FIELD OF THE INVENTION
[0001] The invention relates to a glass antenna for vehicle, particularly to an antenna
for a motor vehicle which has an digital TV antenna (television).
RELATED ART
[0002] In the prior art, there is disclosed a glass antenna arrangement for vehicle comprising
a defogger having heat wires for defogging, an AM antenna which is formed in the upper
area of the defogger, and a FM antenna which is arranged between the defogger and
the AM antenna (for example, refer to PCT National-phase Japanese Publication No.
2003-500870).
[0003] As shown in Fig. 1, the glass antenna arrangement 1, for example, comprises a glass
antenna for a motor vehicle, a signal-amplifying means 7, and a receiver 10. The glass
antenna for a motor vehicle includes in the surface of a rear-window glass 2 an AM
antenna 4 for receiving of the signal of AM band provided in the upper area of the
defogger 3 with a plurality of heat wires 3e for defogging, and a FM antenna 5 for
receiving of the signal of FM band provided between the heat wires 3e and the AM antenna
4.
[0004] The signal-amplifying means 7 includes an AM-amplifying means 8 for amplifying through
a feeding point 4b the signal of AM-electromagnetic wave received by a plurality of
AM-horizontal conductors 4a, and a FM-amplifying means 9 for amplifying through a
feeding point 5a the signal of FM-electromagnetic wave received by the FM-horizontal
conductors 5 composed of one horizontal pattern.
[0005] The receiver 10 receives, for example through a coaxial cable, the signal of AM or
FM band from the signal-amplifying means 7, and then converts the received signal
into the visual or audio signal, accordingly.
[0006] The defogger 3 comprises bus bars 3a and 3b mutually faced, which are arranged over
the top-to-bottom direction on the both sides of a window glass of the motor vehicle,
feeding points 3c and 3d provided to apply the voltage V
H to the respective bus bars 3 a and 3b by means of a power supply 6 for the heat wires,
and the plurality of heat wires 3e horizontally arranged between the bus bars 3a and
3b.
[0007] Moreover, the signal-receiving sensitivity of the AM band tends to be proportional
to the area covered by the AM-horizontal conductors of the AM antenna, and therefore
the specified length or gross area of the AM-horizontal conductors is requested to
be a desired extent.
DISCLOSURE OF INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0008] Recently, it is considered to provide in the upper area of the AM antenna of the
window glass for vehicle an antenna appropriate to the reception of the electromagnetic
wave of Television Broadcasting (TV electromagnetic wave).
[0009] However, when such an antenna appropriate to the reception of TV electromagnetic
wave is provided in the upper area of the AM antenna, the AM antenna may influence
the sensitivity characteristic of the antenna appropriate to the reception of TV electromagnetic
wave.
[0010] This phenomenon may be considered as follows. When an antenna for digital terrestrial
TV broadcasting (hereinafter, it is referred to as the digital TV antenna) is arranged
in the upper area of the AM antenna with the horizontal conductors on the rear-window
glass, the directivity of the signal-receiving sensitivity of the digital TV antenna
changes into a vertical direction with respect to the rear-window glass (i.e., a direction
indicated in the dotted line) as shown in Fig. 2, and thus the signal-receiving sensitivity
of the digital TV antenna may be decreased.
[0011] That is, since the sensitivity of the horizontal direction of the digital TV antenna
is decreased by the influence of the AM antenna with the horizontal conductors, the
directivity of the signal-receiving sensitivity of the digital TV antenna may be changed
into a vertical direction to the rear-window glass. As a result, there is caused the
problem that the directivity control into the direction of the desired wave in the
digital TV antenna becomes difficult, and thus the sensitivity of the digital TV antenna
may be decreased.
[0012] Therefore, the invention is to provide a glass antenna for vehicle which comprises
a digital TV antenna appropriate to the reception of TV electromagnetic wave with
excellent sensitivity of the horizontal direction, and an AM antenna in the limited
area of a rear-window glass.
MEANS FOR SOLVING THE PROBLEM
[0013] There is provided a glass antenna for vehicle in an aspect according to the invention,
the glass antenna being formed on the surface of a window glass for vehicle in which
a defogger with a plurality of heat wires extended over a horizontal direction is
provided, the glass antenna being characterized in that it comprises a first antenna
for receiving of TV electromagnetic wave, wherein the first antenna includes a horizontal
element formed at the side of the heat wires and substantially parallel to the plurality
of heat wires; and a second antenna for receiving of AM electromagnetic wave formed
between the defogger and the first antenna, wherein the second antenna includes a
discontinuous region closely located at the first antenna.
[0014] Moreover, the glass antenna for vehicle in the aspect according to the invention
is characterized in that the second antenna includes in the discontinuous region at
least one continuous-horizontal conductor and at least one continuous-horizontal conductor
located in parallel to the continuous-horizontal conductor.
[0015] Moreover, the glass antenna for vehicle in the aspect according to the invention
is characterized in that the second antenna includes in the discontinuous region at
least one gamma-shaped antenna element which is composed of a vertical conductor and
a partial, horizontal conductor.
