that makes up dipole antenna 221 supplied with power in this way mainly sends vertical polarized waves parallel to the axial direction of this antenna element. Furthermore, during reception, vertical polarized waves parallel to the axial direction above are received. On the other hand, the rectangular-wave-shaped part of the antenna element placed quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal that makes up dipole antenna 12 supplied with power in the same way mainly sends horizontal polarized waves parallel to this longitudinal direction. Furthermore, during reception, horizontal polarized waves parallel to the longitudinal direction above are received. Thus, in a free space, vertical polarized waves and horizontal polarized waves from all directions centered on the dipole antenna are received, and during a conversation, since the human body acts as a reflector as described above, of the vertical polarized waves, the vertical polarized waves and horizontal polarized waves opposite to the human body are mainly received.

[0129] This allows dipole antenna 221 to suppress deterioration of gain and mainly receive horizontal polarized waves parallel to the longitudinal direction of the rectangular-wave-shaped part and vertical polarized waves parallel to the axial direction of the bar-shaped part. On the other hand, a signal sent from the other end of communication is a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, even if there are either more vertical polarized waves or more horizontal polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the polarization plane of the signal sent from the other end of communication, making it possible to increase reception gain.

[0130] Thus, this embodiment can also achieve effects similar to those of Embodiment 20.

(Embodiment 22)

[0131] Embodiment 22 is a mode in which the configuration of the bar-shaped antenna element that makes up dipole antenna 201 in Embodiment 19 is changed. The antenna for a radio communication terminal according to this embodiment will be explained below using FIG.28. The parts similar to those in Embodiment 19 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0132] FIG.28 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 22. As shown in FIG.28, the antenna for a radio communication terminal according to Embodiment 22 is constructed of base plate 11, balanced/unbalanced conversion circuit 13 and dipole antenna 231. Dipole antenna 231 adopts a configuration in which the bar-shaped antenna element making up dipole antenna 201 is formed in a rectangular-wave shape.

[0133] Then, the operation of the built-in antenna for a radio communication terminal in the above configuration will be explained. An unbalanced signal from the transmission/reception circuit above is converted to a balanced signal by balanced/unbalanced conversion circuit 13 and then sent to dipole antenna 231. Dipole antenna 231 supplied with power in this way is placed in such a way that the longitudinal direction is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal, and therefore mainly sends vertical polarized waves parallel to this longitudinal direction. Furthermore, during reception, vertical polarized waves parallel to the longitudinal direction above are received. Thus, in a free space, vertical polarized waves from all directions centered on the dipole antenna are received, and during a conversation, since the human body acts as a reflector as described above, of the vertical polarized waves above, the vertical polarized waves opposite to the human body are mainly received.

[0134] This allows dipole antenna 231 to suppress deterioration of gain and mainly receive vertical polarized waves parallel to the longitudinal direction of the antenna element. On the other hand, a signal sent from the other end of communication is a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, when there are more vertical polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the polarization plane of the signal sent from the other end of communication, allowing reception gain to be increased.

[0135] Thus, this embodiment can achieve effects similar to those of Embodiment 19 and at the same time reduce the size of the external antenna.

(Embodiment 23)

[0136] Embodiment 23 is a mode in which the configuration of the bar-shaped antenna element that makes up dipole antenna 211 in Embodiment 20 is changed. The antenna for a radio communication terminal according to this embodiment will be explained below using FIG.29. The parts similar to those in Embodiment 20 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0137] FIG.29 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 23. As shown in FIG.29, the antenna for a radio communication terminal according to Embodiment 23 is constructed of base plate 11, balanced/unbalanced conversion circuit 13 and dipole antenna 241. Dipole antenna 241 adopts a configuration in which the bar-shaped antenna element making up dipole antenna 211 is changed to a rectangular-wave shape.

[0138] Then, the operation of the built-in antenna for a radio communication terminal in the above configuration will be explained. An unbalanced signal from the transmission/reception circuit above is converted to a balanced signal by balanced/unbalanced conversion circuit 13 and then sent to dipole antenna 241. Dipole antenna 241 supplied with power in this way is placed in such a way that the longitudinal direction of one antenna element is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal and the longitudinal direction of the other antenna element is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal, and therefore sends vertical and horizontal polarized waves parallel to these longitudinal directions. Furthermore, during reception, vertical polarized waves and horizontal polarized waves parallel to the longitudinal directions above are received. Thus, in a free space, vertical polarized waves and horizontal polarized waves from all directions centered on the dipole antenna are received, and during a conversation, since the human body acts as a reflector as described above, of the vertical and horizontal polarized waves above, the vertical polarized waves opposite to the human body are mainly received.

[0139] This allows dipole antenna 241 to suppress deterioration of gain and mainly receive vertical polarized waves and horizontal polarized waves parallel to the longitudinal directions. Dipole antenna 241 can suppress deterioration of gain and mainly receive horizontal polarized waves parallel to the longitudinal direction. On the other hand, a signal sent from the other end of communication is a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, when there are either more vertical polarized waves or more horizontal polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the polarization plane of the signal sent from the other end of communication, allowing reception gain to be increased.

[0140] Thus, this embodiment can achieve effects similar to those of Embodiment 20 and at the same time reduce the size of the external antenna.

(Embodiment 24)

[0141] Embodiment 24 is a mode in which the configuration of the bar-shaped part of the antenna element that makes up dipole antenna 221 in Embodiment 21 is changed. The antenna for a radio communication terminal according to this embodiment will be explained below using FIG.30. The same configurations as those in Embodiment 21 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0142] FIG.30 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 24. As shown in FIG.30, the antenna for a radio communication terminal according to Embodiment 24 is constructed of base plate 11, balanced/unbalanced conversion circuit 13, power supply terminals 14 and dipole antenna 251. Dipole antenna 251 adopts a configuration in which the bar-shaped antenna element making up dipole antenna 221 is changed to a rectangular-wave shape.

[0143] Then, the operation of the built-in antenna for a radio communication terminal in the above configuration will be explained. An unbalanced signal from the transmission/reception circuit above is converted to a balanced signal by balanced/unbalanced conversion circuit 13 and then sent to dipole antenna 251. Of the antenna elements that make up dipole antenna 251 supplied with power in this way, the part placed quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal mainly sends vertical polarized waves parallel to this longitudinal direction of this part. Furthermore, during reception, vertical polarized waves parallel to the longitudinal direction above are received. On the other hand, the part placed quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal of the antenna elements that make up dipole antenna 251 supplied with power in the same way mainly sends horizontal polarized waves parallel to this longitudinal direction of this part. Furthermore, during reception, horizontal polarized waves parallel to the longitudinal direction above are received. Thus, in a free space, vertical polarized waves and horizontal polarized waves from all directions centered on the dipole antenna are received, and during a conversation, since the human body acts as a reflector as described above, of the vertical and horizontal polarized waves above, the waves opposite to the human body are mainly received.

[0144] This allows dipole antenna 251 to suppress deterioration of gain and mainly receive vertical polarized waves and horizontal polarized waves parallel to the longitudinal directions of the respective antenna elements. On the other hand, a signal sent from the other end of communication is a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, when there are either more vertical polarized waves or more horizontal polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the polarization plane of the signal sent from the other end of communication, making it possible to increase reception gain.

[0145] Thus, this embodiment can achieve effects similar to those of Embodiment 21 and at the same time reduce the size of the external antenna.

(Embodiment 25)

[0146] Embodiment 25 to Embodiment 38 are modes in which a diversity antenna is implemented using the built-in antenna for a radio communication terminal in Embodiment 19 to Embodiment 24.

[0147] Embodiment 25 is a mode in which a diversity antenna is implemented using the built-in antenna for a radio communication terminal in Embodiment 19. The diversity antenna for a radio communication terminal according to this embodiment will be explained below using FIG.31. The configurations similar to those in Embodiment 19 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0148] FIG.31 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 25. As shown in FIG.31, the diversity antenna according to this embodiment is constructed of the configuration of the built-in antenna for a radio communication terminal according to this Embodiment 19 with additional dipole antenna 261. Dipole antenna 261 has a configuration similar to that of dipole antenna 201.

[0149] Here, suppose one antenna making up the diversity antenna is dipole antenna 201 in Embodiment 19 and used for reception only. Also suppose the other antenna making up the diversity antenna is dipole antenna 261 and used for both transmission and reception.

[0150] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 261 operates during transmission and dipole antenna 201 and dipole antenna 261 operate during reception to carry out diversity reception.

[0151] Thus, according to this embodiment, dipole antenna 201 in Embodiment 19 and dipole antenna 261 are used as the diversity antenna, which makes it possible to provide a high gain and small diversity antenna for a radio communication terminal with little influence from the human body as in the case of Embodiment 19.

(Embodiment 26)

[0152] Embodiment 26 is a mode in which a diversity antenna is implemented using the built-in antenna for a radio communication terminal in Embodiment 20. The diversity antenna for a radio communication terminal according to this embodiment will be explained below using FIG.32. The configurations similar to those in Embodiment 20 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0153] FIG.32 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 26. As shown in FIG.32, the diversity antenna according to this embodiment is constructed of the configuration of the built-in antenna for a radio communication terminal according to this Embodiment 20 with additional dipole antenna 271. Dipole antenna 271 has a configuration similar to that of dipole antenna 211.

[0154] Here, suppose one antenna making up the diversity antenna is dipole antenna 211 in Embodiment 20 and used for reception only. Also suppose the other antenna making up the diversity antenna is dipole antenna 271 and used for both transmission and reception.

[0155] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 271 operates during transmission and dipole antenna 211 and dipole antenna 271 operate during reception to carry out diversity reception.

[0156] Thus, according to this embodiment, dipole antenna 211 in Embodiment 20 and dipole antenna 271 are used as the diversity antenna, which makes it possible to provide a high gain and small diversity antenna for a radio communication terminal with little influence from the human body as in the case of Embodiment 20.

(Embodiment 27)

[0157] Embodiment 27 is a mode in which a diversity antenna is implemented using the built-in antenna for a radio communication terminal in Embodiment 22. The diversity antenna for a radio communication terminal according to this embodiment will be explained below using FIG.33. The configurations similar to those in Embodiment 22 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0158] FIG.33 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 27. As shown in FIG.33, the diversity antenna according to this embodiment is constructed of the configuration of the built-in antenna for a radio communication terminal according to this Embodiment 22 with additional dipole antenna 281. Dipole antenna 281 has a configuration similar to that of dipole antenna 231.

[0159] Here, suppose one antenna making up the diversity antenna is dipole antenna 231 in Embodiment 22 and used for reception only. Also suppose the other antenna making up the diversity antenna is dipole antenna 281 and used for both transmission and reception.

[0160] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 281 operates during transmission and dipole antenna 231 and dipole antenna 281 operate during reception to carry out diversity reception.

[0161] Thus, according to this embodiment, dipole antenna 231 in Embodiment 22 and dipole antenna 281 are used as the diversity antenna, which makes it possible to provide a high gain and small diversity antenna for a radio communication terminal with little influence from the human body as in the case of Embodiment 22.

(Embodiment 28)

[0162] Embodiment 28 is a mode in which a diversity antenna is implemented using the built-in antenna for a radio communication terminal in Embodiment 23. The diversity antenna for a radio communication terminal according to this embodiment will be explained below using FIG.34. The configurations similar to those in Embodiment 23 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0163] FIG.34 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 28. As shown in FIG.34, the diversity antenna according to this embodiment is constructed of the configuration of the built-in antenna for a radio communication terminal according to this Embodiment 23 with additional dipole antenna 291. Dipole antenna 291 has a configuration similar to that of dipole antenna 241.

[0164] Here, suppose one antenna making up the diversity antenna is dipole antenna 241 in Embodiment 23 and used for reception only. Also suppose the other antenna making up the diversity antenna is dipole antenna 291 and used for both transmission and reception.

