WINDOW-GLASS ANTENNA FOR VEHICLE

Abstract

 An antenna includes core-wire-side and ground-side feeding points aligned close to each other on a glass surface of a window of the vehicle near an opening of a metallic flange of the window; a ground-side element including a line extending from the ground-side feeding point in a direction away from a portion of the metallic flange which is located closest to the ground-side feeding point; and a core-wire-side element including a core-wire-side first line extending from the core-wire-side feeding point substantially in parallel with the line of the ground-side element, and a core-wire-side second line extending from the core-wire-side first line in a branched manner or extending directly from the core-wire-side feeding point in parallel with the core-wire-side first line. A length from the core-wire-side feeding point to a tip of the core-wire-side first line and a length from the core-wire-side feeding point to a tip of the core-wire-side second line correspond to two separate resonance frequencies within the frequency bandwidth to cause a resonance at each of the two separate resonance frequencies.

Description

TECHNICAL FIELD

[0001] The present invention relates to an antenna adapted to receive a frequency band of Band III of DAB standard (DAB: Digital Audio Broadcasting) for digital terrestrial radiobroadcast waves, more particularly, relates to an ungrounded-type antenna which is provided to a front window glass, a rear window glass and/or a side non-opening fixed window glass of a vehicle.

BACKGROUND OF THE INVENTION

[0002] Recently, digital radios having various types of digital-modulation methods have been developed which produce lower noise and higher quality than AM/FM radio broadcasting using a conventional analog-modulation method. In many countries of the world, digital radio broadcastings are reaching a practical use under various broadcasting standards of DAB (Digital Audio Broadcasting), DRM (Digital Radio Mondiale), DMB (Digital Multimedia Broadcasting), ISDB (Integrated Services Digital Broadcasting) and the like.

[0003] Among these various types of standards for digital radio broadcasting, most countries of the world except the United States and Japan adopt the DAB standard as a global standard. In the DAB standard, two separate frequency bands of the Band III ranging from 174 to 240 MHz and an L-Band ranging from 1452 to 1492 MHz are mainly used so that every country adopts either of the Band III and the L-Band.

[0004] If an antenna is designed to obtain a resonance at a certain frequency existing within a relatively-high frequency band as in the case of L-Band of DAB standard, a high receiving sensitivity can be attained over a wide frequency range around this resonance frequency.

[0005] On the other hand, if an antenna is designed to obtain a resonance at a certain frequency existing within a relatively-low frequency band as in the case of Band III of DAB standard, the high receiving sensitivity tends to be attained only in a narrow frequency range around this resonance frequency.

[0006] That is, the Band III ranging from 174 to 240 MHz has a wide bandwidth equal to 66 MHz. In the case that only one resonance frequency exists within the frequency band of Band III, there is a problem that a favorable receiving sensitivity cannot be obtained over whole of the frequency band (at all frequencies) of Band III because a frequency range over which resonance can occur is narrow. Hence, various antennas devised to improve this problem are being developed.

[0007] Japanese Patent Application Publication No. 7-46016 discloses a glass antenna for an automobile telephone. In this technique, a hot-side antenna line is provided on a window glass and extended in the horizontal direction so as to be electromagnetically coupled with an upper or lower horizontal edge of a metallic window frame of vehicle body to which the window glass is attached. On the other hand, an earth-side antenna line is located in an inner (central) portion of the window glass beyond the hot-side antenna line. One end of the earth-side antenna line is located near one end or a center of the hot-side antenna line. (see Patent Literature 1)

[0008] Japanese Patent Application Publication No. 2000-295023 discloses a film antenna for digital audio broadcast. In this technique, the antenna includes a resin film, a composite antenna element constituted by strip-shaped thin-film conductors formed on a surface of the resin film, and an electrically-feeding cable connected with an electrically-feeding point of the composite antenna element. The composite antenna element includes a first antenna element configured to be applicable to a first frequency band, and a second antenna element provided adjacent to the first antenna element and configured to be applicable to a second frequency band that is lower in frequency level than the first frequency band. The second antenna element is bent at its portion which is a zero-level point of current distribution that is caused on the second antenna element on the basis of electromagnetic wave of the first frequency band. (see Patent Literature 2)

[0009] Moreover, Japanese Patent Application Publication No. 2001-127519 discloses a side-window glass antenna for an automobile. In this technique, an antenna conductor, an earth conductor, an electrically-feeding point of the antenna conductor, and an earth point of the earth conductor are provided to a side-window glass plate of the automobile. These feeding point and earth point are located near a right edge portion of the side-window glass plate as viewed from an interior side or exterior side of the automobile. The earth point is disposed substantially above the feeding point. The antenna conductor extends from the feeding point in a clockwise direction along an outer circumferential edge of the side-window glass plate in a manner that the antenna conductor almost circulates in the side-window glass plate to surround the earth conductor. The earth conductor includes an upper earth element and a lower earth element. The upper earth element extends from the earth point or a connecting earth element attached to the earth point in a substantially left direction. The lower earth element extends from the earth point or the connecting earth element in the clockwise direction. (see Patent Literature 3)

[0010] Furthermore, Japanese Patent Application Publication No. 2009-49706 discloses a glass antenna for a vehicle. In this technique, the antenna for receiving a broadcast wave for the digital terrestrial television is provided to a corner portion of a window glass of a side portion of the vehicle that is located on a rear-seat side. This antenna includes two positive and negative (power-)feeding points provided to the corner portion of the side window glass, a first element, and a second element. The first element includes a first vertical line which extends vertically toward a corner and which is at least one of at least two lines extending from the positive feeding point, and a first horizontal line extending horizontally from a tip of the first vertical line or from an intermediate portion of the first vertical line in a branched manner. The second element includes at least two second horizontal lines extending horizontally from the negative feeding point, and a second vertical line extending vertically from the negative feeding point. The positive and negative feeding points are connected respectively with a core wire and an enveloping conductor wire of a coaxial cable. (see Patent Literature 4)

CITATION LIST

Patent Literature

[0011] 

Patent Literature 1 : Japanese Patent Application Publication No. 7-46016

Patent Literature 2 : Japanese Patent Application Publication No. 2000-295023

Patent Literature 3 : Japanese Patent Application Publication No. 2001-127519

Patent Literature 4 : Japanese Patent Application Publication No. 2009-49706

SUMMARY OF THE INVENTION

[0012] The invention of the above Patent Literature 1 relates to a window glass antenna for automobile telephone operating in a frequency range from 810 MHz to 960 MHz, but not relates to an antenna for digital terrestrial radiobroadcast waves under the DAB standard. In the invention of the above Patent Literature 1, the ungrounded-type antenna is constituted by the hot-side antenna line and the earth-side antenna line. This hot-side antenna line is electromagnetically coupled with the horizontal edge of the metallic window frame. However, if trying to use this window glass antenna for automobile telephone as an antenna for the Band III of DAB standard, a problem is caused that a high reception gain cannot be attained over the entire range of the Band III of DAB standard because the number of hot-side antenna lines which is effective for broadening a receivable bandwidth is one in this case.