[0016] Moreover, the glass antenna for vehicle in the aspect according to the invention
is characterized in that the second antenna includes in the discontinuous region a
continuous meander-shaped antenna element composed of vertical conductors and partial,
horizontal conductors.
[0017] Moreover, the glass antenna for vehicle in the aspect according to the invention
is characterized in that the first antenna includes a L-shaped or loop-shaped antenna
element, wherein the horizontal element is a part of the L-shaped or loop-shaped antenna
element.
[0018] Moreover, the glass antenna for vehicle in the aspect according to the invention
is characterized in that the horizontal element comprises a plurality of conductive
elements, each of the conductive elements being mutually capacitive-coupled.
[0019] Moreover, the glass antenna for vehicle in the aspect according to the invention
is characterized in that the second antenna includes in the discontinuous region at
least one vertical conductor, the vertical conductor being electrically connected
to the continuous-horizontal conductor.
[0020] Moreover, the glass antenna for vehicle in the aspect according to the invention
is characterized in that the clearance of the horizontal direction between the horizontal
element and the discontinuous-horizontal conductor is from 0 to 75 mm, as the distance
along the surface of the window glass for vehicle.
[0021] Moreover, the glass antenna for vehicle in the aspect according to the invention
is characterized in that the clearance of the vertical direction between the horizontal
element and the continuous-horizontal conductor is larger than 10 mm, and is smaller
than 135 mm, as the distance along the surface of the window glass for vehicle.
[0022] Preferably, the glass antenna for vehicle in the aspect according to the invention
is provided, so that the clearance of the vertical direction between the horizontal
element and the continuous-horizontal conductor is larger than 10 mm, and is smaller
than 135 mm, as the distance along the surface of the window glass for vehicle. More
preferably, the glass antenna for vehicle in the aspect according to the invention
is provided, so that the clearance of the vertical direction between the horizontal
element and the continuous-horizontal conductor is larger than 45 mm, and is smaller
than 135 mm, as the distance along the surface of the window glass for vehicle.
EFFECT OF THE INVENTION
[0023] A glass antenna for vehicle can be provided, the glass antenna comprising a digital
TV antenna appropriate to the reception of TV electromagnetic wave with excellent
sensitivity of the horizontal direction, and an AM antenna in the limited area of
a rear-window glass of a motor vehicle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024]
Fig. 1 is a diagram showing an example of a conventional glass antenna arrangement
for vehicle;
Fig. 2 is a diagram showing the directivity of the signal-receiving sensitivity of
a digital TV antenna;
Fig. 3 is a schematic diagram of a glass antenna for vehicle in a first embodiment
according to the invention;
Fig. 4 is a schematic diagram of a glass antenna for vehicle in a second embodiment
according to the invention;
Fig. 5 is a schematic diagram of a glass antenna for vehicle in a third embodiment
according to the invention;
Fig. 6 is a schematic diagram of a glass antenna for vehicle in a fourth embodiment
according to the invention;
Fig. 7 is a schematic diagram of a glass antenna for vehicle in a first comparative
example;
Fig. 8 is a comparative graph of the measurement result of the sensitivity characteristic
of the digital TV antenna with changed values of x1 and x2 in the glass antenna for vehicle shown in Fig. 6;
Fig. 9 is a comparative graph of the measurement result of the sensitivity characteristic
of the digital TV antenna in each of the glass antennas for vehicle shown in the first
comparative example, the third embodiment and the fourth embodiment, respectively;
Fig. 10 is a schematic diagram of a glass antenna for vehicle in a fifth embodiment
according to the invention;
Fig. 11 is a schematic diagram of a glass antenna for vehicle in a sixth embodiment
according to the invention;
Fig. 12 is a schematic diagram of a glass antenna for vehicle in a second comparative
example;
Fig. 13 is a comparative graph of the measurement result of the sensitivity characteristic
of the digital TV antenna in each of the glass antennas for vehicle shown in the second
comparative example, the fifth embodiment and the sixth embodiment, respectively;
Fig. 14 is a schematic diagram of a glass antenna for vehicle in a seventh embodiment
according to the invention;
Fig. 15 is a schematic diagram of a glass antenna for vehicle in an eighth embodiment
according to the invention;
Fig. 16 is a schematic diagram of a glass antenna for vehicle in a ninth embodiment
according to the invention;
Fig. 17 is a schematic diagram of a glass antenna for vehicle in a tenth embodiment
according to the invention;
Fig. 18 is a schematic diagram of a glass antenna for vehicle in a third comparative
example;
Fig. 19 is a comparative graph of the measurement result of the sensitivity characteristic
of the digital TV antenna in each of the glass antennas for vehicle shown in the third
comparative example, the seventh to tenth embodiments, respectively;
Fig. 20 is a schematic diagram of a glass antenna for vehicle comprising a digital
TV antenna of dipole antenna type in one embodiment according to the invention;
Fig. 21 is a schematic diagram of a glass antenna for vehicle comprising a digital
TV antenna of monopole antenna type having parasitic elements in one embodiment according
to the invention; and
Fig. 22 is a schematic diagram of a glass antenna for vehicle comprising digital TV
antennas which are arranged at both sides of a window glass for vehicle in one embodiment
according to the invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0025] Hereinafter, each embodiment of the invention is described in reference to each drawing.