[0165] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 291 operates during transmission and dipole antenna 241 and dipole antenna 291 operate during reception to carry out diversity reception.

[0166] Thus, according to this embodiment, dipole antenna 241 in Embodiment 23 and dipole antenna 291 are used as the diversity antenna, which makes it possible to provide a high gain and small diversity antenna for a radio communication terminal with little influence from the human body as in the case of Embodiment 23.

(Embodiment 29)

[0167] Embodiment 29 is a mode in which a diversity antenna is implemented using the built-in antenna for a radio communication terminal in Embodiment 19. The diversity antenna for a radio communication terminal according to this embodiment will be explained below using FIG.35. The configurations similar to those in Embodiment 1 and Embodiment 19 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0168] FIG.35 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 29. As shown in FIG.35, the diversity antenna according to this embodiment is constructed of the configuration of the built-in antenna for a radio communication terminal according to this Embodiment 19 with additional dipole antenna 12 shown in Embodiment 1.

[0169] Here, suppose one antenna making up the diversity antenna is dipole antenna 12 in Embodiment 1 and used for reception only. Also suppose the other antenna making up the diversity antenna is dipole antenna 201 in Embodiment 19 and used for both transmission and reception.

[0170] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 201 operates during transmission and dipole antenna 201 and dipole antenna 12 operate during reception to carry out diversity reception.

[0171] Thus, according to this embodiment, dipole antenna 12 in Embodiment 1 and dipole antenna 201 in Embodiment 19 are used as the diversity antenna, which makes it possible to provide a high gain and small diversity antenna for a radio communication terminal with little influence from the human body as in the case of Embodiment 19.

(Embodiment 30)

[0172] Embodiment 30 is a mode in which a diversity antenna is implemented using the built-in antennas for a radio communication terminal in Embodiment 2 and Embodiment 19. The diversity antenna for a radio communication terminal according to this embodiment will be explained below using FIG.36. The configurations similar to those in Embodiment 2 and Embodiment 19 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0173] FIG.36 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 30. As shown in FIG.36, the diversity antenna according to this embodiment is constructed of the configuration of the built-in antenna for a radio communication terminal according to Embodiment 19 with additional dipole antenna 12 shown in Embodiment 2.

[0174] Here, suppose one antenna making up the diversity antenna is dipole antenna 12 in Embodiment 2 and used for reception only. Also suppose the other antenna making up the diversity antenna is dipole antenna 201 in Embodiment 19 and used for both transmission and reception.

[0175] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 201 operates during transmission and dipole antenna 201 and dipole antenna 12 operate during reception to carry out diversity reception.

[0176] Thus, according to this embodiment, dipole antenna 12 in Embodiment 2 and dipole antenna 201 in Embodiment 19 are used as the diversity antenna, which makes it possible to provide a high gain and small diversity antenna for a radio communication terminal with little influence from the human body as in the case of Embodiment 1 and Embodiment 19.

(Embodiment 31)

[0177] Embodiment 31 is a mode in which a diversity antenna is implemented using the built-in antennas for a radio communication terminal in Embodiment 3 and Embodiment 19. The diversity antenna for a radio communication terminal according to this embodiment will be explained below using FIG.37. The configurations similar to those in Embodiment 3 and Embodiment 19 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0178] FIG.37 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 31. As shown in FIG.37, the diversity antenna according to this embodiment is constructed of the configuration of the built-in antenna for a radio communication terminal according to Embodiment 19 with additional dipole antenna 41 shown in Embodiment 3.

[0179] Here, suppose one antenna making up the diversity antenna is dipole antenna 41 in Embodiment 3 and used for reception only. Also suppose the other antenna making up the diversity antenna is dipole antenna 201 in Embodiment 19 and used for both transmission and reception.

[0180] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 201 operates during transmission and dipole antenna 201 and dipole antenna 41 operate during reception to carry out diversity reception.

[0181] Thus, according to this embodiment, dipole antenna 41 in Embodiment 3 and dipole antenna 201 in Embodiment 19 are used as the diversity antenna, which makes it possible to provide a high gain and small diversity antenna for a radio communication terminal with little influence from the human body as in the case of Embodiment 3 and Embodiment 19.

(Embodiment 32)

[0182] Embodiment 32 is a mode in which a diversity antenna is implemented using the built-in antennas for a radio communication terminal in Embodiment 1 and Embodiment 20. The diversity antenna for a radio communication terminal according to this embodiment will be explained below using FIG.38. The configurations similar to those in Embodiment 1 and Embodiment 20 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0183] FIG.38 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 32. As shown in FIG.38, the diversity antenna according to this embodiment is constructed of the configuration of the built-in antenna for a radio communication terminal according to Embodiment 20 with additional dipole antenna 12 shown in Embodiment 1.

[0184] Here, suppose one antenna making up the diversity antenna is dipole antenna 12 in Embodiment 1 and used for reception only. Also suppose the other antenna making up the diversity antenna is dipole antenna 211 in Embodiment 20 and used for both transmission and reception.

[0185] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 211 operates during transmission and dipole antenna 211 and dipole antenna 12 operate during reception to carry out diversity reception.

[0186] Thus, according to this embodiment, dipole antenna 12 in Embodiment 1 and dipole antenna 211 in Embodiment 20 are used as the diversity antenna, which makes it possible to provide a high gain and small diversity antenna for a radio communication terminal with little influence from the human body as in the case of Embodiment 1 and Embodiment 20.

(Embodiment 33)

[0187] Embodiment 33 is a mode in which a diversity antenna is implemented using the built-in antennas for a radio communication terminal in Embodiment 3 and Embodiment 20. The diversity antenna for a radio communication terminal according to this embodiment will be explained below using FIG.39. The configurations similar to those in Embodiment 3 and Embodiment 20 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0188] FIG.39 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 33. As shown in FIG.39, the diversity antenna according to this embodiment is constructed of the configuration of the built-in antenna for a radio communication terminal according to Embodiment 20 with additional dipole antenna 41 shown in Embodiment 3.

[0189] Here, suppose one antenna making up the diversity antenna is dipole antenna 41 in Embodiment 3 and used for reception only. Also suppose the other antenna making up the diversity antenna is dipole antenna 211 in Embodiment 20 and used for both transmission and reception.

[0190] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 211 operates during transmission and dipole antenna 211 and dipole antenna 41 operate during reception to carry out diversity reception.

[0191] Thus, according to this embodiment, dipole antenna 41 in Embodiment 3 and dipole antenna 211 in Embodiment 20 are used as the diversity antenna, which makes it possible to provide a high gain and small diversity antenna for a radio communication terminal with little influence from the human body as in the case of Embodiment 3 and Embodiment 20.

(Embodiment 34)

[0192] Embodiment 34 is a mode in which a diversity antenna is implemented using the built-in antennas for a radio communication terminal in Embodiment 1 and Embodiment 22. The diversity antenna for a radio communication terminal according to this embodiment will be explained below using FIG.40. The configurations similar to those in Embodiment 1 and Embodiment 22 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0193] FIG.40 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 34. As shown in FIG.40, the diversity antenna according to this embodiment is constructed of the configuration of the built-in antennas for a radio communication terminal according to Embodiment 22 with additional dipole antenna 12 shown in Embodiment 1.

[0194] Here, suppose one antenna making up the diversity antenna is dipole antenna 12 in Embodiment 1 and used for reception only. Also suppose the other antenna making up the diversity antenna is dipole antenna 231 in Embodiment 22 and used for both transmission and reception.

[0195] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 231 operates during transmission and dipole antenna 231 and dipole antenna 12 operate during reception to carry out diversity reception.

[0196] Thus, according to this embodiment, dipole antenna 12 in Embodiment 1 and dipole antenna 231 in Embodiment 22 are used as the diversity antenna, which makes it possible to provide a high gain and small diversity antenna for a radio communication terminal with little influence from the human body as in the case of Embodiment 1 and Embodiment 22.

(Embodiment 35)

[0197] Embodiment 35 is a mode in which a diversity antenna is implemented using the built-in antennas for a radio communication terminal in Embodiment 2 and Embodiment 22. The diversity antenna for a radio communication terminal according to this embodiment will be explained below using FIG.41. The configurations similar to those in Embodiment 2 and Embodiment 22 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0198] FIG.41 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 35. As shown in FIG.41, the diversity antenna according to this embodiment is constructed of the configuration of the built-in antenna for a radio communication terminal according to Embodiment 22 with additional dipole antenna 12 shown in Embodiment 2.

[0199] Here, suppose one antenna making up the diversity antenna is dipole antenna 12 in Embodiment 2 and used for reception only. Also suppose the other antenna making up the diversity antenna is dipole antenna 231 in Embodiment 22 and used for both transmission and reception.

[0200] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 231 operates during transmission and dipole antenna 231 and dipole antenna 12 operate during reception to carry out diversity reception.

[0201] Thus, according to this embodiment, dipole antenna 12 in Embodiment 2 and dipole antenna 231 in Embodiment 22 are used as the diversity antenna, which makes it possible to provide a high gain and small diversity antenna for a radio communication terminal with little influence from the human body as in the case of Embodiment 2 and Embodiment 22.

(Embodiment 36)

[0202] Embodiment 36 is a mode in which a diversity antenna is implemented using the built-in antennas for a radio communication terminal in Embodiment 3 and Embodiment 22. The diversity antenna for a radio communication terminal according to this embodiment will be explained below using FIG.42. The configurations similar to those in Embodiment 3 and Embodiment 22 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0203] FIG.42 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 36. As shown in FIG.42, the diversity antenna according to this embodiment is constructed of the configuration of the built-in antenna for a radio communication terminal according to Embodiment 22 with additional dipole antenna 41 shown in Embodiment 3.

[0204] Here, suppose one antenna making up the diversity antenna is dipole antenna 41 in Embodiment 3 and used for reception only. Also suppose the other antenna making up the diversity antenna is dipole antenna 231 in Embodiment 22 and used for both transmission and reception.

[0205] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 231 operates during transmission and dipole antenna 231 and dipole antenna 41 operate during reception to carry out diversity reception.

[0206] Thus, according to this embodiment, dipole antenna 41 in Embodiment 3 and dipole antenna 231 in Embodiment 22 are used as the diversity antenna, which makes it possible to provide a high gain and small diversity antenna for a radio communication terminal with little influence from the human body as in the case of Embodiment 3 and Embodiment 22.

(Embodiment 37)

[0207] Embodiment 37 is a mode in which a diversity antenna is implemented using the built-in antennas for a radio communication terminal in Embodiment 1 and Embodiment 23. The diversity antenna for a radio communication terminal according to this embodiment will be explained below using FIG.43. The configurations similar to those in Embodiment 1 and Embodiment 23 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0208] FIG.43 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 37. As shown in FIG.43, the diversity antenna according to this embodiment is constructed of the configuration of the built-in antenna for a radio communication terminal according to Embodiment 23 with additional dipole antenna 12 shown in Embodiment 1.

[0209] Here, suppose one antenna making up the diversity antenna is dipole antenna 12 in Embodiment 1 and used for reception only. Also suppose the other antenna making up the diversity antenna is dipole antenna 241 in Embodiment 23 and used for both transmission and reception.

[0210] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 241 operates during transmission and dipole antenna 241 and dipole antenna 12 operate during reception to carry out diversity reception.

[0211] Thus, according to this embodiment, dipole antenna 12 in Embodiment 1 and dipole antenna 241 in Embodiment 23 are used as the diversity antenna, which makes it possible to provide a high gain and small diversity antenna for a radio communication terminal with little influence from the human body as in the case of Embodiment 1 and Embodiment 23.