[0013] In the technique of the above Patent Literature 2, an antenna pattern is formed in order to receive digital radiobroadcast waves in both of the Band III and the L-Band of the standard by enabling resonances in both of the Band III and the L-Band. However, in the technique of the above Patent Literature 2, a high gain of the receiving sensitivity is not obtained over the entire frequency band of wider one of the Band III and the L-Band. Also, there is a problem that the antenna is susceptible to an influence of noises from a defogger or metallic body because no earth-side element is provided.

[0014] In the technique of the above Patent Literature 3, the window glass antenna is formed to receive FM radiobroadcast waves ranging from 76 MHz to 90 MHz, but is not formed to receive the digital terrestrial radiobroadcast waves within the L-Band or the Band III having a wide frequency range. This antenna is constituted by one antenna conductor provided to surround the earth conductor. If trying to use this antenna as an antenna for receiving the digital terrestrial radiobroadcast waves of the Band III of DAB standard, there is a problem that a high reception gain cannot be obtained over the entire frequency band of Band III.

[0015] The antenna of the above Patent Literature 4 is not an antenna formed to receive the digital terrestrial radiobroadcast waves of the DAB standard, but is an ungrounded-type window glass antenna formed to receive digital terrestrial broadcast waves ranging from 470 to 710 MHz. An antenna pattern of this technique is provided along an inside of vertical edge of a metallic flange. The core-wire-side element (first element) of the antenna includes at least two lines extending from the positive feeding point. At least one of the at least two lines extends in the vertical direction toward the corner and then extends in the horizontal direction from a tip of this vertically-extending portion or from an intermediate point of this vertically-extending portion in a branched manner. When the antenna of this technique is used for digital terrestrial television, the receiving characteristic has no problem. However, when the antenna of this technique is used as an antenna for digital terrestrial radiobroadcast in the Band III or L-Band of DAB standard, there is a problem that the antenna becomes susceptible to the influence of metallic body to reduce the receiving characteristic because the core-wire-side element is in proximity to the metallic flange.

[0016] It is therefore an object of the present invention to attain a satisfactory receiving sensitivity over an entire frequency band of the Band III ranging from 174 to 240 MHz or the L-Band ranging from 1452 to 1492 MHz when receiving digital radiobroadcast of the DAB standard.

[0017] According to one aspect of the present invention, there is provided a glass antenna for a vehicle, the glass antenna being of ungrounded-type and being configured to receive airwaves over an entire frequency bandwidth of a Band III of DAB standard for digital terrestrial radiobroadcast waves, the antenna comprising: core-wire-side and ground-side feeding points aligned close to each other on a glass surface of a window of the vehicle near an opening of a metallic flange of the window; a ground-side element including a line extending from the ground-side feeding point in a direction away from a portion of the metallic flange which is located closest to the ground-side feeding point; and a core-wire-side element including a core-wire-side first line extending from the core-wire-side feeding point substantially in parallel with the line of the ground-side element, and a core-wire-side second line extending from the core-wire-side first line in a branched manner or extending directly from the core-wire-side feeding point in parallel with the core-wire-side first line, wherein a length from the core-wire-side feeding point to a tip of the core-wire-side first line and a length from the core-wire-side feeding point to a tip of the core-wire-side second line correspond to two separate resonance frequencies within the frequency bandwidth to cause a resonance at each of the two separate resonance frequencies.

BRIEF EXPLANATION OF DRAWINGS

[0018] 

[FIG. 1] An enlarged front view of an antenna pattern in a first example according to the present invention.

[FIG. 2] An enlarged front view of an antenna pattern in a second example according to the present invention.

[FIG. 3] An enlarged front view of an antenna pattern in a third example according to the present invention.

[FIG. 4] An enlarged front view of an antenna pattern in a fourth example according to the present invention.

[FIG. 5] An enlarged front view of an antenna pattern in a fifth example according to the present invention.

[FIG. 6] An enlarged front view of an antenna pattern in a sixth example according to the present invention.

[FIG. 7] An enlarged front view of an antenna pattern in a seventh example according to the present invention.

[FIG. 8] A view showing a case that the antenna pattern of the first example is provided to a front window glass of automobile.

[FIG. 9] A view showing a case that the antenna pattern of the first example is provided to the front window glass of automobile.

[FIG. 10] A view showing a case that the antenna pattern of the first example is provided to a rear window glass of automobile.

[FIG. 11] An enlarged front view of an antenna pattern in a first comparative example.

[FIG. 12] A frequency characteristic view in Band III of DAB standard which was obtained by the first example according to the present invention and the first comparative example.

[FIG. 13] An enlarged front view of the antenna pattern in an eighth example according to the present invention.

[FIG. 14] A view showing a case that the antenna pattern of the eighth example is provided to the front window glass of automobile.

[FIG. 15] A frequency characteristic view in the Band III of DAB standard which was obtained by the eighth example according to the present invention and the first comparative example.

DETAILED DESCRIPTION OF INVENTION

[0019] According to the present invention, an ungrounded-type (floating) glass antenna for receiving digital terrestrial radiobroadcast waves under a DAB standard includes a core-wire-side element 10 extending from a core-wire-side electrically-feeding point 6 and a ground-side element 20 extending from a ground-side electrically-feeding point 7.

[0020] The core-wire-side feeding point 6 and the ground-side feeding point 7 are provided on a glass surface adjacent to each other in a row arrangement, along an opening edge of a metallic flange 3 for a window of automobile (vehicle). A distance between the core-wire-side feeding point 6 and (that opening edge of) the metallic flange 3 is substantially equal to a distance between the ground-side feeding point 7 and (that opening edge of) the metallic flange 3. The core-wire-side element 10 extends from the core-wire-side feeding point 6 in a direction away from the opening edge of the metallic flange 3 which is closest to the core-wire-side feeding point 6, i.e., in a direction toward a substantially-central portion of a plate of the glass. Similarly, the ground-side element 20 extends from the ground-side feeding point 7 in the direction away from the opening edge of the metallic flange 3 which is closest to the ground-side feeding point 7, i.e., in the direction toward the substantially-central portion of the glass plate. The core-wire-side element 10 and the ground-side element 20 extend parallel to each other.

[0021] Although the core-wire-side element 10 and the ground-side element 20 extend parallel to each other respectively from the core-wire-side feeding point 6 and the ground-side feeding point 7 in shown embodiments, the core-wire-side element 10 and/or the ground-side element 20 may be bent at any spot thereof in such a manner that the core-wire-side element 10 does not intersect with the ground-side element 20.