The same numerals are fixed to similar components or elements in each drawing.
[0026] According to the embodiment described later, a digital TV antenna has an excellent
sensitivity characteristic in the limited area of a rear-window glass 2, hardly deteriorating
the necessary performance of an AM antenna.
[0027] Firstly, a glass antenna for vehicle of a first embodiment in accordance with the
invention is described.
(FIRST EMBODIMENT)
[0028] Fig. 3 shows a schematic diagram of a glass antenna for vehicle in a first embodiment
according to the invention. The glass antenna for vehicle of the first embodiment
is formed on the surface of a rear-window glass 2 for vehicle in which a defogger
3 with a plurality of heat wires 3e extended over a horizontal direction of the rear-window
glass 2 is provided. The glass antenna comprises a digital TV antenna (a first antenna)
18 for receiving of TV electromagnetic wave, and an AM antenna (a second antenna)
4 for receiving of AM electromagnetic wave, in which the digital TV antenna 18 includes
a horizontal element 18c formed essentially parallel to the plurality of heat wires
3e of the defogger, and the AM antenna 4 is formed between the defogger 3 and the
digital TV antenna 18. Moreover, a FM antenna 5 is arranged between the defogger 3
and the AM antenna 4.
[0029] As shown in Fig. 3, the defogger 3 with the plural heat wires 3e (at regular intervals
of 15-40 mm) for defogging is provided to be enough width for field of view in the
rear-window glass 2 of one vehicle (for example, a passenger car), in which the FM
antenna 5 and the AM antenna 4 are arranged over the defogger 3. The defogger 3 may
include a shorting bar 3f to which each of the plurality of heat wires 3e is mutually
connected.
[0030] Moreover, the FM antenna 5 is closely arranged for capacitive-coupling with the heat
wire, which is located in top-level of the plurality of heat wires 3e, to improve
the signal-receiving sensitivity (at the distance of about 5-10 mm). In addition,
the distance between the AM antenna 4 and the defogger 3 is maintained by, for example,
30 mm, and each of horizontal conductors 4a of the AM antenna has the width of 60
mm. Hereinafter, the direction substantially orthogonal to the horizontal direction
along the window glass of the vehicle is referred to as a vertical direction.
[0031] The digital TV antenna 18 is composed as a monopole antenna of 1/4 wavelength, and
comprises a ground pattern 18a electrically connected to the ground portion of the
vehicle (for example, the ground pattern 18a being formed as a L-shape), an antenna
element that includes a horizontal element 18c for receiving of the signal carrier
of digital terrestrial TV broadcasting, and an amplifier 18b for amplifying of the
signal from the digital TV antenna (the amplifier 18b being arranged between the ground
pattern 18a and said antenna element). The output from the amplifier 18b is received,
for example through a coaxial cable (not shown), by means of the receiver, and is
converted into the visual or audio signal, accordingly.
[0032] Preferably, the length of the L-shaped antenna element for the antenna element in
the monopole antenna of 1/4 wavelength is within 60-150 mm in case of the shortening
rate of 60% caused by the glass material, to resonate by frequency bands (470-770
MHz) of the signal carrier of digital terrestrial TV broadcasting, and the length
may be, for example, 80 mm. In addition, while the horizontal element 18c of the L-shaped
antenna element may be formed by the length with extremely near 0 mm, the length of
the horizontal element 18c may be preferably the half-length of said length of the
L-shaped antenna element to improve the signal-receiving performance of the horizontal
polarized electromagnetic radiation, such as, for example, 40 mm.
[0033] The AM antenna 4 comprises a plurality of horizontal conductors, which are electrically
connected to a feeding point 4b and being extended in substantially parallel to the
horizontal element 18c, and a shorting bar 4f which is extended in substantially orthogonal
direction with respect to the plurality of horizontal conductors.
[0034] In addition, the AM antenna 4 in the first embodiment includes a given region where
the horizontal conductor is discontinuous (hereinafter, it is referred to as a discontinuous
region 4g), closely located at the digital TV antenna 18 (the discontinuous region
4g in the first embodiment is a region where the horizontal conductor has not been
provided). In addition, the horizontal conductor with the edge of the discontinuous
region 4g is referred to as a continuous-horizontal conductor 4c, and the horizontal
conductor other than the continuous-horizontal conductor 4d is referred to as a continuous-horizontal
conductor 4c. That is, the plural horizontal conductors are composed of at least one
continuous-horizontal conductor 4c and at least one continuous-horizontal conductor
4d. As shown in Fig. 3, the discontinuous region 4g in the first embodiment is located
under the digital TV antenna 18, and is arranged over the plurality of continuous-horizontal
conductors 4d.