(Embodiment 38)

[0212] Embodiment 38 is a mode in which a diversity antenna is implemented using the built-in antennas for a radio communication terminal in Embodiment 3 and Embodiment 23. The diversity antenna for a radio communication terminal according to this embodiment will be explained below using FIG.44. The configurations similar to those in Embodiment 3 and Embodiment 23 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0213] FIG.44 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 38. As shown in FIG.44, the diversity antenna according to this embodiment is constructed of the configuration of the built-in antenna for a radio communication terminal according to Embodiment 23 with additional dipole antenna 41 shown in Embodiment 3.

[0214] Here, suppose one antenna making up the diversity antenna is dipole antenna 41 in Embodiment 3 and used forreceptiononly. Also suppose the other antenna making up the diversity antenna is dipole antenna 241 in Embodiment 23 and used for both transmission and reception.

[0215] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 241 operates during transmission and dipole antenna 241 and dipole antenna 41 operate during reception to carry out diversity reception.

[0216] Thus, according to this embodiment, dipole antenna 41 in Embodiment 3 and dipole antenna 241 in Embodiment 23 are used as the diversity antenna, which makes it possible to provide a high gain and small diversity antenna for a radio communication terminal with little influence from the human body as in the case of Embodiment 3 and Embodiment 23.

(Embodiment 39)

[0217] Embodiment 39 is a mode in which the configuration of dipole antenna 41 in Embodiment 3 is changed. Embodiment 39 is the same as Embodiment 3 except for the configuration of the dipole antenna, and therefore detailed explanations thereof will be omitted.
Differences of the built-in antenna for a radio communication terminal according to this embodiment from Embodiment 3 will be explained below using FIG.45. The parts similar to those in Embodiment 3 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0218] FIG.45 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 39. As shown in this figure, the built-in antenna for a radio communication terminal according to Embodiment 39 is constructed of base plate 11, balanced/unbalanced conversion circuit 13 and dipole antenna 401. One of the two antenna elements making up dipole antenna 401 is formed in a rectangular-wave shape and the other is formed in a bar shape. These two antenna elements are placed in such a way that the longitudinal direction of the rectangular-wave-shaped antenna element intersects the axial direction of the bar-shaped antenna element at quasi-right angles.

[0219] Dipole antenna 401 is mounted in such a way that the longitudinal direction of the rectangular-wave-shaped antenna element is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal. On the other hand, the axial direction of the bar-shaped antenna element is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal.

[0220] As shown above, dipole antenna 401 is mounted in such a way that the longitudinal direction of the rectangular-wave-shaped antenna element is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal. On the other hand, the axial direction of the bar-shaped antenna element is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal. This allows dipole antenna 401 to receive vertical polarized waves parallel to the longitudinal direction and horizontal polarized waves parallel to the longitudinal direction in a free space. Furthermore, during a conversation, the human body acts as a reflector, and therefore dipole antenna 401 has directivity opposite to the human body.

[0221] Then, the operation of the built-in antenna for a radio communication terminal in the above configuration will be explained. An unbalanced signal from the transmission/reception circuit above is converted to a balanced signal by balanced/unbalanced conversion circuit 13 and sent to dipole antenna 401. The rectangular-wave-shaped antenna element of dipole antenna 401 supplied with power in this way mainly sends vertical polarized waves parallel to this longitudinal direction. Furthermore, during reception, it receives vertical polarized waves parallel to the longitudinal direction above. On the other hand, the bar-shaped antenna element of dipole antenna 401 supplied with power in this way mainly sends horizontal polarized waves.
Furthermore, during reception, it receives horizontal polarized waves parallel to the axial direction of the bar-shaped antenna element. Therefore, in a free space, vertical polarized waves and horizontal polarized waves are received from all directions centered on the dipole antenna, and during a conversation, the human body acts as a reflector, and therefore of the vertical polarized waves above, the vertical polarized waves and horizontal polarized waves from the direction opposite to the human body are mainly received.

[0222] The signal above (balanced signal) received from dipole antenna 401 is sent to the transmission/reception circuit above via balanced/unbalanced conversion circuit 13. Here, the current that flows into base plate 11 is suppressed to a minimum by above-described balanced/unbalanced conversion circuit 13, and therefore the antenna operation by base plate 11 is prevented. This minimizes the reduction of gain caused by influences from the human body.

[0223] Thus, according to this embodiment, balanced/unbalanced conversion circuit 13 can minimize the antenna current that flows into base plate 11, and can thereby suppress deterioration of gain of dipole antenna 201 caused by influences from the human body. Furthermore, adopting a rectangular-wave shape for one of the antenna elements of dipole antenna 401 makes it possible to reduce the size of the built-in antenna for a radio communication terminal. Therefore, it is possible to provide a high gain and small built-in antenna for a radio communication terminal with little influence from the human body.

[0224] Furthermore, by mainly receiving vertical polarized waves using the rectangular-wave-shaped antenna element and mainly receiving horizontal polarized waves using the bar-shaped antenna element, it is possible to change the ratio of polarization of vertical polarized waves to horizontal polarized waves as appropriate and thereby receive at a ratio of polarization according to the purpose of use of the antenna.

(Embodiment 40)

[0225] Embodiment 40 is a mode in which the configuration of dipole antenna 401 in Embodiment 39 is changed. Embodiment 40 is the same as Embodiment 39 except for the configuration of dipole antenna 401, and therefore detailed explanations thereof will be omitted.
Differences of the built-in antenna for a radio communication terminal according to this embodiment from Embodiment 39 will be explained below using FIG.46. The parts similar to those in Embodiment 39 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0226] FIG.46 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 40. As shown in this figure, the built-in antenna for a radio communication terminal according to Embodiment 40 is constructed of base plate 11, balanced/unbalanced conversion circuit 13 and dipole antenna 411. The two antenna elements making up dipole antenna 411 are placed in such a way that the longitudinal direction of the rectangular-wave-shaped antenna element intersects the axial direction of the bar-shaped antenna element at quasi-right angles.

[0227] Dipole antenna 411 is mounted in such a way that the longitudinal direction of the rectangular-wave-shaped antenna element is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal. On the other hand, the axial direction of the bar-shaped antenna element is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal.

[0228] This allows dipole antenna 411 to receive horizontal polarized waves parallel to the longitudinal direction of the rectangular-wave-shaped antenna element and vertical polarized waves parallel to the axial direction of the bar-shaped antenna element in a free space. Furthermore, during a conversation, the human body acts as a reflector, and therefore dipole antenna 401 has directivity opposite to the human body.

[0229] Thus, this embodiment can also achieve effects similar to those of Embodiment 39. Furthermore, by mainly receiving vertical polarized waves using the bar-shaped antenna element and mainly receiving horizontal polarized waves using the rectangular-wave-shaped antenna element, it is possible to change the ratio of polarization of vertical polarized waves to horizontal polarized waves as appropriate and thereby receive at a ratio of polarization according to the purpose of use of the antenna.

(Embodiment 41)

[0230] Embodiment 41 is a mode in which the configuration of dipole antenna 51 in Embodiment 4 is changed. Embodiment 41 is the same as Embodiment 4 except for the configuration of the dipole antenna, and therefore detailed explanations thereof will be omitted.
Differences of the built-in antenna for a radio communication terminal according to this embodiment from Embodiment 4 will be explained below using FIG.47. The parts similar to those in Embodiment 4 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0231] FIG.47 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 41. As shown in this figure, the built-in antenna for a radio communication terminal according to Embodiment 41 is constructed of base plate 11, balanced/unbalanced conversion circuit 13, power supply terminals 14 and dipole antenna 421. The two antenna elements making up dipole antenna 421 are folded near the center and the parts of the folded antenna elements including power supply terminals 14 are bar-shaped and the other parts without power supply terminals 14 are rectangular-wave-shaped. The two antenna elements are placed in such a way that their respective bar-shaped parts form a straight line.

[0232] Dipole antenna 421 is mounted in such a way that the longitudinal direction of the rectangular-wave-shaped antenna element is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal. On the other hand, the axial direction of the bar-shaped antenna element is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal.

[0233] This allows dipole antenna 421 to receive vertical polarized waves parallel to the longitudinal direction of the rectangular-wave-shaped antenna element and horizontal polarized waves parallel to the axial direction of the bar-shaped antenna element in a free space. Furthermore, during a conversation, the human body acts as a reflector, and therefore dipole antenna 421 has directivity opposite to the human body.

[0234] Then, the operation of the built-in antenna for a radio communication terminal in the above configuration will be explained. An unbalanced signal from the transmission/reception circuit above is converted to a balanced signal by balanced/unbalanced conversion circuit 13 and sent to dipole antenna 421. The rectangular-wave-shaped part of dipole antenna 421 supplied with power in this way mainly sends vertical polarized waves parallel to the longitudinal direction of this rectangular-wave-shaped part. Furthermore, during reception, dipole antenna 421 receives vertical polarized waves parallel to the longitudinal direction above. On the other hand, the bar-shaped part of the antenna element making up dipole antenna 421 supplied with power in this way mainly sends parallel polarized waves parallel to the axial direction of this part.
Furthermore, during reception, horizontal polarized waves parallel to the axial direction of this part are received. In a free space, vertical polarized waves and horizontal polarized waves are received from all directions centered on the dipole antenna and during a conversation, the human body acts as a reflector, and therefore vertical polarized waves and horizontal polarized waves from the direction opposite to the human body are mainly received.

[0235] The signal above (balanced signal) received from dipole antenna 421 is sent to the transmission/reception circuit above via balanced/unbalanced conversion circuit 13. Here, the current that flows into base plate 11 is suppressed to a minimum by above-described balanced/unbalanced conversion circuit 13, and therefore the antenna operation by base plate 11 is prevented. This minimizes the reduction of gain caused by influences from the human body.

[0236] Thus, this embodiment also achieves effects similar to those of Embodiment 39. Furthermore, by mainly receiving vertical polarized waves using the bar-shaped antenna element and mainly receiving horizontal polarized waves using the rectangular-wave-shaped antenna element, it is possible to change the ratio of polarization of vertical polarized waves to horizontal polarized waves as appropriate and thereby receive at a ratio of polarization according to the purpose of use of the antenna.

(Embodiment 42)

[0237] Embodiment 42 is a mode in which the configuration of dipole antenna 421 in Embodiment 41 is changed. Embodiment 42 is the same as Embodiment 41 except for the configuration of dipole antenna 421, and therefore detailed explanations thereof will be omitted.
Differences of the built-in antenna for a radio communication terminal according to this embodiment from Embodiment 41 will be explained below using FIG.48. The parts similar to those in Embodiment 41 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0238] FIG.48 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 42. As shown in this figure, the built-in antenna for a radio communication terminal according to Embodiment 42 is constructed of base plate 11, balanced/unbalanced conversion circuit 13, power supply terminals 14 and dipole antenna 431. The two antenna elements making up dipole antenna 431 are folded near the center and the parts of the folded antenna elements including the power supply terminals 14 are rectangular-wave-shaped and the other parts without power supply terminals 14 are bar-shaped. The two antenna elements are placed in such a way that the longitudinal directions of the rectangular-wave-shaped parts form a straight line.

[0239] Dipole antenna 431 is mounted in such a way that the longitudinal directions of the rectangular-wave-shaped parts are quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal. On the other hand, the axial directions of the bar-shaped parts are quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal.

[0240] This allows dipole antenna 431 to receive vertical polarized waves parallel to the longitudinal direction of the rectangular-wave-shaped antenna element and horizontal polarized waves parallel to the axial direction of the bar-shaped antenna element in a free space. Furthermore, during a conversation, the human body acts as a reflector, and therefore dipole antenna 401 has directivity opposite to the human body.