<Arrangement around Upper edge of Metallic flange>

[0022] In a case that an antenna according to the present invention is arranged at a location around (near) an upper or lower edge of the opening of the metallic flange 3 except locations near corners of the opening of the metallic flange 3, the core-wire-side element 10 and the ground-side element 20 which are constituted by lines (strips) are provided by extending the lines parallel to each other and in a direction that is perpendicular to the upper or lower edge and that is toward the substantially-central portion of the glass plate. In this case, a location of the core-wire-side element 10 and a location of the ground-side element 20 can be interchanged to right and left.

[0023] In a case that an antenna according to the present invention is arranged at a location around the upper or lower edge of the opening of the metallic flange 3 and near the corner of the opening, the core-wire-side element 10 and the ground-side element 20 which extend in the direction perpendicular to the upper or lower edge (i.e., vertical direction) are disposed such that the ground-side element 20 is located close to the corner of the opening of the metallic flange 3 whereas the core-wire-side element 10 is located away from the corner of the opening of the metallic flange 3. (namely, the ground-side element 20 is located between the core-wire-side element 10 and the corner of the opening)

<Arrangement around Vertical edge of Opening of Metallic flange>

[0024] In a case that an antenna according to the present invention is arranged at a location around (near) a vertically-extending edge (hereinafter, vertical edge) of the opening of the metallic flange 3 except locations near corners of the opening of the metallic flange 3, namely, in a case that the antenna is arranged at an intermediate portion of the vertical edge of the opening; the core-wire-side element 10 and the ground-side element 20 which are constituted by lines (strips) are provided by extending the lines in a horizontal direction toward the substantially-central portion of the glass plate. In this case, a location of the core-wire-side element 10 and a location of the ground-side element 20 can be interchanged to up and down.

[0025] In a case that an antenna according to the present invention is arranged at a location around the vertical edge of the opening of the metallic flange 3 and near the corner of the opening, the core-wire-side element 10 and the ground-side element 20 which extend in the horizontal direction are disposed such that the ground-side element 20 is arranged close to the corner of the opening of the metallic flange 3 whereas the core-wire-side element 10 is arranged away from the corner of the opening of the metallic flange 3. (namely, the ground-side element 20 is located between the core-wire-side element 10 and the corner of the opening with respect to the vertical direction)

[0026] The ground-side element 20 is a ground-side first line (strip) 21 which extends in the direction away from a portion of the metallic flange 3 which is located closest to the ground-side electrically-feeding point 7. The core-wire-side element 10 includes a core-wire-side first line (strip) 11 and a core-wire-side second line (strip) 13. The core-wire-side first line 11 extends from the core-wire-side feeding point 6 substantially parallel to the ground-side element 20. The core-wire-side second line 13 extends through an orthogonal line 12 in parallel with the core-wire-side first line 11 (from end of an orthogonal line 12) to have a clearance between the core-wire-side second line 13 and the core-wire-side first line 11. The orthogonal line 12 extends from the core-wire-side feeding point 6 or an intermediate portion of the core-wire-side first line 11 in a direction perpendicular to the core-wire-side first line 11. A length from the core-wire-side feeding point 6 to a tip (distal end) of the core-wire-side first line 11 is determined according to one of wavelengths of two resonance frequencies which are appropriately distant from each other within a frequency bandwidth of the Band III of DAB standard. A length from the core-wire-side feeding point 6 to a tip of the core-wire-side second line 13 is determined according to another of the wavelengths of the two resonance frequencies.

[0027] Moreover, the core-wire-side first line 11 and the core-wire-side second line 13 of the core-wire-side element 10 are disposed at a location sufficiently away from the metallic flange 3 so as not to be affected by the metallic flange 3. Alternatively, the ground-side element 20 is disposed between the metallic flange 3 and the core-wire-side element 10.

[0028] Thus, at one of the two resonance frequencies within the bandwidth defined by the Band III of DAB standard, a receiving sensitivity is enlarged by a strongest resonance because of the length of the core-wire-side first line. At another of the two resonance frequencies, the receiving sensitivity is enlarged by a strongest resonance because of the length of the core-wire-side second line. That is, the two different lines having lengths which cause resonances at the two separate frequencies (i.e., two frequencies having a sufficient interval therebetween) are provided to the core-wire-side element 10. Accordingly, airwaves can be favorably received over whole of the bandwidth defined by the Band III.

[0029] As explained above, the antenna according to the present invention can favorably receive airwaves within the Band III of DAB standard which is the frequency band ranging from 174 to 240 MHz. Additionally, the antenna according to the present invention can properly receive airwaves within the L-Band of DAB standard which is another frequency band ranging from 1452 to 1492 MHz.

[0030] It is noted that, in the above explanation, the length of the core-wire-side first line denotes a length from the core-wire-side feeding point to the tip of the core-wire-side first line, and the length of the core-wire-side second line denotes a length from the core-wire-side feeding point to the tip of the core-wire-side second line.

[0031] The line length causing resonance is represented by α λ/4, wherein α denotes a wavelength compaction ratio (wavelength shortening ratio) of the glass, and λ denotes a wavelength of resonance frequency.

[0032] Moreover, according to the present invention, the ground-side element is not limited to a straight-line shape. That is, as shown in FIG. 5, the ground-side element may be formed as a rectangular closed-loop line.

[0033] Moreover, as shown in FIG. 6, the core-wire-side element may be formed as an approximately rectangular closed-loop line by connecting a tip-nearby portion of the core-wire-side second line to the core-wire-side first line.

<Arrangement of Antenna according to Present invention on Front window glass of Vehicle>

[0034] In a case that an antenna according to the present invention is arranged on a front window glass of automobile (vehicle) as shown in FIGS. 8 and 9, it is preferable that the antenna is provided at a location near the upper edge of the opening of the metallic flange in order not to obstruct a front visibility of driver. It is more preferable that the antenna is located at the upper edge of the opening of the metallic flange except locations near the corners of the opening.

[0035] As shown in FIG. 8, in the antenna provided at a location near the upper edge of the opening, the core-wire-side element 10 extends from the core-wire-side feeding point 6 in the vertical direction toward the substantially-central portion of the glass plate whereas the ground-side element 20 extends from the ground-side feeding point 7 in the vertical direction toward the substantially-central portion of the glass plate and in parallel with the core-wire-side element 10.

[0036] In this case, each of the core-wire-side element 10 and the ground-side element 20 is extended from the core-wire-side feeding point or the ground-side feeding point in the direction away from a portion of the metallic flange which is closest to the core-wire-side feeding point or the ground-side feeding point. That is, each of the core-wire-side element 10 and the ground-side element 20 extends in the direction toward the central portion of the glass plate. Accordingly, adverse effects by metallic body is reduced.

[0037] In a case that an antenna according to the present invention is arranged at a location near the corner of the opening of the metallic flange 3 as shown in FIG. 9, the ground-side element 20 is disposed at a location closer to the corner, i.e., closer to the vertical edge of the opening, and the core-wire-side element 10 is disposed at a location far from the vertical edge of the opening. Accordingly, harmful effects such as a noise from the metallic body can be blocked by the ground-side element.