[0035] Moreover, there is defined the physical relationship among the horizontal element
18c of the digital TV antenna 18, the continuous-horizontal conductors 4c and the
continuous-horizontal conductors 4d in the AM antenna 4. More specifically, the physical
relationship may be specified by defining the clearance of the horizontal direction,
x
1 and x
2, between the horizontal element 18c and the discontinuous-horizontal conductor 4c
as the distance along the surface of the window glass for vehicle, and defining the
clearance of the vertical direction, y, between the horizontal element 18c and the
continuous-horizontal conductor 4d located under the discontinuous region 4g, as the
distance of the direction along the surface of the window glass for vehicle.
[0036] Thus, providing of the discontinuous region 4g into the AM antenna 4 enables to improve
the sensitivity characteristic of the digital TV antenna 18. Moreover, the physical
relationship among the horizontal element 18c, the continuous-horizontal conductors
4c and the continuous-horizontal conductors 4d may be also defined by these x
1, x
2, and y, as described later.
[0037] Then, a glass antenna for vehicle of a second embodiment in accordance with the invention
is described.
(SECOND EMBODIMENT)
[0038] Fig. 4 shows a schematic diagram of a glass antenna for vehicle in a second embodiment
according to the invention. The arrangement of the glass antenna for vehicle of the
second embodiment is similar with that of the first embodiment, other than the size
of the discontinuous region 4g, and thus its similar description is omitted. As shown
in Fig. 4, the discontinuous region 4g in the second embodiment is located under the
digital TV antenna 18, and is arranged over one continuous-horizontal conductor 4d.
[0039] Thus, the value of the distance, y, of the glass antenna in the second embodiment
is larger than that of the glass antenna in the first embodiment. The larger value
of the distance, y, enables to further improve the sensitivity characteristic of the
digital TV antenna 18, as described later.
[0040] Then, a glass antenna for vehicle of a third embodiment in accordance with the invention
is described.
(THIRD EMBODIMENT)
[0041] Fig. 5 shows a schematic diagram of a glass antenna for vehicle in a third embodiment
according to the invention. The arrangement of the glass antenna for vehicle of the
third embodiment is similar with that of the first embodiment, other than the configuration
of the discontinuous region 4g, and thus its similar description is omitted. As shown
in Fig. 5, the discontinuous region 4g in the third embodiment is located under the
horizontal element 18c of the digital TV antenna 18, and is arranged over the plurality
of continuous-horizontal conductors 4d.
[0042] In addition, the continuous-horizontal conductor at the top-level of the plurality
of continuous-horizontal conductors 4d includes in the discontinuous region 4g at
least one vertical conductor 4h. The vertical conductors 4h may be formed upon the
plurality of continuous-horizontal conductors 4d.
[0043] Thus, providing of the discontinuous region 4g into the AM antenna 4 enables to improve
the sensitivity characteristic of the digital TV antenna 18. Moreover, providing of
the vertical conductors 4h into the discontinuous region 4g enables to prevent the
deterioration of sensitivity characteristic of the AM antenna 4.
[0044] Then, a glass antenna for vehicle of a fourth embodiment in accordance with the invention
is described.
(FOURTH EMBODIMENT)
[0045] Fig. 6 shows a schematic diagram of a glass antenna for vehicle in a fourth embodiment
according to the invention. The arrangement of the glass antenna for vehicle of the
fourth embodiment is similar with that of the second embodiment, other than the configuration
of the discontinuous region 4g, and thus its similar description is omitted. As shown
in Fig. 6, the discontinuous region 4g in the fourth embodiment is located under the
horizontal element 18c of the digital TV antenna 18, and is arranged over one continuous-horizontal
conductor 4d.
[0046] In addition, the continuous-horizontal conductor 4d includes in the discontinuous
region 4g at least one vertical conductor 4h.
[0047] Thus, providing of the discontinuous region 4g into the AM antenna 4 enables to improve
the sensitivity characteristic of the digital TV antenna 18. Moreover, providing of
the vertical conductor 4h into the discontinuous region 4g enables to prevent the
deterioration of sensitivity characteristic of the AM antenna 4.
[0048] Then, a first comparative example of a glass antenna for vehicle is described hereinafter
to make the effect of the first to fourth embodiments clearer. The same numerals are
fixed to similar components or elements in this description.
(FIRST COMPARATIVE EXAMPLE)
[0049] Fig. 7 shows a first comparative example in which the digital TV antenna is arranged
over a conventional glass antenna for vehicle. The conventional glass antenna for
vehicle of the first comparative example comprises the digital TV antenna 18, the
AM antenna 4, and the FM antenna 5 on the window glass for vehicle with the defogger
3 as shown in Fig. 7, in similar with the above-described embodiments. In addition,
the defogger 3, the digital TV antenna 18 and the FM antenna 5 are similar with the
configuration shown in the above-described embodiments, and thus these descriptions
are omitted.
[0050] In the first comparative example shown in Fig. 7, the horizontal conductor of the
AM antenna 4 is composed of only continuous-horizontal conductors. Moreover, the distance
between the horizontal conductor at the top-level of the horizontal conductors in
the AM antenna 4 and the digital TV antenna is 45 mm.