[0241] Thus, this embodiment also achieves effects similar to those of Embodiment 39. Furthermore, by mainly receiving vertical polarized waves using the bar shaped antenna element and mainly receiving horizontal polarized waves using the rectangular-wave-shaped antenna element, it is possible to change the ratio of polarization of vertical polarized waves to horizontal polarized waves as appropriate and thereby receive at a ratio of polarization according to the purpose of use of the antenna.

(Embodiment 43)

[0242] Embodiment 43 is a mode in which the configuration of the dipole antenna used in each embodiment above is changed.

[0243] FIG.49 is a schematic diagram showing a configuration of dipole antenna 441 used in Embodiment 43. As shown in this figure, the folded-dipole antenna 441 according to Embodiment 43 is formed in such a way that inductance element 442 is inserted between the terminals of the rectangular-wave-shaped antenna elements and power supply terminals 14.

[0244] The folded-dipole antenna 441 in the above configuration is applicable as the built-in antenna for a radio communication terminal or as the dipole antenna making up the diversity antenna according to Embodiments 1 to 11, Embodiments 17 to 42, which will be described later and Embodiments 49 to 59, which will be described later.

[0245] Thus, applying dipole antenna 441 as the dipole antenna to the configuration of each embodiment above can attain effects similar to those in each embodiment above and further increase impedance and perform impedance matching easily. Moreover, using dipole antenna 441 in the above configuration as the dipole antenna makes it possible to implement a double-frequency antenna.

(Embodiment 44)

[0246] Embodiment 44 is a mode in which the configuration of the dipole antenna used in Embodiment 12 is changed. Embodiment 44 is the same as Embodiment 12 except for the configuration of the dipole antenna.

[0247] FIG.50 is a schematic diagram showing a configuration of dipole antenna 451 used in Embodiment 44. As shown in this figure, the folded-dipole antenna 451 according to Embodiment 44 is formed in such a way that two rectangular-wave-shaped antenna elements are placed in parallel, these two rectangular-wave-shaped antenna elements placed in parallel are connected near the center using capacitance elements 451 and the ends of these two antenna elements are shorted.

[0248] The folded-dipole antenna 451 in the above configuration is applicable as the built-in antenna for a radio communication terminal or as the dipole antenna making up the diversity antenna according to Embodiments 1 to 11, Embodiments 17 to 42, which will be described later and Embodiments 49 to 59, which will be described later.

[0249] Thus, this embodiment can also obtain a configuration similar to that of Embodiment 12. Moreover, using dipole antenna 441 in the above configuration as the dipole antenna makes it possible to implement a double-frequency antenna.

(Embodiment 45)

[0250] Embodiment 45 is a mode in which the configuration of the dipole antenna used in the embodiment above is changed. Embodiment 45 is the same as the embodiment above except for the configuration of the dipole antenna. The parts in FIG.51 similar to those in the embodiment above are assigned the same reference numerals and detailed explanations thereof will be omitted.

[0251] FIG.51 is a schematic diagram showing a configuration of folded-dipole antenna 461 used in Embodiment 45 . As shown in this figure, the folded-dipole antenna 461 according to Embodiment 45 is formed in such a way that inductance elements 462 are placed between the ends of the rectangular-wave-shaped antenna elements and power supply terminals 14.

[0252] The folded-dipole antenna 461 in the above configuration is applicable as the built-in antenna for a radio communication terminal or as the dipole antenna making up the diversity antenna according to Embodiments 1 to 11, Embodiments 17 to 42, which will be described later and Embodiments 49 to 59, which will be described later.

[0253] Thus, this embodiment can also obtain a configuration similar to that of Embodiment 14. Moreover, using dipole antenna 461 in the above configuration as the dipole antenna makes it possible to implement a double-frequency antenna.

(Embodiment 46)

[0254] Embodiment 46 is a mode in which the configuration of the dipole antenna used in Embodiment 15 is changed. Embodiment 46 is the same as Embodiment 15 except for the configuration of the dipole antenna. The parts in FIG.52 similar to those in the embodiment above are assigned the same reference numerals and detailed explanations thereof will be omitted.

[0255] FIG.52 is a schematic diagram showing a configuration of folded-dipole antenna 471 used in Embodiment 46. As shown in this figure, the folded-dipole antenna 471 according to Embodiment 46 is formed in such a way that the two spiral antenna elements of the dipole antenna explained in the above embodiment are placed in parallel, these two antennal elements placed in parallel are connected by capacitance 472 near the center and the ends are shorted.

[0256] The folded-dipole antenna 471 in the above configuration is applicable as the built-in antenna for a radio communication terminal or as the dipole antenna making up the diversity antenna according to Embodiments 1 to 11, Embodiments 17 to 42, which will be described later and Embodiments 49 to 59, which will be described later.

[0257] Thus, this embodiment can also obtain a configuration similar to that of Embodiment 15. Moreover, using dipole antenna 471 in the above configuration as the dipole antenna makes it possible to implement a double-frequency antenna.

(Embodiment 47)

[0258] Embodiment 47 is a mode in which the configuration of the dipole antenna used in the embodiment above is changed. Embodiment 47 is the same as the embodiment above except for the configuration of the dipole antenna. The parts in FIG.53 similar to those in the embodiment above are assigned the same reference numerals and detailed explanations thereof will be omitted.

[0259] FIG.53 is a schematic diagram showing a configuration of dipole antenna 481 used in Embodiment 47. As shown in this figure, the dipole antenna 481 according to Embodiment 47 is formed in such a way that the two antenna elements of the rectangular-wave-shaped dipole antenna explained in the above embodiment are placed in parallel, power supply terminals 14 of these two antennal elements placed in parallel are shorted.

[0260] The folded-dipole antenna 481 in the above configuration is applicable as the built-in antenna for a radio communication terminal or as the dipole antenna making up the diversity antenna according to Embodiments 1 to 11, Embodiments 17 to 42, which will be described later and Embodiments 49 to 59, which will be described later.

[0261] Thus, this embodiment can also obtain a configuration similar to that of Embodiment 12. Moreover, using dipole antenna 481 in the above configuration as the dipole antenna makes it possible to implement a double-frequency antenna.

(Embodiment 48)

[0262] Embodiment 48 is a mode in which the configuration of the dipole antenna used in Embodiment 12 is changed. Embodiment 48 is the same as Embodiment 12 except for the configuration of the dipole antenna. The parts in FIG.54 similar to those in the embodiment above are assigned the same reference numerals and detailed explanations thereof will be omitted.

[0263] FIG.54 is a schematic diagram showing a configuration of dipole antenna 491 used in Embodiment 48. As shown in this figure, the dipole antenna 491 according to Embodiment 48 is formed in such a way that the two antenna elements of the spiral dipole antenna explained in Embodiment 14 are placed in parallel, power supply terminals 14 of these two antennal are shorted.

[0264] The folded-dipole antenna 491 in the above configuration is applicable as the built-in antenna for a radio communication terminal or as the dipole antenna making up the diversity antenna according to Embodiments 1 to 11, Embodiments 17 to 42, which will be described later and Embodiments 49 to 59, which will be described later.

[0265] Thus, this embodiment can also obtain a configuration similar to that of Embodiment 14. Moreover, using dipole antenna 491 in the above configuration as the dipole antenna makes it possible to implement a double-frequency antenna.

[0266] By the way, dipole antennas 441, 451, 461, 471, 481 and 491 above have a self-balancing action, and therefore a configuration without balanced/unbalanced conversion circuit 13 can also be used in Embodiment 43 to Embodiment 48.

[0267] Embodiment 1 to Embodiment 48 describe cases where antenna elements are rectangular-wave-shaped, but the present invention is not limited to this, and the antenna elements can also be bar-shaped depending on the transmission/reception frequency, the shape and size of the radio equipment that incorporates antennas.

(Embodiment 49)

[0268] Embodiment 49 is a mode in which the configuration of the dipole antenna used in Embodiment 1 is changed and a passive element is provided. Embodiment 49 is the same as Embodiment 1 except for the configuration of the dipole antenna and the passive element. The parts in FIG.55 similar to those in the embodiment above are assigned the same reference numerals and detailed explanations thereof will be omitted.

[0269] FIG.55 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 49 of the present invention. As shown in this figure, the built-in antenna for a radio communication terminal according to Embodiment 49 is constructed of base plate 11, dipole antenna 12, balanced/unbalanced conversion circuit 13 and power supply terminals 14. The built-in antenna for a radio communication terminal according to this embodiment is incorporated in a communication terminal apparatus.

[0270] FIG.56 is a front view showing the appearance of the communication terminal apparatus incorporating the built-in antenna for a radio communication terminal according to this embodiment. As shown in this figure, speaker 511 is provided at the top of the main plane of package 510. Below speaker 511 is display 512 that displays various kinds of information such as telephone numbers to be called and operation menu. At the bottom of the main plane of package 510 is microphone 513 to catch voice of the user. Furthermore, built-in antenna 514 for a radio communication terminal according to this embodiment is incorporated in package 510. This built-in antenna 514 for a radio communication terminal is installed in such a way that base plate 11 is placed quasi-parallel to the main plane.

[0271] The components of the built-in antenna for a radio communication terminal according to this embodiment will be explained below with reference to FIG.55.

[0272] Dipole antenna 501 is constructed of two bar-shaped antenna elements. The two antenna elements making up dipole antenna 501 are placed in such a way that their respective axial directions form one quasi-straight line. Furthermore, dipole antenna 501 is mounted in such a way that the axial directions of the antenna elements are quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal. Since the radio communication terminal is used in a state shown in FIG.58, dipole antenna 501 is provided in such a way that the axial directions of the antenna elements are quasi-perpendicular to the horizontal plane. Thus, dipole antenna 501 mainly receives vertical polarized waves parallel to the axial direction in a free space. Furthermore, since the human body operates as a reflector during a conversation, dipole antenna 501 has directivity opposite to the direction of the human body.

[0273] Passive element 502 is bar-shaped. Passive element 502 is quasi-parallel to the axial directions of the antenna elements making up dipole antenna 501 and the plane (reference plane) containing the antenna elements making up dipole antenna 501 and passive element 502 intersects with the plane of base plate 11 at quasi-right angles. Since base plate 11 is provided quasi-parallel to the main plane of package 510, the reference plane also intersects with the main plane of package 510 at quasi-right angles. FIG.57 is a cross-sectional view viewed from the direction of arrow A of FIG.55 of the built-in antenna for a radio communication terminal according to this embodiment. As is apparent from this figure, passive element 502 is placed in such a way that the plane (reference plane) containing the antenna elements making up dipole antenna 501 and passive element 502 intersects with the plane of base plate 11 at quasi-right angles. As a result of this placement, the plane containing the antenna elements making up dipole antenna 501 and passive element 502 also intersects with the main plane of package 510 shown in FIG. 56 at quasi-right angles.

[0274] Next, the operation of the built-in antenna for a radio communication terminal in the above configuration will be explained. An unbalanced signal from the transmission/reception circuit above is converted to a balanced signal by balanced/unbalanced conversion circuit 13 and then sent to dipole antenna 501. Dipole antenna 501 supplied with power in this way mainly sends vertical polarized waves, parallel to this axial direction.

[0275] A transmission signal sent from dipole antenna 501 has directivity along the reference plane and normal to the main plane of package 510 by changing the length of dipole antenna 501, length of passive element 502 and distance between dipole antenna 501 and passive element 502 as appropriate. The radio communication terminal is assumed to be used in a state shown in FIG.58. In this case, since the main plane of package 510 faces the temporal region of the user's head, the transmission signal is transmitted in the direction opposite to the human body by adjusting the length of dipole antenna 501, length of passive element 502 and distance between dipole antenna 501 and passive element 502 as appropriate.