[0038] In a case that an antenna according to the present invention is arranged at a location near a center portion of the upper edge of the opening of the metallic flange 3 which is sufficiently apart from the corners of the opening as shown in FIG. 8, any of the core-wire-side element 10 and the ground-side element 20 can be located closer to the vertical edge of the metallic flange because both of the core-wire-side element 10 and the ground-side element 20 keep sufficiently apart from the vertical edge.

[0039] Moreover, in a case that each of the core-wire-side element 10 and the ground-side element 20 is bent at arbitrary spot thereof in a manner that the core-wire-side element 10 and the ground-side element 20 do not intersect with each other as shown in FIG. 14, a sight range of the driver can be secured more largely than the case that the core-wire-side element 10 and the ground-side element 20 extend straightly in parallel with each other. Therefore, this case is a more preferable embodiment.

<Arrangement of Antenna according to Present invention on Rear window glass of Vehicle>

[0040] Furthermore, in a case that an antenna according to the present invention is arranged on a rear window glass of automobile (vehicle) as shown in FIG. 10, the antenna is compelled to be located near four corners of the opening of the metallic flange 3 in many cases. This is because, in many cases, a defogger 4 is provided to the rear window glass, and another antenna (not shown) is provided to a center portion of an upper or lower blank space of the defogger 4 (i.e., blank space above or below the defogger 4). If each element of the antenna according to the present invention is disposed in the vertical direction, there is a risk that the antenna interferes with the defogger 4 in dependence upon the length of the element of the antenna. Hence, it is preferable that the each element 20, 30 of the antenna according to the present invention is disposed in the horizontal direction (parallel to the defogger 4).

[0041] Accordingly, in this case, near one of the four corners of the opening of the metallic flange 3, the ground-side feeding point and the core-wire-side feeding point are arranged at the vertical edge except the corner in this order from a side of the corner. Then, the respective lines of the ground-side element 20 and the core-wire-side element 10 are extended in the horizontal direction away from the vertical edge of the flange.

[0042] As mentioned above, the ground-side feeding point 7 and the core-wire-side feeding point 6 are aligned in this order from the location of the corner, and the ground-side element 20 and the core-wire-side element 10 are formed to extend respectively from the ground-side feeding point 7 and the core-wire-side feeding point 6 in the horizontal direction. Thereby, the core-wire-side element 10 is kept far away from a horizontally-extending edge (hereinafter, horizontal edge) of the metallic flange 3. Accordingly, the adverse effects such as a noise from the metallic flange 3 can be blocked by the ground-side element 20.

[0043] Moreover, as mentioned above, each of the ground-side element 20 and the core-wire-side element 10 is extended in the horizontal direction away from a portion of the vertical edge of the metallic flange which is closest to the ground-side feeding point or the core-wire-side feeding point. That is, each of the ground-side element 20 and the core-wire-side element 10 is extended in a direction toward the central portion of the glass plate. This is in order to reduce the adverse effects such as noises caused by the metallic body.

<Arrangement of Antenna according to Present invention on Side window glass of Vehicle>

[0044] In a case that an antenna according to the present invention is arranged on a side window glass of automobile (vehicle), the core-wire-side feeding point and the ground-side feeding point can be aligned side by side along any of all opening edges of a metallic flange of a non-opening window (fixed-sash-type window) which constitutes the side window of the vehicle. Also in this case, the core-wire-side feeding point and the ground-side feeding point are not provided at corners of the metallic flange of the non-opening window.

[0045] In a case that (feeding points of) an antenna according to the present invention is arranged along an upper or lower edge of the opening of the metallic flange 3 except locations near corners of the opening of the metallic flange 3, the core-wire-side element 10 and the ground-side element 20 extend respectively from the core-wire-side feeding point 6 and the ground-side feeding point 7 substantially parallel to each other and in a direction that is perpendicular to the upper or lower edge and that is toward the substantially-central portion of the glass plate.

[0046] Moreover, in a case that an antenna according to the present invention is arranged along the vertical edge of the opening of the metallic flange 3 except locations near corners of the opening of the metallic flange 3, the core-wire-side element 10 and the ground-side element 20 are extended respectively from the core-wire-side feeding point 6 and the ground-side feeding point 7 substantially parallel to each other and in the substantially-horizontal direction toward the substantially-central portion of the glass plate.

[0047] Furthermore, in a case that an antenna according to the present invention is arranged along the upper or lower edge of the opening of the metallic flange 3 and near the corner of the opening, the ground-side element 20 is disposed at a side closer to the vertical edge of the opening of the metallic flange 3, i.e., closer to the corner whereas the core-wire-side element 10 is disposed at a side away from the vertical edge of the opening. Accordingly, the harmful effects from the metallic body can be blocked by the ground-side element.

[0048] Similarly, in a case that an antenna according to the present invention is arranged along the vertical edge of the opening of the metallic flange 3 and near the corner of the opening, the ground-side element 20 is horizontally arranged at a side closer to the horizontal edge of the opening of the metallic flange 3 (except the corner), i.e., closer to the corner whereas the core-wire-side element 10 is disposed at a side away from the horizontal edge. Accordingly, the harmful effects from the metallic body can be blocked by the ground-side element.

[0049] Each of the lines of the core-wire-side element 10 and the ground-side element 20 has a width ranging from 0.3 to 0.8 mm, approximately.

[0050] The core-wire-side feeding point 6 of the antenna for receiving the digital terrestrial radiobroadcast waves is connected to a core conductor of a coaxial cable. The ground-side feeding point is connected to an enveloping conductor of the coaxial cable.

[0051] Such a glass antenna for the digital terrestrial radiobroadcast is provided at a location near the upper edge of the opening of the metallic flange of the front window of vehicle except at a location near the corners, as shown in FIG. 8. Alternatively, as shown in FIG. 9, the glass antenna is provided at a location around the upper edge of the opening of the metallic flange of the front window of vehicle and near the corner. Alternatively, as shown in FIG. 10, the glass antenna is provided at a location around the vertical or horizontal edge of the metallic flange of the rear window glass and near the corner. Alternatively, although not shown, the glass antenna is provided at a location around the upper, lower or vertical edge of the metallic flange of the non-opening fixed window which constitutes the side window of vehicle, except the corner portion of the metallic flange. In any case, the glass antenna according to the present invention can obtain a good reception gain, even used solely.

[0052] In a case that a diversity reception is performed by providing antennas according to the present invention at a plurality of locations of some of the window glasses or by combining the antenna according to the present invention with another type of antenna for receiving the digital terrestrial radiobroadcast waves, the reception gain can be enhanced even when receiving airwaves coming from a side (right-left) direction of the vehicle so that a directivity can be enhanced.