[0051] The measurement result of the sensitivity characteristic of the digital TV antenna
or the AM antenna is now described as follows, specifying the physical relationship
(x
1, x
2, y) defined by x
1, x
2, and y for the description of the specific effect in relation to each of the above-described
embodiments.
[0052] Fig. 8 shows a comparative graph of the measurement result of the sensitivity characteristic
of the digital TV antenna with changed values of x
1 and x
2 in each glass antenna for vehicle shown in Fig. 7 (the first comparative example)
and in Fig. 6 (the fourth embodiment), respectively. Moreover, the numeric measurement
result corresponding to Fig. 8 is shown in Table 1 (the unit is dBi). In addition,
the mean value, the minimum value, and the maximum value of the sensitivity characteristic
corresponding to Table 1 are shown in Table 2 (the unit is dBi). In addition, each
measurement result representing the ratio of the signal-receiving sensitivity based
on the measurement result of the average sensitivity received with the dipole antenna
is shown in Fig. 8, in Table 1, and in Table 2. Besides, the glass antenna for vehicle
as the first comparative example shown in Fig. 7 corresponds to y=45 mm. As to the
measurement result in Fig. 8, the measurement result of the glass antenna for vehicle
shown in Fig. 6 (the fourth embodiment) is the measurement values in case of y=105
mm, and with changed values between x
1= x
2=10 to 100 mm.
[0053]
[Table 1]
(dBi) |
Frequency [MHz] |
Average Sensitivity |
1st Comparative Example(Fig.7) |
x1=x2=10mm |
x1=x2=25mm |
x1=x2=50mm |
x1=x2=75mm |
x1=x2=100mm |
470 |
-12.4 |
-9.6 |
-10.2 |
-10.8 |
-11.0 |
-11.1 |
480 |
-12.6 |
-10.4 |
-10.0 |
-10.5 |
-10.7 |
-10.8 |
490 |
-11.2 |
-10.0 |
-9.4 |
-9.6 |
-9.7 |
-9.8 |
500 |
-10.7 |
-8.4 |
-8.4 |
-8.9 |
-9.0 |
-9.1 |
510 |
-10.4 |
-8.4 |
-8.0 |
-8.3 |
-8.4 |
-8.4 |
520 |
-8.9 |
-7.7 |
-7.0 |
-6.9 |
-6.9 |
-6.8 |
530 |
-8.1 |
-7.2 |
-6.5 |
-6.4 |
-6.4 |
-6.3 |
540 |
-7.3 |
-5.5 |
-4.8 |
-4.9 |
-5.1 |
-5.0 |
550 |
-8.3 |
-6.9 |
-6.7 |
-6.4 |
-6.6 |
-6.6 |
560 |
-7.9 |
-6.4 |
-6.1 |
-5.9 |
-6.0 |
-6.2 |
570 |
-8.6 |
-6.9 |
-7.1 |
-6.8 |
-6.7 |
-6.8 |
580 |
-8.6 |
-7.0 |
-6.7 |
-7.0 |
-6.8 |
-6.9 |
590 |
-9.4 |
-7.0 |
-7.2 |
-7.4 |
-7.2 |
-7.3 |
600 |
-10.0 |
-7.2 |
-7.2 |
-7.4 |
-7.4 |
-7.5 |
610 |
-10.4 |
-8.3 |
-7.7 |
-7.4 |
-7.6 |
-7.6 |
620 |
-10.5 |
-9.0 |
-8.4 |
-7.5 |
-7.5 |
-7.5 |
630 |
-11.2 |
-9.6 |
-9.0 |
-8.0 |
-8.2 |
-8.1 |
640 |
-9.9 |
-8.7 |
-8.3 |
-7.4 |
-7.3 |
-7.3 |
650 |
-10.5 |
-8.8 |
-8.9 |
-8.2 |
-7.7 |
-7.8 |
660 |
-9.4 |
-7.6 |
-7.4 |
-6.9 |
-6.5 |
-6.6 |
670 |
-9.1 |
-7.6 |
-6.8 |
-6.5 |
-6.0 |
-6.1 |
680 |
-9.0 |
-9.2 |
-7.3 |
-6.6 |
-6.4 |
-6.3 |
690 |
-8.2 |
-8.8 |
-7.8 |
-6.8 |
-6.7 |
-6.3 |
700 |
-7.2 |
-7.2 |
-6.8 |
-6.0 |
-6.0 |
-5.8 |
710 |
-7.6 |
-6.9 |
-6.4 |
-5.7 |
-5.7 |
-5.7 |
720 |
-8.9 |
-7.9 |
-7.4 |
-6.7 |
-6.4 |
-6.5 |
740 |
-10.7 |
-8.0 |
-8.0 |
-7.6 |
-7.5 |
-7.5 |
750 |
-10.9 |
-8.7 |
-8.6 |
-8.4 |
-8.3 |
-8.2 |
760 |
-10.4 |
-9.0 |
-9.0 |
-8.9 |
-8.9 |
-8.7 |
770 |
-9.7 |
-8.9 |
-9.0 |
-8.8 |
-8.9 |
-8.6 |
[0054]
[Table 2]
(dBi) |
Average Sensitivity |
1st Comparative Example(Fig.7) |
x1=x2=10mm |
x1=x2=25mm |
x1=x2=50mm |
x1=x2=75mm |
x1=x2=100mm |
Mean Value |
-9.6 |
-8.1 |
-7.7 |
-7.5 |
-7.4 |
-7.4 |
Min. Value |
-12.6 |
-10.4 |
-10.2 |
-10.8 |
-11.0 |
-11.1 |
Max. Value |
-7.2 |
-5.5 |
-4.8 |
-4.9 |
-5.1 |
-5.0 |
[0055] It should be understood from Fig. 8, Table 1, and Table 2 that the sensitivity characteristic
of the digital TV antenna is improved by providing the AM antenna 4 with the discontinuous
region 4g and increasing x
1 and x
2, compared with the glass antenna for vehicle shown in Fig. 7 (the first comparative
example).