[0276] On the other hand, during reception, dipole antenna 501 receives vertical polarized waves parallel to the axial directions of the antenna elements. During a conversation, since directivity opposite to the human body is formed by adjusting the length of dipole antenna 501, length of passive element 502 and distance between dipole antenna 501 and passive element 502 as appropriate, of the vertical polarized waves above, the vertical polarized waves from the direction opposite to the human body are mainly received. Furthermore, since the human body acts as a reflector as described above, of the vertical polarized waves above, the vertical polarized waves opposite to the human body are mainly received.

[0277] The signals above received by dipole antenna 501 are sent to the transmission/reception circuit above via balanced/unbalanced conversion circuit 13. Since balanced/unbalanced conversion circuit 13 above minimizes the current that flows into base plate 11, the antenna operation by base plate 11 is prevented. This suppresses the reduction of gain caused by influences from the human body to a minimum.

[0278] Thus, according to this embodiment, directivity opposite to the human body is formed for dipole antenna 501 by adjusting the length of dipole antenna 501, length of passive element 502 and distance between dipole antenna 501 and passive element 502 as appropriate, and therefore it is possible to suppress deterioration of gain by influences from the human body. Furthermore, as in the case of Embodiment 1 above, balanced/unbalanced conversion circuit 13 adjusts impedance appropriately and minimizes an antenna current that flows into base plate 11 and can thereby prevent deterioration of gain of dipole antenna 501.

(Embodiment 50)

[0279] Embodiment 50 is a mode in which the method of mounting dipole antenna 501 and passive element 502 in Embodiment 49 is changed. Since Embodiment 50 is the same as Embodiment 49 except for the method of mounting dipole antenna 501 and passive element 502, detailed explanations thereof will be omitted. Differences of the built-in antenna for a radio communication terminal according to this embodiment from Embodiment 49 will be explained below using FIG. 59. The parts similar to those in Embodiment 49 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0280] FIG.59 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 50. As shown in this figure, the built-in antenna for a radio communication terminal according to Embodiment 2 is constructed of base plate 11, balanced/unbalanced conversion circuit 13, power supply terminals 14, dipole antenna 501 and passive element 502.

[0281] Dipole antenna 501 is mounted in such a way that the axial directions of the antenna elements are quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal. That is, this embodiment is different from Embodiment 49 in that dipole antenna 501 is provided quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal.

[0282] Thus, according to this embodiment, it is possible to suppress deterioration of gain caused by influences from the human body and also receive horizontal polarized waves parallel to the axial direction during reception. On the other hand, a signal sent from the other end of communication is a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, when there are more horizontal polarized waves, the axial direction of the antenna matches the polarization plane, making it possible to increase the reception gain.

(Embodiment 51)

[0283] Embodiment 51 is a mode in which the configuration and method of mounting dipole antenna 501 and passive element 502 in Embodiment 49 are changed. Since Embodiment 51 is the same as Embodiment 49 except for the configuration and method of mounting dipole antenna 501 and passive element 502, detailed explanations thereof will be omitted. Differences of the built-in antenna for a radio communication terminal according to this embodiment from Embodiment 49 will be explained below using FIG.60. The parts similar to those in Embodiment 49 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0284] FIG.60 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 51. As shown in this figure, the built-in antenna for a radio communication terminal according to Embodiment 51 is constructed of base plate 11, balanced/unbalanced conversion circuit 13, power supply terminals 14, dipole antenna 551 and passive element 552. The two antenna elements making up dipole antenna 551 are placed quasi-perpendicular to each other. Passive element 552 is folded near the center and the folded sides are formed in such a way as to intersect with each other at right angles.

[0285] Dipole antenna 551 is mounted in such a way that one antenna element is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal and the other antenna element is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal. Furthermore, passive element 552 is mounted in such a way that one of the folded sides is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal and the other side is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal.

[0286] Next, the operation of the built-in antenna for a radio communication terminal in the above configuration will be explained. An unbalanced signal from the transmission/reception circuit of the radio communication terminal is converted to a balanced signal by balanced/unbalanced conversion circuit 13 and then sent to dipole antenna 551. The antenna element placed quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal making up dipole antenna 551 supplied with power in this way mainly sends vertical polarized waves parallel to the axial direction of this antenna element. On the other hand, the antenna element placed quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal making up dipole antenna 551 sends horizontal polarized waves parallel to the axial direction of this antenna element.

[0287] A transmission signal sent from dipole antenna 551 has directivity along the reference plane and normal to the main plane of package 510 by changing the length of dipole antenna 551, length of passive element 552 and distance between dipole antenna 551 and passive element 552 as appropriate. The radio communication terminal is assumed to be used in a state shown in FIG.58. In this case, since the main plane of package 510 faces the temporal region of the user's head, the transmission signal is transmitted in the direction opposite to the human body by adjusting the length of dipole antenna 551, length of passive element 502 and distance between dipole antenna 551 and passive element 552 as appropriate.

[0288] On the other hand, during reception, the antenna element making up dipole antenna 551 placed quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal mainly receives vertical polarized waves parallel to the axial direction of this antenna element. On the other hand, the antenna element making up dipole antenna 551 placed quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal mainly receives horizontal polarized waves parallel to the axial direction of this antenna element. Furthermore, during a conversation, since directivity opposite to the human body is formed by adjusting the length of dipole antenna 501, length of passive element 502 and distance between dipole antenna 501 and passive element 502 as appropriate, of the reception waves above, electromagnetic waves from the direction opposite to the human body are mainly received. Furthermore, since the human body acts as a reflector as described above, of the electromagnetic waves above, electromagnetic waves opposite to the human body are mainly received.

[0289] Thus, according to this embodiment, it is possible to suppress deterioration of gain caused by influences from the human body and receive both vertical polarized waves and horizontal polarized waves parallel to the axial direction during reception. On the other hand, a signal sent from the other end of communication is a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, even if there are more vertical polarized waves or more horizontal polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the polarization plane of the signal sent from the other end of communication, allowing reception gain to be increased.

(Embodiment 52)

[0290] Embodiment 52 is a mode in which the configuration and method of mounting dipole antenna 501 and passive element 502 in Embodiment 49 are changed. Since Embodiment 52 is the same as Embodiment 49 except for the configuration and method of mounting dipole antenna 501 and passive element 502, detailed explanations thereof will be omitted. Differences of the built-in antenna for a radio communication terminal according to this embodiment from Embodiment 49 will be explained below using FIG.61. The parts similar to those in Embodiment 49 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0291] FIG.61 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 52. As shown in this figure, the built-in antenna for a radio communication terminal according to Embodiment 52 is constructed of base plate 11, balanced/unbalanced conversion circuit 13, power supply terminals 14, dipole antenna 561 and passive element 562. The two antenna elements making up dipole antenna 561 are folded near the center and the folded sides are formed in such a way as to intersect with each other at right angles. Passive element 552 is folded at a point in a predetermine distance from one end and the folded sides are formed in such a way to intersect at right angles. Furthermore, the sides including both ends of passive element 552 are parallel to each other and the side not including the both ends is formed to be longer than the width of base plate 11.

[0292] Each antenna element making up dipole antenna 561 in the above configuration is mounted in such a way that the sides including power supply terminals 14 are quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal and the sides not including power supply terminals 14 are quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal. Furthermore, passive element 562 is mounted in such a way that the sides including the ends are quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal and the side not including the ends is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal.

[0293] Next, the operation of the built-in antenna for a radio communication terminal in the above configuration will be explained. An unbalanced signal from the transmission/reception circuit above provided for the radio communication terminal is converted to a balanced signal by balanced/unbalanced conversion circuit 13 and then sent to dipole antenna 561. The parts of the antenna elements making up dipole antenna 561 placed quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal supplied with power in this way mainly send vertical polarized waves. On the other hand, the parts of the antenna elements making up dipole antenna 561 placed quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal send horizontal polarized waves.

[0294] A transmission signal sent from dipole antenna 561 has directivity along the reference plane and normal to the main plane of package 510 by changing the length of dipole antenna 561, length of passive element 562 and distance between dipole antenna 561 and passive element 552 as appropriate. The radio communication terminal is assumed to be used in a state shown in FIG.58. In this case, since the main plane of package 510 faces to the temporal region of the user's head, the transmission signal is transmitted in the direction opposite to the human body by adjusting the length of dipole antenna 561, length of passive element 562 and distance between dipole antenna 561 and passive element 562 as appropriate.

[0295] Here, the emission characteristic of the built-in antenna for a radio communication terminal in the above configuration in a free space will be explained with reference to FIG.62. FIG.62 illustrates actual measured values of the emission characteristic of the built-in antenna for a radio communication terminal according to this embodiment in a free space. Suppose the size of base plate 11 is 27 × 114 mm, the length of the side of the antenna element making up dipole antenna 561 placed quasi-parallel to the upper surface (horizontal plane) of the package of the radio communication terminal apparatus is 33 mm, the length of the part of the antenna element making up dipole antenna 561 placed quasi-perpendicular to the upper surface (horizontal plane) of the package of the radio communication terminal apparatus is 17 mm and the distance of dipole antenna 12 from the human body is 4 m. In FIG.62, the direction at 0° viewed from the origin corresponds to the direction of the human body viewed from dipole antenna 561 in FIG.61.

[0296] As is apparent from FIG.62, by adjusting the length of dipole antenna 561, length of passive element 562 and distance between dipole antenna 561 and passive element 562 as appropriate, the built-in antenna for a radio communication terminal according to this embodiment has directivity opposite to the direction of the human body.

[0297] Then, the emission characteristic of the built-in antenna for a radio communication terminal in the above configuration will be explained with reference to FIG. 63. FIG.63 illustrates actual measured values of the emission characteristic of the built-in antenna for a radio communication terminal during a conversation. The sizes of the components are the same as those when the emission characteristic shown in FIG.62 are measured. In FIG.63, the direction at 0° viewed from the origin corresponds to the direction of the human body viewed from dipole antenna 561 in FIG.63.

[0298] As is apparent from FIG.63, by adjusting the length of dipole antenna 561, length of passive element 562 and distance between dipole antenna 561 and passive element 562 as appropriate, the built-in antenna for a radio communication terminal according to this embodiment has directivity opposite to the direction of the human body. This makes it possible to suppress deterioration of gain caused by influences from the human body during transmission and thereby achieve higher gain than the conventional example shown in FIG.3B.

[0299] Thus, according to this embodiment, it is possible to suppress deterioration of gain caused by influences from the human body and receive both vertical polarized waves and horizontal polarized waves parallel to the axial direction during reception. On the other hand, a signal sent from the other end of communication is a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, when there are more vertical polarized waves or more horizontal polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the polarization plane of the signal sent from the other end of communication, allowing reception gain to be increased.

[0300] Embodiment 53 to Embodiment 59 are modes in which a diversity antenna is implemented using the built-in antenna for a radio communication terminal in Embodiment 49 to Embodiment 52.

(Embodiment 53)

[0301] Embodiment 53 is a mode in which a diversity antenna is implemented using the built-in antenna for a radio communication terminal in Embodiment 49. The diversity antenna for a radio communication terminal in this embodiment will be explained using FIG.64. The parts similar to those in Embodiment 49 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0302] FIG.64 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 53. FIG.64 shows the configuration of the built-in antenna for a radio communication terminal in Embodiment 49 with additional monopole antenna 61.

[0303] Here, suppose one antenna making up the diversity antenna is dipole antenna 501 in Embodiment 49 and used for reception only. Also suppose the other antenna making up the diversity antenna is monopole antenna 61 and used for both transmission and reception.

[0304] In the diversity antenna for a radio communication terminal in the above configuration, only monopole antenna 61 operates during transmission and dipole antenna 501 and monopole antenna 61 operate during reception to carry out diversity reception.

[0305] Thus, according to this embodiment, dipole antenna 501 in Embodiment 49 is used as the diversity antenna, which makes it possible to provide a high gain diversity antenna for a radio communication terminal with little influence from the human body.