[0053] In a case that an insulating ceramic-paste layer 2 colored in black or the like is printed on a peripheral portion (edge-surrounding portion) of the window glass 1 for the automobile (vehicle), it is preferable that the core-wire-side feeding point 6 and the ground-side feeding point 7 of the antenna for the digital terrestrial radio are overlaid upon the ceramic-paste layer 2 after drying the ceramic-paste layer 2. Accordingly, the respective core-wire-side feeding point 6 and ground-side feeding point 7 of the antenna become invisible from an outside of the vehicle, resulting in an improvement of visual quality.

[0054] Moreover, the above-explained antenna pattern according to the present invention can be produced by printing an electrically-conductive material on a transparent resin film or sheet having an adhesive face or by sticking wire lines and the like on the transparent resin film or sheet. Then, such a produced antenna pattern can be stuck on the surface of the window glass of automobile, a surface of window glass for architectural construction, various types of panels and the like.

[0055] Furthermore, the antenna pattern according to the present invention may be produced by printing an electrically-conductive material on a transparent resin film or sheet having an adhesive face or by sticking wire lines and the like on the transparent resin film or sheet. Then, such a produced antenna pattern may be stuck on the surface of the window glass of automobile.

EXAMPLES

[0056] Examples according to the present invention will now be explained.

[First Example]

[0057] As shown in FIG. 1, within an upper blank space of the defogger 4 (i.e., blank space above the defogger 4) of the rear window glass 1 of automobile (vehicle), an antenna in a first example according to the present invention is arranged on a surface of the rear window glass 1 near the vertical edge of the opening of the metallic flange 3. This antenna is an ungrounded-type (floating) antenna for the digital terrestrial radio which is constituted by two elements of the core-wire-side element 10 and the ground-side element 20.

[0058] The ground-side element 20 includes a ground-side first line 21 extending from an upper edge of the ground-side feeding point 7 in the horizontal direction away from the vertical edge of the opening of the metallic flange 3. The ground-side feeding point 7 is formed in a square shape having horizontal and vertical edges each having a length equal to 12 mm. The ground-side first line 21 has a length equal to 50 mm.

[0059] On the other hand, the core-wire-side element 10 includes the core-wire-side first line 11 and the core-wire-side second line 13. The core-wire-side first line 11 extends from an upper edge of the core-wire-side feeding point 6 in the horizontal direction away from the vertical edge of the opening of the metallic flange 3. The core-wire-side feeding point 6 is formed in a square shape having horizontal and vertical edges each having a length equal to 12 mm. The core-wire-side first line 11 has a length equal to 120 mm. The core-wire-side second line 13 includes the orthogonal line 12 extending from an intermediate portion (some middle-point) of the core-wire-side first line 11 in the vertical direction toward the ground-side element 20. That is, the orthogonal line 12 is disposed orthogonal to the core-wire-side first line 11 in a manner branched from the core-wire-side first line 11. The orthogonal line 12 has a length equal to 25 mm. (A portion of) The core-wire-side second line 13 extends from a tip of the orthogonal line 12 in the same direction as the extending direction of the core-wire-side first line 11. The portion of the core-wire-side second line 13 which extends from the tip of the orthogonal line 12 has a length equal to 25 mm.

[0060] A length (distance) between an end portion of the core-wire-side feeding point 6 and a branch point of the orthogonal line 12 from the core-wire-side first line 11 is equal to 10 mm. An amount of clearance between the core-wire-side feeding point 6 and the ground-side feeding point 7 is equal to 18 mm.

[0061] The respective feeding points and the respective lines of the core-wire-side element 10 and the ground-side element 20 were formed as follows. An electrically-conductive ceramic paste is printed on a predetermined location of an interior-side surface of the window glass plate to cause a width of each line 11, 12, 13 and 21 of the core-wire-side element 10 and the ground-side element 20 to become equal to 0.7 mm. Then, the ceramic paste printed on the window glass plate is dried and burnt in a heating furnace.

[0062] The antenna for receiving the digital terrestrial radiobroadcast waves in the first example which was formed in the above processing was provided to the rear window glass of automobile. Then, the core-wire-side feeding point 6 was connected with a core conductor of a coaxial cable extended from a tuner (not shown) whereas the ground-side feeding point 7 was connected with an enveloping conductor of the coaxial cable. This antenna received the digital terrestrial radiobroadcast waves in the frequency range of the Band III which is ranging from 174 to 240 MHz.

[0063] A frequency characteristic within the frequency range of the Band III is shown in FIG. 12 which was obtained by the pattern of the first example (see FIG. 1) according to the present invention and a pattern of an after-mentioned first comparative example.

[0064] As shown in FIG. 12, it can be found that a reception sensitivity of the pattern of the first example according to the present invention that is shown by a solid line is higher than a reception sensitivity of the pattern of the first comparative example that is shown by a dotted line, over the entire frequency range of the Band III.

[Second Example]

[0065] As shown in FIG. 2, within an upper blank space of the defogger 4 (i.e., blank space above the defogger 4) of the rear window glass 1 of automobile (vehicle), an antenna pattern in a second example according to the present invention is arranged on a surface of the rear window glass 1 near the vertical edge of the opening of the metallic flange 3. In the antenna pattern according to the second example, the second line of the core-wire-side element 10 is extended directly from the core-wire-side feeding point 6 in the vertical direction (i.e., direction perpendicular to the core-wire-side first line 11), as is different from the antenna pattern shown in FIG. 1 according to the first example. Moreover, the respective lengths of the orthogonal line 12 and the horizontally-extending portion of the core-wire-side second line 13 of the core-wire-side element 10 in the second example are different from those in the first example. However, the total length from the core-wire-side feeding point 6 to the tip of the core-wire-side second line in the second example is equal to 60 mm, and is substantially equal to that of the first example.

[0066] The length of the core-wire-side first line 11 and the length of the ground-side element 20 in the second example are equal to those of the first example. Also, the distance between the two feeding points in the second example is equal to that in the first example.

[0067] The antenna according to the second example was formed as follows, in the same manner as the first example. An electrically-conductive ceramic paste is printed on a predetermined location of an interior-side surface of the window glass plate. Then, the ceramic paste printed on the window glass plate is dried and burnt in the heating furnace.

[0068] The antenna for receiving the digital terrestrial radiobroadcast waves in the second example which was formed in the above processing was provided to the rear window glass of automobile. Then, the core-wire-side feeding point 6 was connected with a core conductor of a coaxial cable extended from a tuner (not shown) whereas the ground-side feeding point 7 was connected with an enveloping conductor of the coaxial cable. This antenna received the digital terrestrial radiobroadcast waves in the frequency range of the Band III which is ranging from 174 to 240 MHz. As a result, satisfactory receiving sensitivity was obtained to sufficiently satisfy a practical level, in the same manner as the first example.