[0056] In addition, it should be understood that the minimum value of the average sensitivity
becomes larger than -11.0 preferably, when the clearance of x
1 and x
2 for defining the discontinuous region 4g is from 0 to 75 mm.
[0057] Fig. 9 shows a comparative graph of the measurement result of the sensitivity characteristic
of the digital TV antenna in each glass antenna for vehicle shown in Fig. 7 (the first
comparative example), in Fig. 5 (the third embodiment) and in Fig. 6 (the fourth embodiment),
respectively. Moreover, the numeric measurement result corresponding to Fig. 9 is
shown in Table 3 (the unit is dBi). In addition, the mean value, the minimum value,
and the maximum value of the sensitivity characteristic corresponding to Table 3 are
shown in Table 4 (the unit is dBi). In addition, each measurement result representing
the ratio of the signal-receiving sensitivity based on the measurement result of the
mean value (the average of signal-receiving sensitivity) received with the dipole
antenna is shown in Fig. 9, in Table 3, and in Table 4 respectively, where the mean
value is value averaged by 180 degrees over the horizontal direction of the digital
TV antenna in the outside direction of the vehicle (i.e., the signal-receiving sensitivity
measured from the sideward of the vehicle to the backward thereof). As described above,
the glass antenna for vehicle as the first comparative example shown in Fig. 7 corresponds
to y=45 mm. As to the measurement result in Fig. 9, each measurement result of the
glass antenna for vehicle shown in Fig. 5 (the third embodiment) and in Fig. 6 (the
fourth embodiment) corresponds to the measurement value in case of x
1= x
2=50 mm, y=65 mm (Fig. 5), and y=105 mm (Fig. 6) respectively.
[0058]
[Table 3]
(dBi) |
Frequency |
Average Sensitivity |
[MHz] |
1st Comparative Example(Fig.7) |
3rd Embodiment (Fig. 5) |
4th Embodiment (Fig. 6) |
470 |
-12.4 |
-11.6 |
-10.8 |
480 |
-12.6 |
-12.1 |
-10.5 |
490 |
-11.2 |
-10.5 |
-9.6 |
500 |
-10.7 |
-10.0 |
-8.9 |
510 |
-10.4 |
-9.3 |
-8.3 |
520 |
-8.9 |
-7.9 |
-6.9 |
530 |
-8.1 |
-7.4 |
-6.4 |
540 |
-7.3 |
-5.8 |
-4.9 |
550 |
-8.3 |
-7.3 |
-6.4 |
560 |
-7.9 |
-7.0 |
-5.9 |
570 |
-8.6 |
-7.4 |
-6.8 |
580 |
-8.6 |
-7.1 |
-7.0 |
590 |
-9.4 |
-7.6 |
-7.4 |
600 |
-10.0 |
-8.5 |
-7.4 |
610 |
-10.4 |
-9.1 |
-7.4 |
620 |
-10.5 |
-8.7 |
-7.5 |
630 |
-11.2 |
-9.0 |
-8.0 |
640 |
-9.9 |
-7.9 |
-7.4 |
650 |
-10.5 |
-9.0 |
-8.2 |
660 |
-9.4 |
-8.2 |
-6.9 |
670 |
-9.1 |
-7.7 |
-6.5 |
680 |
-9.0 |
-7.8 |
-6.6 |
690 |
-8.2 |
-7.4 |
-6.8 |
700 |
-7.2 |
-6.6 |
-6.0 |
710 |
-7.6 |
-6.3 |
-5.7 |
720 |
-8.9 |
-7.1 |
-6.7 |
730 |
-10.1 |
-7.4 |
-7.1 |
740 |
-10.7 |
-8.1 |
-7.6 |
750 |
-10.9 |
-9.1 |
-8.4 |
760 |
-10.4 |
-9.9 |
-8.9 |
770 |
-9.7 |
-9.6 |
-8.8 |
[0059]
[Table 4]
Average Sensitivity |
1st Comparative Example(Fig.7) |
3rdEmbodiment (Fig. 5) |
4th Embodiment (Fig. 6) |
Mean Value |
-9.6 |
-8.3 |
-7.5 |
Min. Value |
-12.6 |
-12.1 |
-10.8 |
Max. Value |
-7.2 |
-5.8 |
-4.9 |
[0060] It should be understood from Fig. 9 and Table 3 that the sensitivity characteristic
of the digital TV antenna is improved by providing the AM antenna 4 with the discontinuous
region 4g and increasing the value y.