(Embodiment 54)

[0306] Embodiment 54 is a mode in which the configuration of the monopole antenna in Embodiment 53 is changed. The diversity antenna for a radio communication terminal according to this embodiment will be explained using FIG.65. The same configurations as those in Embodiment 53 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0307] FIG.65 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 54. As shown in this figure, the diversity antenna for a radio communication terminal according to Embodiment 54 is constructed of dipole antenna 501, balanced/unbalanced conversion circuit 13, power supply terminals 14 and monopole antenna 71. Monopole antenna 71 is constructed of rectangular-wave-shaped antenna elements.

[0308] In the diversity antenna for a radio communication terminal in the above configuration, only monopole antenna 71 operates during transmission and dipole antenna 501 and monopole antenna 71 operate during reception to carry out diversity reception.

[0309] Thus, according to this embodiment, dipole antenna 501 in Embodiment 49 is used as the diversity antenna, which makes it possible to provide a high gain diversity antenna for a radio communication terminal with little influence from the human body.

(Embodiment 55)

[0310] Embodiment 55 is a mode in which the configuration of the monopole antenna in Embodiment 53 is changed. The diversity antenna for a radio communication terminal according to this embodiment will be explained using FIG.66. The same configurations as those in Embodiment 53 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0311] FIG.66 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 55. As shown in this figure, the diversity antenna for a radio communication terminal according to Embodiment 55 is constructed of dipole antenna 501, balanced/unbalanced conversion circuit 13, power supply terminals 14 and monopole antenna 81. Monopole antenna 81 is constructed of a spiral antenna element.

[0312] In the diversity antenna for a radio communication terminal in the above configuration, only monopole antenna 81 operates during transmission and dipole antenna 501 and monopole antenna 81 operate during reception to carry out diversity reception.

[0313] Thus, this embodiment configured as shown above can also attain effects similar to those in Embodiment 54.

(Embodiment 56)

[0314] Embodiment 56 is a mode in which a diversity antenna is implemented using the built-in antenna for a radio communication terminal in Embodiment 49. The diversity antenna for a radio communication terminal according to this embodiment will be explained using FIG. 67. The same configurations as those in Embodiment 49 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0315] FIG.67 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 56. As shown in this figure, this embodiment has the configuration of the built-in antenna for a radio communication terminal according to Embodiment 49 with dipole antenna 621 and passive element 622 added to the side of base plate 11. Dipole antenna 621 has a configuration similar to dipole antenna 501.

[0316] Here, suppose one antenna making up the diversity antenna is dipole antenna 501 in Embodiment 49 and used for reception only. Suppose the other antenna making up the diversity antenna is dipole antenna 621 and used for both transmission and reception.

[0317] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 621 operates during transmission and dipole antenna 501 and dipole antenna 621 operate during reception to carry out diversity reception.

[0318] Thus, according to this embodiment, dipole antenna 501 in Embodiment 1 and dipole antenna 621 are used as the diversity antenna, and it is therefore possible to provide a high gain diversity antenna for a radio communication terminal with little influence from the human body.

(Embodiment 57)

[0319] Embodiment 57 is a mode in which the method of mounting dipole antenna 621 and passive element 622 in Embodiment 56 is changed. Since Embodiment 57 is the same as Embodiment 56 except for the method of mounting dipole antenna 621 and passive element 622, detailed explanations thereof will be omitted. Differences of the built-in antenna for a radio communication terminal according to this embodiment from Embodiment 56 will be explained below using FIG.67. The parts similar to those in Embodiment 56 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0320] FIG.68 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 57. As shown in this figure, dipole antenna 621 is mounted in such a way that its axial direction is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal. Furthermore, passive element 622 is also mounted in such a way that its axial direction is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal. That is, this embodiment differs from Embodiment 56 in that the axial direction of dipole antenna 621 is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal and the axial direction of passive element 622 is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal. As a result, dipole antenna 621 is provided in such a way that its axial direction is quasi-parallel to the horizontal plane during a conversation.

[0321] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 621 operates during transmission and dipole antenna 501 and dipole antenna 621 operate during reception to carry out diversity reception.

[0322] Thus, dipole antenna 501 can suppress deterioration of gain and at the same time mainly receive vertical polarized waves parallel to the axial direction of the antenna element. Furthermore, dipole antenna 621 can not only suppress deterioration of gain but also mainly receive horizontal polarized waves parallel to the axial direction of the antenna element. On the other hand, the signal sent from the other end of communication is often a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, even if there are either more vertical polarized waves or more horizontal polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the plane of polarization of the signal sent from the other end of communication and can thereby increase the reception gain.

[0323] Thus, this embodiment uses dipole antenna 501 in Embodiment 49 and dipole antenna 621 as the diversity antenna, and can thereby provide a high gain diversity antenna for a radio communication terminal with little influence from the human body.

(Embodiment 58)

[0324] As shown in FIG.69, Embodiment 58 is a mode in which the dipole antenna used in Embodiment 56 for both transmission and reception is changed to dipole antenna 551 shown in Embodiment 51 and the passive element is changed to passive element 552 shown in Embodiment 51. Embodiment 58 is the same as Embodiment 56 except for the configurations and the method of mounting of the dipole antenna and passive element. The same parts in FIG.69 as those in Embodiment 56 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0325] FIG.69 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 58. As shown in this figure, dipole antenna 551 is mounted in such a way that the axial direction of one antenna element is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal and the axial direction of the other antenna element is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal.

[0326] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 551 operates during transmission and dipole antenna 501 and dipole antenna 551 operate during reception to carry out diversity reception.

[0327] Thus, dipole antenna 551 can suppress deterioration of gain and at the same time mainly receive vertical polarized waves and horizontal polarized waves parallel to the axial direction of the antenna element. Furthermore, dipole antenna 501 can not only suppress deterioration of gain but also mainly receive vertical polarized waves parallel to the axial direction of the antenna element. On the other hand, the signal sent from the other end of communication is often a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, even if there are either more vertical polarized waves or more horizontal polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the plane of polarization of the signal sent from the other end of communication and can thereby increase the reception gain.

[0328] Thus, this embodiment uses dipole antenna 501 in Embodiment 49 and dipole antenna 551 in Embodiment 51 as the diversity antenna, and can thereby provide a high gain diversity antenna for a radio communication terminal with little influence from the human body.

(Embodiment 59)

[0329] As shown in FIG.70, Embodiment 59 is a mode in which dipole antenna 501 in Embodiment 58 used for reception only is changed to dipole antenna 651 having the same configuration as dipole antenna 551 shown in Embodiment 51 and passive element 502 is changed to passive element 652 shown in Embodiment 51. Embodiment 59 is the same as Embodiment 59 except for the configurations and the method of mounting of the dipole antenna and passive element. The same parts in FIG.17 as those in Embodiment 59 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0330] FIG.70 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 59. As shown in this figure, both dipole antenna 551 and dipole antenna 651 are mounted in such a way that the axial direction of one antenna element is quasi-perpendicular to the upper surface (horizontal plane) of the radio communication terminal and the axial direction of the other antenna element is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal.

[0331] In the diversity antenna for a radio communication terminal in the above configuration, only dipole antenna 551 operates during transmission and dipole antenna 551 and dipole antenna 651 operate during reception to carry out diversity reception.

[0332] Thus, dipole antenna 551 can suppress deterioration of gain and at the same time mainly receive vertical polarized waves and horizontal polarized waves parallel to the axial direction of the antenna element. Furthermore, dipole antenna 651 can not only suppress deterioration of gain but also mainly receive vertical polarized waves parallel to the axial direction of the antenna element. On the other hand, the signal sent from the other end of communication is often a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, even if there are either more vertical polarized waves or more horizontal polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the plane of polarization of the signal sent from the other end of communication and can thereby increase the reception gain.

[0333] Thus, this embodiment uses dipole antenna 651 and dipole antenna 551 in Embodiment 51 as the diversity antenna, and can thereby provide a high gain diversity antenna for a radio communication terminal with little influence from the human body.

[0334] By the way, Embodiment 49 to Embodiment 59 above describe the case where each antenna element of the dipole antenna is bar-figured, but the present invention is not limited to this and one or both antenna elements can also be rectangular-wave-shaped.

[0335] Embodiment 49 to Embodiment 59 describe the case where the passive element is bar-shaped, but the present invention is not limited to this and the passive element can also be rectangular-wave-shaped or spiral.

[0336] As explained above, the present invention performs impedance matching between the antenna elements and power supply means appropriately, and can thereby provide a high gain built-in antenna for radio communication terminal with little influence from the human body. Moreover, using a rectangular-wave-shaped antenna element of the dipole antenna makes it possible to provide a small built-in antenna for radio communication terminal.

[0337] Furthermore, directivity opposite to the human body is formed for the dipole antenna by adjusting the length of the dipole antenna, length of passive element and distance between the dipole antenna and passive element as appropriate, and therefore it is possible to suppress deterioration of gain caused by influences from the human body.

[0338] Furthermore, directivity opposite to the human body is formed for dipole antenna by adjusting the length of the dipole antenna, length of passive element and distance between the dipole antenna and passive element as appropriate, and therefore it is possible to suppress deterioration of gain of the dipole antenna by influences from the human body.

(Embodiment 60)

[0339] FIG.71 a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 60. Each element shown in the figure is incorporated in the package of the radio communication terminal, but an overall view of the radio communication terminal will be omitted here for brevity of explanations. The built-in antenna for a radio communication terminal according to this embodiment is constructed of base plate 11, loop antenna 601 and balanced/unbalanced conversion circuit 13. X, Y and Z denote their respective coordinate axes. The components will be explained below.

[0340] Base plate 11 is a tabular grounded conductor and is mounted quasi-parallel to the plane (vertical plane) of the radio communication terminal provided with operation buttons, a display and speaker, etc. which are not shown.

[0341] Loop antenna 601 is mounted in such a way that this loop plane is quasi-perpendicular to the plane provided with the above-described display and speaker, etc. and the loop plane is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal. As a result, loop antenna 601 is provided in such a way that this loop plane is quasi-perpendicular to the human body during a conversation. In this way, virtual intensity of magnetic field is in phase with real intensity of magnetic field on the loop plane, which increases the gain of loop antenna 601.

[0342] Furthermore, loop antenna 601 is mounted in such a way that this loop plane is quasi-parallel to the upper surface (horizontal plane) of the radio communication terminal. As a result, loop antenna 601 is mounted in such a way that the loop plane is quasi-parallel to the horizontal plane. This makes loop antenna 601 mainly receive horizontal polarized waves parallel to the loop plane in a free space. During a conversation, since the human body acts as a reflector, loop antenna 601 has directivity opposite to the human body, that is, directivity toward the front of the sheet in FIG.71.

[0343] Furthermore, loop antenna 601 is provided in such a way that this circumference is equal to or shorter than quasi-one wavelength of the reception wave. The loop antenna has a nature that when its circumference is longer than one wavelength of the reception wave, the phase of the current that flows into the loop antenna is inverted, and therefore directivity is split. Therefore, loop antenna 601 according to this embodiment is provided in such a way that its circumference is equal to or shorter than quasi-one wavelength of the reception wave, which prevents directivity from being split.

[0344] Balanced/unbalanced conversion circuit 13 is a conversion circuit with an impedance conversion ratio of 1 to 1 or n to 1 (n: integer) and is attached to the power supply terminals of the dipole antenna. More specifically, one terminal of balanced/unbalanced conversion circuit 13 is connected to a transmission/reception circuit, which is not shown and the other terminal is attached to base plate 11. In this way, balanced/unbalanced conversion circuit 13 performs impedance conversion between loop antenna 601 and the transmission/reception circuit above, making it possible to obtain impedance matching between the two appropriately. Moreover, balanced/unbalanced conversion circuit 13 converts an unbalanced signal of the transmission/reception circuit above to a balanced signal and supplies to loop antenna 601, thus minimizing the current that flows into base plate 11. This prevents the action of base plate 11 as an antenna, and can thereby prevent reduction of the gain of loop antenna 601 caused by influences from the human body.