[Third Example]

[0069] As shown in FIG. 3, near the upper edge of the opening of the metallic flange of the front window glass of automobile (vehicle), the core-wire-side feeding point 6 and the ground-side feeding point 7 of an antenna in a third example according to the present invention are aligned along the upper edge. Then, the core-wire-side element 10 and the ground-side element 20 are extended respectively from the core-wire-side feeding point 6 and the ground-side feeding point 7 in the vertical direction. This structure is different from the first and second examples in which the core-wire-side element 10 and the ground-side element 20 are extended respectively from the core-wire-side feeding point 6 and the ground-side feeding point 7 in the horizontal direction.

[0070] Moreover, in the third example, the core-wire-side second line of the core-wire-side element 10 extends from the core-wire-side feeding point in the perpendicularly-lower direction. In detail, this core-wire-side second line is extended directly from the core-wire-side feeding point 6 in a left direction (of FIG. 3) away from the vertical edge of the opening of the metallic flange 3, and then, is extended from a tip of the left-directional extension in the extending direction of the core-wire-side first line and in parallel with the core-wire-side first line. This structure is different from the pattern of FIG. 2 according to the second example.

[0071] On the other hand, the ground-side element 20 extending from the ground-side feeding point 7 in a direction away from the metallic flange has a shape same as the pattern according to the second example.

[0072] The antenna according to the third example was formed as follows, in the same manner as the second example. An electrically-conductive ceramic paste is printed on a predetermined location of an interior-side surface of the window glass plate. Then, the ceramic paste printed on the window glass plate is dried and burnt in the heating furnace.

[0073] The antenna for receiving the digital terrestrial radiobroadcast waves in the third example which was formed in the above processing was provided to the front window glass of automobile. Then, the core-wire-side feeding point 6 was connected with a core conductor of a coaxial cable extended from a tuner (not shown) whereas the ground-side feeding point 7 was connected with an enveloping conductor of the coaxial cable. This antenna received the digital terrestrial radiobroadcast waves in the frequency range of the Band III which is ranging from 174 to 240 MHz. As a result, satisfactory receiving sensitivity was obtained to sufficiently satisfy a practical level, in the same manner as the second example.

[Fourth Example]

[0074] As shown in FIG. 4, within an upper blank space of the defogger 4 (i.e., blank space above the defogger 4) of the rear window glass 1 of automobile, an antenna pattern in a fourth example according to the present invention is arranged on a surface of the rear window glass 1 near the vertical edge of the opening of the metallic flange 3. In the antenna pattern according to the fourth example, the second line 13 of the core-wire-side element 10 includes the orthogonal line 12 which extends from an intermediate portion of the core-wire-side first line 11 in a lower direction orthogonal to the core-wire-side first line 11 in a manner branched from the core-wire-side first line 11. The core-wire-side second line 13 further includes a portion extending from a tip of the orthogonal line 12 in parallel with the core-wire-side first line 11. Such a structure is different from the antenna pattern shown in FIG. 1 according to the first example. The other structures of the fourth example are identical with those of the first example.

[0075] The antenna according to the fourth example was formed as follows, in the same manner as the first example. An electrically-conductive ceramic paste is printed on a predetermined location of an interior-side surface of the window glass plate. Then, the ceramic paste printed on the window glass plate is dried and burnt in the heating furnace.

[0076] The antenna for receiving the digital terrestrial radiobroadcast waves in the fourth example which was formed in the above processing was provided to the rear window glass of automobile. Then, the core-wire-side feeding point 6 was connected with a core conductor of a coaxial cable extended from a tuner (not shown) whereas the ground-side feeding point 7 was connected with an enveloping conductor of the coaxial cable. This antenna received the digital terrestrial radiobroadcast waves in the frequency range of the Band III which is ranging from 174 to 240 MHz. As a result, satisfactory receiving sensitivity was obtained to sufficiently satisfy a practical level, in the same manner as the first example.

[Fifth Example]

[0077] As shown in FIG. 5, within an upper blank space of the defogger 4 of the rear window glass 1 of automobile, an antenna pattern in a fifth example according to the present invention is arranged on a surface of the rear window glass 1 at the vertical edge of the opening of the metallic flange 3. In the antenna pattern according to the fifth example, the ground-side element 20 is formed in a closed-loop shape. This structure is different from the antenna pattern shown in FIG. 2 according to the second example. A shape of the core-wire-side element 10 in the fifth example is identical with that in the second example.

[0078] In detail, the ground-side element 20 has two horizontal lines that extend in the horizontal direction respectively from the ground-side feeding point 7 to keep a width of the ground-side feeding point 7. By connecting tips of these two horizontal lines with each other, the ground-side element 20 has a rectangular shape.
The antenna according to the fifth example was formed as follows, in the same manner as the second example. An electrically-conductive ceramic paste is printed on a predetermined location of an interior-side surface of the window glass plate. Then, the ceramic paste printed on the window glass plate is dried and burnt in the heating furnace.

[0079] The antenna for receiving the digital terrestrial radiobroadcast waves in the fifth example which was formed in the above processing was provided to the rear window glass of automobile. Then, the core-wire-side feeding point 6 was connected with a core conductor of a coaxial cable extended from a tuner (not shown) whereas the ground-side feeding point 7 was connected with an enveloping conductor of the coaxial cable. This antenna received the digital terrestrial radiobroadcast waves in the frequency range of the Band III which is ranging from 174 to 240 MHz. As a result, satisfactory receiving sensitivity was obtained to sufficiently satisfy the practical level, in the same manner as the second example.

[Sixth Example]

[0080] As shown in FIG. 6, within an upper blank space of the defogger 4 (i.e., blank space above the defogger 4) of the rear window glass 1 of automobile, an antenna pattern in a sixth example according to the present invention is arranged on a surface of the rear window glass 1 near the vertical edge of the opening of the metallic flange 3. In the antenna pattern according to the sixth example, the second line of the core-wire-side element 10 includes the orthogonal line which extends from an intermediate portion of the first line of the core-wire-side element 10 in a branched manner, and a portion which extends from the tip of the orthogonal line. A tip of this portion of the second line is connected with the first line of the core-wire-side element 10, so that the core-wire-side element 10 includes a rectangular-shaped portion. Such a structure is different from the antenna pattern shown in FIG. 2 according to the second example.

[0081] The length of the core-wire-side first line 11 of the core-wire-side element, the length of the ground-side element 20, and the distance between the two feeding points in the sixth example are respectively same as those in the second example.

[0082] The antenna according to the sixth example was formed as follows, in the same manner as the first example. An electrically-conductive ceramic paste is printed on a predetermined location of an interior-side surface of the window glass plate. Then, the ceramic paste printed on the window glass plate is dried and burnt in the heating furnace.

[0083] The antenna for receiving the digital terrestrial radiobroadcast waves in the sixth example which was formed in the above processing was provided to the rear window glass of automobile. Then, the core-wire-side feeding point 6 was connected with a core conductor of a coaxial cable extended from a tuner (not shown) whereas the ground-side feeding point 7 was connected with an enveloping conductor of the coaxial cable. This antenna received the digital terrestrial radiobroadcast waves in the frequency range of the Band III which is ranging from 174 to 240 MHz. As a result, satisfactory receiving sensitivity was obtained to sufficiently satisfy the practical level, in the same manner as the second example.