[0061] It should be understood from Table 4 that the sensitivity characteristic of the digital
TV antenna of the glass antenna shown in Fig. 5 (the third embodiment) is improved
by 1.3 dB as the average sensitivity of the digital TV antenna, compared with the
glass antenna for vehicle shown in Fig. 7(the first comparative example). Moreover,
it should be understood from Table 4 that the sensitivity characteristic of the digital
TV antenna of the glass antenna shown in Fig. 6 (the fourth embodiment) is improved
by 2.1 dB as the average sensitivity of the digital TV antenna, compared with the
glass antenna for vehicle shown in Fig. 7(the first comparative example).
[0062] Moreover, taking into account the limited area of the antenna arrangement of the
glass antenna for vehicle, it should be understood from Table 4 that the clearance
of y defining the discontinuous region is larger than 45 mm, and is smaller than 135
mm, preferably.
[0063] Then, the sensitivity characteristic of the AM antenna by providing the AM antenna
with the discontinuous region 4g is described.
[0064] Table 5 shows comparative values of the measurement result of the sensitivity characteristic
of the digital TV antenna in each glass antenna for vehicle shown in Fig. 7 (the first
comparative example), in Fig. 4 (the second embodiment), and in Fig. 6 (the fourth
embodiment), respectively (the unit is dBµV). As described above, the glass antenna
for vehicle as the first comparative example shown in Fig. 7 corresponds to y=45 mm.
Each measurement result of the glass antenna for vehicle shown in Fig. 4 (the second
embodiment) and in Fig. 6 (the fourth embodiment) corresponds to the measurement value
in case of x
1= x
2=50 mm, and y=105 mm (Fig. 4 and Fig. 6).
[0065]
[Table 5]
(dB µV) |
|
594KHz |
954KHz |
1242KHz |
1458KHz |
Mean Value |
Min. Value |
1st Comparative Example (Fig. 7) |
31.2 |
30.5 |
31.3 |
33.6 |
31.7 |
30.5 |
2nd Embodiment (Fig. 4) |
30.3 |
29.6 |
30.5 |
32.8 |
30.8 |
29.6 |
4th Embodiment (Fig. 6) |
31.1 |
30.4 |
31.3 |
33.5 |
31.6 |
30.4 |
[0066] It should be understood from Table 5 that the providing of the discontinuous region
4g into the AM antenna have little to do with the influence of the AM signal-receiving
sensitivity. Moreover, as described in the fourth embodiment (Fig. 6), it should be
understood that the signal-receiving sensitivity of the AM antenna significantly equal
to the first comparative example (Fig. 7) is obtained by providing the vertical conductor
4h into the discontinuous region 4g of the AM antenna 4.
[0067] Moreover, according to the glass antenna for vehicle in the first to fourth embodiments,
providing of the discontinuous region 4g into the AM antenna enables to change the
directivity of the digital TV antenna 18 into the direction vertical to the surface
of the rear-window glass, and to control said directivity into the direction of the
desired wave of the digital TV antenna.
[0068] The connection between the vertical conductors 4h and the continuous-horizontal conductors
4d may be electrical connection by the capacitive-coupling, while it is described
to maintain the connection by the physical connection in the above described third
and fourth embodiments. Moreover, parasitic elements may be closely located at the
vertical conductors 4h so as to assist the vertical conductors 4h.
[0069] Then, a glass antenna for vehicle of a fifth embodiment in accordance with the invention
is described.
(FIFTH EMBODIMENT)
[0070] Fig. 10 shows a schematic diagram of a glass antenna for vehicle in a fifth embodiment
according to the invention. The arrangement of the glass antenna for vehicle of the
fifth embodiment is similar with that of the third embodiment, other than the configuration
of the digital TV antenna, and thus its similar description is omitted. As shown in
Fig. 10, the digital TV antenna 58 of the fifth embodiment comprises a loop-conductive
element 58c with horizontal elements; a vertical-conductive element to which the loop-conductive
element 58c and a feeding point are connected; an auxiliary-conductive element 58d
extended from the vertical-conductive element; and a parasitic element 58e to which
the auxiliary-conductive element 58d and the loop-conductive element 58c are capacitive-coupled.
[0071] As shown in Fig. 10 of the glass antenna of the fifth embodiment, the clearance of
the vertical direction, y, between the horizontal element of the loop-conductive element
58c and the continuous-horizontal conductor 4d is maintained by 30 mm. Moreover, the
clearance of the horizontal direction, x, between the horizontal element of the loop-conductive
element 58c and the discontinuous-horizontal conductor 4c is provided from 0 to 75
mm, as the distance along the surface of the window glass for vehicle.
[0072] Then, a glass antenna for vehicle of a sixth embodiment in accordance with the invention
is described.