[0345] Next, the operation of the built-in antenna for a radio communication terminal in the above configuration will be explained. An unbalanced signal from the transmission/reception circuit above is converted to a balanced signal by balanced/unbalanced conversion circuit 13 and then sent to loop antenna 601. Loop antenna 601 supplied with power in this way mainly receives horizontal polarized waves parallel to this loop plane. In a free space, horizontal polarized waves from all directions centered on the loop antenna are received and, since the human body acts as a reflector as described above during a conversation, of the horizontal polarized waves above, horizontal polarized waves opposite to the human body are mainly received.

[0346] The signals above received by loop antenna 601 (balanced signals) are sent to the transmission/reception circuit above via balanced/unbalanced conversion circuit 13. Since balanced/unbalanced conversion circuit 13 above minimizes the current that flows into base plate 11, the antenna operation by base plate 11 is prevented. This minimizes reduction of the gain caused by influences from the human body.

[0347] Here, the reception characteristic of the built-in antenna for a radio communication terminal in the above configuration will be explained with reference to FIG.72. FIG.72 illustrates actual measured values of the reception characteristic of the built-in antenna for a radio communication terminal according to Embodiment 60 during a conversation. Suppose the size of base plate 11 is 120×36 mm, the size of loop antenna 601 is 63×5 mm, the distance of loop antenna 601 from the human body is 5 mm, and the frequency is 2180 MHz. In FIG.72, the direction at 270° viewed from the origin corresponds to the direction of the human body viewed from loop antenna 601 in FIG.6.

[0348] As is apparent from FIG.72, under the influence of the human body that acts as a reflector, loop antenna 601 has directivity opposite to the direction of the human body and not only prevents splitting of directivity for the above-described reason but also maintains a high gain characteristic suppressing deterioration of gain compared to the conventional example shown in FIG.3B.

[0349] Thus, according to this embodiment, providing loop antenna 601 in such a way that the loop plane of loop antenna 601 is quasi-perpendicular to the human body, increasing the gain of loop antenna 601 and that the circumference of loop antenna 601 is equal to or shorter than quasi-one wavelength, thus preventing the splitting of directivity of loop antenna 601, and balanced/unbalanced conversion circuit 13 minimizes an antenna current that flows into base plate 11, preventing deterioration of gain of loop antenna 601 caused by influences from the human body. This makes it possible to provide a high gain built-in antenna for radio communication terminal with little influence from the human body.

(Embodiment 61)

[0350] Embodiment 61 is a mode in which the method of mounting loop antenna 601 in Embodiment 60 is changed. Embodiment 61 is the same as Embodiment 60 except for the method of mounting loop antenna 601, and therefore detailed explanations thereof will be omitted. Differences of the built-in antenna for a radio communicant terminal according to this embodiment from Embodiment 60 will be explained using FIG.73. The parts similar to those in Embodiment 60 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0351] FIG.73 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 61. Loop antenna 611 is mounted in such a way that this loop plane is quasi-perpendicular to the plane provided with operation buttons, a display and speaker, etc., which are not shown of the radio communication terminal and the loop plane above is quasi-parallel to the side of the radio communication terminal (vertical plane) of the radio communication terminal. That is, this embodiment is different from embodiment 60 in that the loop plane of loop antenna 611 is quasi-parallel to the side of the radio communication terminal (vertical plane) of the radio communication terminal. As a result, loop antenna 611 is provided in such a way that this loop plane is quasi-perpendicular to the human body and at the same time quasi-parallel to the vertical plane during a conversation.

[0352] For the above-described reasons, loop antenna 611 can suppress deterioration of gain and mainly receive vertical polarized waves parallel to the loop plane. On the other hand, a signal sent from the other end of communication is a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, when there are more vertical polarized waves, the built-in antenna for a radio communication terminal according to this embodiment matches the polarization plane of the signal sent from the other end of communication, which makes it possible to increase the reception gain.

[0353] According to this embodiment, loop antenna 611 is mounted in such a way that this loop plane is quasi-perpendicular to the human body and the loop plane is quasi-parallel to the side of the radio communication terminal, which makes it possible to suppress deterioration of gain caused by influences from the human body and mainly receive vertical polarized waves. This makes it possible to prevent deterioration of gain due to mismatch with the signal from the other end of communication in the plane of polarization and provide a high gain built-in antenna for a radio communication terminal with little influence from the human body.

(Embodiment 62)

[0354] Embodiment 62 is a mode in which the method of mounting loop antenna 601 in Embodiment 60 is changed. Embodiment 62 is the same as Embodiment 60 except for the method of mounting loop antenna 601, and therefore detailed explanations thereof will be omitted. Differences of the built-in antenna for a radio communicant terminal according to this embodiment from Embodiment 60 will be explained using FIG.74. The parts similar to those in Embodiment 60 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0355] FIG.74 is a schematic diagram showing a configuration of the built-in antenna for a radio communication terminal according to Embodiment 62. As shown in the figure, loop antenna 621 is constructed in such a way that of the four sides making up the loop plane of loop antenna 601 in Embodiment 60, the side facing the power supply terminals is folded at a midpoint and the folded sides form an angle of quasi 90° with each other.

[0356] Loop antenna 621 in the above configuration is mounted in such a way that each folded side is quasi-perpendicular to the plane (vertical plane) provided with operation buttons, a display and speaker, etc. and each folded side is quasi-parallel to the upper surface (horizontal plane) and side (vertical plane) of the radio communication apparatus. That is, this embodiment is different from embodiment 60 in that the loop plane of loop antenna 621 is quasi-parallel to the upper surface and the side of the radio communication terminal of the radio communication terminal. As a result, as in the case of Embodiment 60, loop antenna 621 is provided in such a way that this loop plane is quasi-perpendicular to the human body and at the same time quasi-parallel to the upper surface (horizontal plane) and the side (vertical plane) of the radio communication terminal during a conversation.

[0357] For the above-described reasons, loop antenna 621 can suppress deterioration of gain and mainly receive not only horizontal polarized waves but also vertical polarized waves parallel to the loop plane. On the other hand, as described above, a signal sent from the other end of communication is a mixture of vertical polarized waves and horizontal polarized waves due to various factors such as reflection. Thus, the built-in antenna for a radio communication terminal according to this embodiment matches the polarization plane of the signal sent from the other end of communication, which makes it possible to increase the reception gain more than Embodiment 60 and Embodiment 61.

[0358] According to this embodiment, loop antenna 621 is mounted in such a way that this loop plane is quasi-perpendicular to the human body and the loop plane above is quasi-parallel to the upper surface and the side of the radio communication terminal, which makes it possible not only to suppress deterioration of gain caused by influences from the human body but also to receive both horizontal polarized waves and vertical polarized waves, thus increasing the gain. This makes it possible to prevent deterioration of gain due to mismatch with the polarization plane of the signal from the other end of communication and provide a high gain built-in antenna for a radio communication terminal with little influence from the human body.

(Embodiment 63)

[0359] Embodiment 63 to Embodiment 67 are modes in which the above-described loop antenna is provided with various means for changing impedance in order to reduce the size or broaden the band of the loop antenna in Embodiment 60 to Embodiment 62.

[0360] Embodiment 63 is a mode in which a reactance element is used as one of impedance changing means to reduce the size or broaden the band of the loop antenna. The built-in antenna for a radio communication terminal according to Embodiment 63 will be explained using FIG. 75A and FIG. 75B.

[0361] FIG.75A is a schematic diagram showing a configuration of a first built-in antenna for a radio communication terminal according to Embodiment 63. In FIG.75A, reactance element 632 is provided at a midpoint facing the power supply terminals of loop antenna element 631.

[0362] FIG.75B is a schematic diagram showing a configuration of a second built-in antenna for a radio communication terminal according to Embodiment 63. In FIG.75B, reactance element 632 is provided at a midpoint of two sides, which are perpendicular to the power supply terminals of loop antenna element 631.

[0363] Providing reactance element 632 at a midpoint of each side making up the loop plane of loop antenna element 631 changes current distribution of loop antenna element 631, making it possible to change impedance of the power supply terminals of loop antenna element 631. Even if loop antenna element 631 is reduced in size, this allows reactance element 632 to change impedance and thereby achieve an impedance characteristic similar to a large loop antenna. Therefore, providing reactance element 632 makes it possible to reduce the size of the loop antenna.

[0364] Moreover, by changing the position at which reactance element 632 is placed in loop antenna element 631 or changing the magnitude of reactance of reactance element 632, it is possible to change impedance of the power supply terminals, emission pattern and resonance condition. Thus, by changing the mounting condition of reactance element 632, it is possible to widen the frequency band of the loop antenna.

[0365] Thus, by providing the loop antenna element with a reactance element, this embodiment allows the impedance characteristic of the loop antenna element to be changed. Thus, it is possible to provide a small and wideband built-in antenna for a radio communication terminal.

(Embodiment 64)

[0366] Embodiment 64 is a mode in which a variable capacitive element is used as one of impedance changing means to reduce the size and broaden the band of the loop antenna. The built-in antenna for a radio communication terminal according to Embodiment 64 will be explained using FIG.76.

[0367] FIG.76 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 5. In FIG.76, variable capacitive element 642 is provided at the power supply terminals of loop antenna element 641.

[0368] For the loop antenna when the size of the loop antenna element is reduced and the circumference is set to quasi-half wavelength or below, the reactance component of impedance of this loop antenna is inductive. Thus, this embodiment makes it possible to achieve impedance matching of the loop antenna above by providing variable capacitive element 642 at the power supply terminals of the loop antenna element 641. That is, when the size of loop antenna element 641 is reduced, it is possible to achieve impedance matching for a wide range of frequencies by changing the capacitance of variable capacitive element 642.

[0369] Thus, since variable capacitive element 642 is provided at the power supply terminals of the loop antenna element 641, this embodiment allows flexible impedance matching by changing the capacitance of variable capacitive element 642. Therefore, this embodiment can provide a small and wideband built-in antenna for a radio communication terminal.

(Embodiment 65)

[0370] Embodiment 65 is a mode in which a tuning element and switching element are used as one of impedance changing means to reduce the size and broaden the band of the loop antenna. The built-in antenna for a radio communication terminal according to Embodiment 65 will be explained using FIG.77.

[0371] FIG.77 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 6. In FIG.77, a circuit with a pair or a plurality of pairs of serially connected tuning element 652 and switching element 653 aligned in parallel is inserted at the power supply terminals of loop antenna element 651.

[0372] In the built-in antenna for a radio communication terminal in the above configuration, when all switching elements 653 are opened, the loop antenna can be used at the original tuning frequency. On the other hand, when one switching element 653 is closed, this means that tuning element 652 connected to this switching element 653 is inserted in parallel, and therefore the loop antenna tunes a frequency different from the original tuning frequency. Likewise, when a plurality of switching elements 653 is closed, this means that tuning element 652 connected to these switching elements 653 is inserted in parallel, and therefore the loop antenna tunes a frequency according to total connected tuning elements 652.

[0373] As shown above, the built-in antenna for a radio communication terminal in the above configuration can change the frequency band through switching operation of each switching element 653 and can thereby provide tuning according to various frequency bands. Thus, even if the size of the loop antenna is reduced, this embodiment can broaden the frequency band.

[0374] As shown above, through switching operation of a plurality of switching elements inserted in loop antenna element 651, this embodiment can thereby switch between frequency bands and provide a small and wideband built-in antenna for a radio communication terminal.