[Seventh Example]

[0084] As shown in FIG. 7, within an upper blank space of the defogger 4 (i.e., blank space above the defogger 4) of the rear window glass 1 of automobile, an antenna pattern in a seventh example according to the present invention is arranged on a surface of the rear window glass 1 near the vertical edge of the opening of the metallic flange 3. In the antenna pattern according to the seventh example, arrangement locations of the orthogonal line 12 and the core-wire-side second line 13 of the core-wire-side element 10 are respectively different from those of the antenna pattern shown in FIG. 2 according to the second example. That is, as the differences therebetween, in the seventh example, the orthogonal line 12 is extended in a branched manner from an intermediate portion of the core-wire-side first line in a direction orthogonal to the core-wire-side first line. From a tip of this orthogonal line 12, the core-wire-side second line is extended in both of right and left directions.

[0085] On the other hand, the core-wire-side first line 11 and the ground-side element 20 and the like are same as those of the second example.

[0086] The antenna according to the seventh example was formed as follows, in the same manner as the second example. An electrically-conductive ceramic paste is printed on a predetermined location of an interior-side surface of the window glass plate. Then, the ceramic paste printed on the window glass plate is dried and burnt in the heating furnace.

[0087] The antenna for receiving the digital terrestrial radiobroadcast waves in the seventh example which was formed in the above processing was provided to the rear window glass of automobile. Then, the core-wire-side feeding point 6 was connected with a core conductor of a coaxial cable extended from a tuner (not shown) whereas the ground-side feeding point 7 was connected with an enveloping conductor of the coaxial cable. This antenna received the digital terrestrial radiobroadcast waves in the frequency range of the Band III which is ranging from 174 to 240 MHz. As a result, satisfactory receiving sensitivity was obtained to sufficiently satisfy the practical level, in the same manner as the second example.

[Eighth Example]

[0088] As shown in FIG. 13, near the upper edge of the opening of the metallic flange of the front window glass of automobile (vehicle), the core-wire-side feeding point 6 and the ground-side feeding point 7 of an antenna in an eighth example according to the present invention are aligned side-by-side along the upper edge. Then, the core-wire-side element 10 and the ground-side element 20 are extended respectively from the core-wire-side feeding point 6 and the ground-side feeding point 7 in the vertical direction. Each of the core-wire-side element 10 and the ground-side element 20 is bent (turned) at a right angle (90°) at an arbitrary point thereof. This structure is different from the seventh example in which the core-wire-side element 10 and the ground-side element 20 are simply extended respectively from the core-wire-side feeding point 6 and the ground-side feeding point 7 straightly in the horizontal direction. The lengths of the respective lines in the eighth example are equal to those in the seventh example.

[0089] The respective feeding points and the respective lines of the core-wire-side element 10 and the ground-side element 20 were formed as follows. An electrically-conductive ceramic paste is printed on a predetermined location of an interior-side surface of the window glass plate to cause a width of each line to become equal to 0.7 mm. Then, the ceramic paste printed on the window glass plate is dried and burnt in the heating furnace.

[0090] The antenna for receiving the digital terrestrial radiobroadcast waves in the eighth example which was formed in the above processing was provided to the front window glass of automobile. Then, the core-wire-side feeding point 6 was connected with a core conductor of a coaxial cable extended from a tuner (not shown) whereas the ground-side feeding point 7 was connected with an enveloping conductor of the coaxial cable. This antenna received the digital terrestrial radiobroadcast waves in the frequency range of the Band III which is ranging from 174 to 240 MHz.

[0091] FIG. 15 shows a frequency characteristic obtained by the antenna pattern of the eighth example (see FIG. 13) and a frequency characteristic obtained by the antenna pattern of the after-mentioned first comparative example (see FIG. 11), in the frequency range of the Band III.

[0092] As shown in FIG. 15, it can be understood that the receiving sensitivity shown by a solid line which is obtained by the antenna pattern of the eighth example according to the present invention is higher than a receiving sensitivity shown by a dotted line which is obtained by the antenna pattern of the first comparative example, over the entire frequency range of the Band III.

[0093] Although the invention has been described above with reference to the certain preferable examples (embodiments), the invention is not limited to the examples described above. Various variations of the above examples will occur according to teachings of the present invention.

[First Comparative Example]

[0094] As shown in FIG. 11, in the first comparative example, a core-wire-side element 10' is constituted only by a core-wire-side first line as shown in the first example according to the present invention (see FIG. 1). This core-wire-side first line has a length which causes resonance at an intermediate frequency of the Band III. The ground-side element 20 of the first comparative example is same as that of the pattern of the first example according to the present invention.

[0095] The antenna according to the first comparative example was formed as follows, in the same manner as the first example according to the present invention. An electrically-conductive ceramic paste is printed on a predetermined location of an interior-side surface of the window glass plate. Then, the ceramic paste printed on the window glass plate is dried and burnt in the heating furnace.

[0096] The antenna for receiving the digital terrestrial radiobroadcast waves in the first comparative example which was formed in the above processing was provided to the rear window glass of automobile. Then, the core-wire-side feeding point 6 was connected with a core conductor of a coaxial cable extended from a tuner (not shown) whereas the ground-side feeding point 7 was connected with an enveloping conductor of the coaxial cable. This antenna received the digital terrestrial radiobroadcast waves in the frequency range of the Band III which is ranging from 174 to 240 MHz. As a result, as shown in FIG. 12, the antenna of the first comparative example produced a frequency characteristic (shown by thin dotted line) lower than the frequency characteristic (shown by thick dotted line) of the first example according to the present invention. Accordingly, it became clear that the frequency characteristic of the first example according to the present invention is superior to that of the first comparative example.

[Configurations according to the Present Invention]

Some configurations obtainable from the above embodiments and examples will be listed below.

[0097] (1) A glass antenna for a vehicle, the glass antenna being of ungrounded-type and being configured to receive airwaves over an entire frequency bandwidth of a Band III of DAB standard for digital terrestrial radiobroadcast waves, the antenna comprising: core-wire-side and ground-side feeding points aligned close to each other on a glass surface of a window of the vehicle near an opening of a metallic flange of the window; a ground-side element including a line extending from the ground-side feeding point in a direction away from a portion of the metallic flange which is located closest to the ground-side feeding point; and a core-wire-side element including a core-wire-side first line extending from the core-wire-side feeding point substantially in parallel with the line of the ground-side element, and a core-wire-side second line extending from the core-wire-side first line in a branched manner or extending directly from the core-wire-side feeding point in parallel with the core-wire-side first line, wherein a length from the core-wire-side feeding point to a tip of the core-wire-side first line and a length from the core-wire-side feeding point to a tip of the core-wire-side second line correspond to two separate resonance frequencies within the frequency bandwidth to cause a resonance at each of the two separate resonance frequencies.