(Embodiment 66)

[0375] Embodiment 66 is a mode in which the shape of a loop antenna element is changed to reduce the size of the loop antenna. The built-in antenna for a radio communication terminal according to Embodiment 66 will be explained using FIG.78.

[0376] FIG.78 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 66. In FIG.78, part or the whole of loop antenna element 661 is zigzag-shaped. This makes the frequency band of the built-in antenna for a radio communication terminal in the above configuration flexibly changeable, which makes this antenna equivalent to a small antenna.

[0377] As shown above, according to this embodiment, part or the whole of the loop antenna element is zigzag-shaped and this embodiment can thereby provide a small-sized antenna.

(Embodiment 67)

[0378] Embodiment 67 is a mode in which the shape of a loop antenna element is changed to broaden the frequency band of the loop antenna. The built-in antenna for a radio communication terminal according to Embodiment 67 will be explained using FIG.79.

[0379] FIG.79 is a schematic diagram showing a configuration of a built-in antenna for a radio communication terminal according to Embodiment 67. In FIG.79, part or the whole of loop antenna element 671 is tabular-shaped. A tabular-shaped antenna has smaller impedance variations with frequency than a linear antenna element, and therefore its frequency band is wider. Thus, the built-in antenna for a radio communication terminal in the above configuration can realize a wider frequency band.

[0380] Thus, since part or the whole of the loop antenna element is tabular-shaped, this embodiment can implement a wideband antenna.

(Embodiment 68)

[0381] Embodiment 68 to Embodiment 70 are modes in which a diversity antenna is implemented using the built-in antenna for a radio communication terminal in Embodiment 60 to Embodiment 62.

[0382] Embodiment 68 is a mode in which a diversity antenna is implemented using the built-in antenna for a radio communication terminal in Embodiment 1. The built-in antenna for a radio communication terminal according to this embodiment will be explained using FIG.80. Configurations similar to those in Embodiment 60 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0383] FIG.80 is a schematic diagram showing a configuration of a diversity antenna for a radio communication terminal according to Embodiment 68. In FIG. 80, monopole antenna 681 is provided for the built-in antenna for a radio communication terminal in Embodiment 60.

[0384] Here, suppose one antenna making up the diversity antenna is loop antenna 601 in Embodiment 60 and used for reception only. Also suppose the other antenna making up the diversity antenna is monopole antenna 681 and used for both transmission and reception.

[0385] In the diversity antenna for a radio communication terminal in the above configuration, only monopole antenna 681 operates during transmission and loop antenna 601 and monopole antenna 681 operate during reception to carry out diversity reception.

[0386] Thus, according to this embodiment, loop antenna 601 in Embodiment 60 is used as the diversity antenna, which makes it possible to provide a high gain diversity antenna for a radio communication terminal with little influence from the human body.

(Embodiment 69)

[0387] Embodiment 69 is a mode in which a diversity antenna is implemented using the built-in antenna for a radio communication terminal in Embodiment 2 and the monopole antenna in Embodiment 68. The diversity antenna for a radio communication terminal according to this embodiment will be explained using FIG.81. The same configurations as those in Embodiment 61 and Embodiment 68 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0388] FIG.81 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 69. In FIG. 81, monopole antenna 681 is provided for the built-in antenna for a radio communication terminal in Embodiment 61.

[0389] Here, suppose one antenna making up the diversity antenna is loop antenna 611 in Embodiment 61 and used for reception only. Also suppose the other antenna making up the diversity antenna is monopole antenna 681 in Embodiment 68 and used for both transmission and reception.

[0390] In the diversity antenna for a radio communication terminal in the above configuration, only monopole antenna 681 operates during transmission and loop antenna 611 and monopole antenna 681 operate during reception to carry out diversity reception.

[0391] Thus, according to this embodiment, loop antenna 611 in Embodiment 2 is used as the diversity antenna, which makes it possible to prevent deterioration of gain due to mismatch with the polarization plane of the signal from the other end of communication and provide a high gain diversity antenna for a radio communication terminal with little influence from the human body.

(Embodiment 70)

[0392] Embodiment 70 is a mode in which a diversity antenna is implemented using the built-in antenna for a radio communication terminal in Embodiment 62 and the monopole antenna in Embodiment 68. The diversity antenna for a radio communication terminal according to this embodiment will be explained using FIG. 82. The same configurations as those in Embodiment 62 and Embodiment 68 will be assigned the same reference numerals and detailed explanations thereof will be omitted.

[0393] FIG.82 is a schematic diagram showing a configuration of the diversity antenna for a radio communication terminal according to Embodiment 70. In FIG.82, monopole antenna 681 is provided for the built-in antenna for a radio communication terminal in Embodiment 621.

[0394] Here, suppose one antenna making up the diversity antenna is loop antenna 621 in Embodiment 62 and used for reception only. Also suppose the other antenna making up the diversity antenna is monopole antenna 681 in Embodiment 68 and used for both transmission and reception.

[0395] In the diversity antenna for a radio communication terminal in the above configuration, only monopole antenna 681 operates during transmission and loop antenna 621 and monopole antenna 681 operate during reception to carry out diversity reception.

[0396] Thus, according to this embodiment, loop antenna 621 in Embodiment 62 is used as the diversity antenna, which makes it possible to prevent deterioration of gain due to mismatch with the polarization plane of the signal from the other end of communication and provide a high gain diversity antenna for a radio communication terminal with little influence from the human body.

[0397] By the way, the embodiment above describes the case where the base plate, loop antenna and the distance of the loop antenna from the human body and frequency are set as described above, but the present invention is not limited to this and can be modified as appropriate.

[0398] As describe above, the present invention is provided with an antenna element in such a way that the loop plane of the antenna element is quasi-perpendicular to the human body and the circumference of the antenna element is equal to or shorter than quasi-one wavelength of the reception wave and impedance matching is implemented between the antenna element and power supply means appropriately, and the present invention can thereby provide a high gain built-in antenna for a radio communication terminal with little influence from the human body.

[0399] This application is based on the Japanese Patent Application No.HEI 10-370318 filed on December 25, 1998, the Japanese Patent Application No.HEI 11-368284 filed on December 24, 1999, the Japanese Patent Application No. 2000-056476 filed on March 1, 2000 and the Japanese Patent Application No. 2000-118692 filed on April 19, 2000, entire content of which is expressly incorporated by reference herein.

Industrial Applicability

[0400] The present invention is ideally applicable to the field of antennas used for radio equipment and portable terminal, etc., and the field of built-in antennas in particular.

Claims

1. A built-in antenna for a radio communication terminal comprising:

a grounded conductor that is built in a package of a radio communication terminal and forms a tabular plane;

a dipole antenna provided with antenna elements connected to said grounded conductor; and

balanced/unbalanced converting means for matching impedance between said dipole antenna and said grounded conductor and converting a balanced signal to unbalanced signal or vice versa.

2. A diversity antenna provided with two built-in antennas for a radio communication terminal, said built-in antennas for a radio communication terminal being built in a package of the radio communication terminal, comprising:

a grounded conductor that forms a tabular plane;

a dipole antenna provided with antenna elements connected to said grounded conductor; and

balanced/unbalanced converting means for matching impedance between said dipole antenna and said grounded conductor and converting a balanced signal to unbalanced signal or vice versa.

3. The built-in antenna for a radio communication terminal according to claim 1, comprising a bar-shaped passive element, wherein said passive element is provided in such a way that the axial direction is quasi-parallel to the axial direction of the bar-shaped antenna element making up the dipole antenna, a reference plane including the own element and the antenna elements making up said dipole antenna is provided quasi-perpendicular to the main plane of the radio communication terminal and forms directivity in the direction along said reference plane and perpendicular to the main plane of said radio communication terminal.

4. A diversity antenna that comprises a built-in antenna for a radio communication terminal and a bar-shaped monopole antenna and carries out diversity transmission/reception using said built-in antenna for a radio communication terminal and said monopole antenna, wherein said built-in antenna for a radio communication terminal is built in a package of the radio communication terminal and comprises:

a grounded conductor that forms a tabular plane;

a dipole antenna provided with antenna elements connected to said grounded conductor;

balanced/unbalanced converting means for matching impedance between said dipole antenna and said grounded conductor and converting a balanced signal to unbalanced signal or vice versa; and

a bar-shaped passive element, and

said passive element is provided in such a way that the axial direction is quasi-parallel to the axial direction of the bar-shaped antenna element making up the dipole antenna, a reference plane including the own element and the antenna element making up said dipole antenna is provided quasi-perpendicular to the main plane of the radio communication terminal and forms directivity in the direction along said reference plane and perpendicular to the main plane of said radio communication terminal.

5. A built-in antenna for a radio communication terminal comprising:

a grounded conductor that forms a tabular plane;

an antenna element whose one end is connected to said grounded conductor, whose other end is connected to power supply means, whose loop plane formed is provided quasi-perpendicular to the tabular-shaped plane of said grounded conductor, and whose circumference is equal to or shorter than quasi-one wavelength of the reception wave; and

balanced/unbalanced converting means for matching impedance between the other end of said antenna element and said power supply means and converting a balanced signal to unbalanced signal or vice versa.

6. The built-in antenna for a radio communication terminal according to claim 1, wherein the antenna element comprises impedance changingmeans for changing impedance of this antenna element.

7. A built-in antenna for a radio communication terminal comprising:

a grounded conductor that forms a tabular plane;

a dipole antenna connected to said grounded conductor and power supply means; and

balanced/unbalanced converting means for matching impedance between said dipole antenna and said power supply means and converting a balanced signal to unbalanced signal or vice versa.

8. The built-in antenna for a radio communication terminal according to claim 7, wherein the dipole antenna is constructed of two comb-shaped dipole antenna elements placed parallel to each other and is a folded-dipole antenna with impedance connected to the ends of the two antenna elements.

9. A diversity antenna that comprises a built-in antenna for a radio communication terminal and another antenna which is different from said built-in antenna for a radio communication terminal and carries out diversity transmission/reception using said built-in antenna for a radio communication terminal and said different antenna, said built-in antenna for a radio communication terminal comprising:

a grounded conductor that forms a tabular plane;

an antenna element whose one end is connected to said grounded conductor, whose other end is connected to power supply means, whose loop plane formed is provided quasi-perpendicular to the tabular-shaped plane of said grounded conductor, and whose circumference is equal to or shorter than quasi-one wavelength of the reception wave; and

balanced/unbalanced converting means for matching impedance between the other end of said antenna element and said power supply means and converting a balanced signal to unbalanced signal or vice versa.

10. A diversity antenna that comprises a built-in antenna for a radio communication terminal and another antenna which is different from said built-in antenna for a radio communication terminal and carries out diversity transmission/reception using said built-in antenna for a radio communication terminal and said different antenna, said built-in antenna for a radio communication terminal comprising:

a grounded conductor that forms a tabular plane;

a dipole antenna connected to said grounded conductor and power supply means; and

balanced/unbalanced converting means for matching impedance between said dipole antenna and said power supply means and converting a balanced signal to unbalanced signal or vice versa.

11. A radio communication terminal apparatus comprising a built-in antenna for a radio communication terminal, said built-in antenna for a radio communication terminal comprising:

a grounded conductor that is built in a package of a radio communication terminal and forms a tabular plane;

a dipole antenna provided with antenna elements connected to said grounded conductor; and

balanced/unbalanced converting means for matching impedance between said dipole antenna and said grounded conductor and converting a balanced signal to unbalanced signal or vice versa.

12. A base station apparatus comprising a built-in antenna for a radio communication terminal, said built-in antenna for a radio communication terminal comprising:

a grounded conductor that is built in a package of a radio communication terminal and forms a tabular plane;

a dipole antenna provided with antenna elements connected to said grounded conductor; and

balanced/unbalanced converting means for matching impedance between said dipole antenna and said grounded conductor and converting a balanced signal to unbalanced signal or vice versa.

Drawing