[0098] (2) The glass antenna as described in the above item (1), wherein each of the core-wire-side first line, the core-wire-side second line and the line of the ground-side element is bent at a certain point thereof in such a manner that the core-wire-side first line, the core-wire-side second line and the line of the ground-side element do not intersect with one another.

[0099] (3) The glass antenna as described in the above item (1) or (2), wherein each of the lengths is given by a relation α λ/4, where α denotes a wavelength compaction ratio of the glass and λ denotes a wavelength of the corresponding resonance frequency.

[0100] (4) The glass antenna as described in one of the above items (1) to (3), wherein the ground-side element is a rectangular closed-loop line.

[0101] (5) The glass antenna as described in one of the above items (1) to (4), wherein a tip portion of the core-wire-side second line of the core-wire-side element is connected with the core-wire-side first line to form a substantially rectangular closed-loop line.

[0102] (6) The glass antenna as described in one of the above items (1) to (5), wherein in a case that the antenna is provided near a horizontal edge of the opening of the metallic flange and near a corner of the opening, the ground-side feeding point is located closer to the corner whereas the core-wire-side feeding point is located farther from the corner and near the horizontal edge.

[0103] (7) The glass antenna as described in one of the above items (1) to (5), wherein in a case that the antenna is provided near a vertical edge of the opening of the metallic flange and near a corner of the opening, the ground-side feeding point is located closer to the corner whereas the core-wire-side feeding point is located farther from the corner and near the vertical edge.

[0104] (8) The glass antenna as described in one of the above items (1) to (5), wherein the antenna is provided at a location near an upper edge of the opening of the metallic flange for a front window glass of the vehicle.

[0105] (9) The glass antenna as described in one of the above items (1) to (5), wherein the antenna is provided at a location near a corner portion of the opening for a rear window glass of the vehicle.

[0106] (10) The glass antenna as described in one of the above items (1) to (5), wherein the antenna is provided in the opening for a non-opening window glass which constitutes a side window of the vehicle.

[0107] (11) The glass antenna as described in one of the above items (1) to (10), wherein a pattern of the antenna is formed of a transparent resin film or sheet having an adhesive face on which an electrically-conductive material is being printed, or on which wire lines are being stuck, and the pattern of the antenna is being stuck on the window glass surface of the vehicle.

(Advantageous Effects)

[0108] Although the Band III of DAB standard is defined by a low-frequency-level band which ranges from 174 to 240 MHz, the Band III has a broad bandwidth equal to 66MHz. In a case that an antenna is designed to resonate at only one resonance frequency which is a center value of the Band III, a frequency area(s) in which resonance cannot occur exists within the Band III because a frequency bandwidth over which resonance exceeding a certain level can occur is narrow. According to the present invention, two or more resonance frequencies at which the receiving characteristic takes peaks are set within the Band III to have a frequency spacing therebetween. Therefore, a frequency area(s) which is distant from the resonance frequency and hence in which the receiving sensitivity is low is reduced as compared with the case where only one resonance frequency is set within the Band III. Accordingly, the antenna according to the present invention can obtain good receiving characteristic over the entire range of the Band III.

EXPLANATION OF REFERENCE SIGNS

[0109] 

1

Window glass

2

Ceramic paste layer

3

Metallic flange

4

Defogger

6

Core-wire-side feeding point

7

Ground-side feeding point

10, 10'

Core-wire-side element

11

Core-wire-side first line

12

Orthogonal line

13

Core-wire-side second line

20

Ground-side element

21

Ground-side first line

Claims

1. A glass antenna for a vehicle, the glass antenna being of ungrounded-type and being configured to receive airwaves over an entire frequency bandwidth of a Band III of DAB standard for digital terrestrial radiobroadcast waves, the antenna comprising:

core-wire-side and ground-side feeding points aligned close to each other on a glass surface of a window of the vehicle near an opening of a metallic flange of the window;

a ground-side element including a line extending from the ground-side feeding point in a direction away from a portion of the metallic flange which is located closest to the ground-side feeding point; and

a core-wire-side element including
a core-wire-side first line extending from the core-wire-side feeding point substantially in parallel with the line of the ground-side element, and
a core-wire-side second line extending from the core-wire-side first line in a branched manner or extending directly from the core-wire-side feeding point in parallel with the core-wire-side first line,

wherein a length from the core-wire-side feeding point to a tip of the core-wire-side first line and a length from the core-wire-side feeding point to a tip of the core-wire-side second line correspond to two separate resonance frequencies within the frequency bandwidth to cause a resonance at each of the two separate resonance frequencies.

2. The glass antenna according to Claim 1, wherein
each of the core-wire-side first line, the core-wire-side second line and the line of the ground-side element is bent at a certain point thereof in such a manner that the core-wire-side first line, the core-wire-side second line and the line of the ground-side element do not intersect with one another.

3. The glass antenna according to Claim 1 or 2, wherein
each of the lengths is given by a relation α λ/4, where α denotes a wavelength compaction ratio of the glass and λ denotes a wavelength of the corresponding resonance frequency.

4. The glass antenna according to one of Claims 1 to 3, wherein
the ground-side element is a rectangular closed-loop line.

5. The glass antenna according to one of Claims 1 to 4, wherein
a tip portion of the core-wire-side second line of the core-wire-side element is connected with the core-wire-side first line to form a substantially rectangular closed-loop line.

6. The glass antenna according to one of Claims 1 to 5, wherein
in a case that the antenna is provided near a horizontal edge of the opening of the metallic flange and near a corner of the opening, the ground-side feeding point is located closer to the corner whereas the core-wire-side feeding point is located farther from the corner and near the horizontal edge.

7. The glass antenna according to one of Claims 1 to 5, wherein
in a case that the antenna is provided near a vertical edge of the opening of the metallic flange and near a corner of the opening, the ground-side feeding point is located closer to the corner whereas the core-wire-side feeding point is located farther from the corner and near the vertical edge.

8. The glass antenna according to one of Claims 1 to 5, wherein
the antenna is provided at a location near an upper edge of the opening of the metallic flange for a front window glass of the vehicle.

9. The glass antenna according to one of Claims 1 to 5, wherein
the antenna is provided at a location near a corner portion of the opening for a rear window glass of the vehicle.

10. The glass antenna according to one of Claims 1 to 5, wherein
the antenna is provided in the opening for a non-opening window glass which constitutes a side window of the vehicle.

11. The glass antenna according to one of Claims 1 to 10, wherein
a pattern of the antenna is formed of a transparent resin film or sheet having an adhesive face on which an electrically-conductive material is being printed, or on which wire lines are being stuck, and
the pattern of the antenna is being stuck on the window glass surface of the vehicle.

Drawing