(SIXTH EMBODIMENT)
[0073] Fig. 11 shows a schematic diagram of a glass antenna for vehicle in a sixth embodiment
according to the invention. The arrangement of the glass antenna for vehicle of the
sixth embodiment is similar with that of the fourth embodiment, other than the configuration
of the digital TV antenna, and thus its similar description is omitted. Moreover,
the glass antenna of the sixth embodiment comprises the digital TV antenna 58 similar
with that of the fifth embodiment.
[0074] As shown in Fig. 11 of the glass antenna of the sixth embodiment, the clearance of
the vertical direction, y, between the horizontal element of the loop-conductive element
58c and the continuous-horizontal conductor 4d is maintained by 70 mm. Moreover, the
clearance of the horizontal direction, x, between the horizontal element of the loop-conductive
element 58c and the discontinuous-horizontal conductor 4c is provided from 0 to 75
mm, as the distance along the surface of the window glass for vehicle.
[0075] Then, a second comparative example of a glass antenna for vehicle is described hereinafter
to make the effect of the fifth and sixth embodiments clearer. The same numerals are
fixed to similar components or elements in this description.
(SECOND COMPARATIVE EXAMPLE)
[0076] Fig. 12 shows a schematic diagram of a glass antenna for vehicle in a second comparative
example. The arrangement of the glass antenna for vehicle of the second comparative
example shown in Fig. 12 is similar with the above-described arrangement shown in
Fig. 7, other than the configuration of the digital TV antenna, and thus its similar
description is omitted. Moreover, the glass antenna of the second comparative example
shown in Fig. 12 comprises the digital TV antenna 58 similar with that of the fifth
or sixth embodiment.
[0077] As shown in Fig. 12 of the second comparative example, the clearance of the vertical
direction between the horizontal element of the loop-conductive element 58c and the
continuous-horizontal conductor 4d is maintained by 10 mm.
[0078] Fig. 13 shows the measurement result of the average sensitivity in the glass antenna
for vehicle of the second comparative example shown in Fig. 12, and of the respective
embodiments shown in Fig. 10 and Fig. 11. Moreover, the numeric measurement result
corresponding to Fig. 13 is shown in Table 6 (the unit is dBi). In addition, each
measurement result representing the ratio of the signal-receiving sensitivity based
on the measurement result of the mean value (the average of signal-receiving sensitivity)
received with the dipole antenna is shown in Table 6, where the mean value is value
averaged by 180 degrees over the horizontal direction of the digital TV antenna in
the outside direction of the vehicle (i.e., the signal-receiving sensitivity measured
from the sideward of the vehicle to the backward thereof).
[0079]
[Table 6]
(dBi) |
Average Sensitivity |
2nd Comparative Example (Fig. 12) |
5th Embodiment (Fig. 10) |
6th Embodiment (Fig. 11) |
Mean Value |
-8.3 |
-7.1 |
-6.2 |
Min. Value |
-11.2 |
-10.4 |
-9.6 |
Max. Value |
-6.8 |
-5.5 |
-4.5 |
[0080] It should be understood from Fig. 13 and Table 6 that the sensitivity characteristic
of the digital TV antenna of each glass antenna in the fifth embodiment (Fig. 10)
and the sixth embodiment (Fig. 11) is improved, compared with the second comparative
example (Fig. 12).
[0081] Moreover, it should be noted that each arrangement of the fifth embodiment and the
sixth embodiment enables to prevent the deterioration of the sensitivity characteristic
of the AM antenna, in similar with the above third and fourth embodiments.
[0082] Therefore, according to the glass antenna for vehicle in the fifth and sixth embodiments,
providing of the discontinuous region into the AM antenna 4 also enables to change
the directivity of the digital TV antenna 18 into the direction vertical to the surface
of the rear-window glass, and to control said directivity into the direction of the
desired wave of the digital TV antenna.
[0083] Then, a glass antenna for vehicle of a seventh embodiment in accordance with the
invention is described.
(SEVENTH EMBODIMENT)
[0084] Fig. 14 is a schematic diagram of a glass antenna for vehicle in a seventh embodiment
according to the invention. The glass antenna for vehicle of the seventh embodiment
comprises a digital TV antenna 28 for twin loop antenna, and is similar with that
of the above described fourth embodiment, other than the configuration of the digital
TV antenna, and thus its similar description is omitted. In this embodiment, it is
noted that the digital TV antenna is not limited to the type of twin loop antenna,
and may be applied to the type of single loop antenna. The horizontal elements in
the digital TV antenna 28 of the seventh embodiment are composed of conductor elements
28c and 28d.
[0085] As shown in Fig. 14, the digital TV antenna 28 for twin loop antenna includes the
horizontal elements being composed of the conductor elements 28c and 28d. The clearance
of the vertical direction, y, between theses horizontal elements and the continuous-horizontal
conductor 4d is maintained by 90 mm. Moreover, the clearance of the horizontal direction,
x, between each horizontal element (the conductor element 28c or 28d) of the twin
loop-conductive element 28 and the discontinuous-horizontal conductor 4c is provided
by 40 mm, as the distance along the surface of the window glass for vehicle.
[0086] Then, a glass antenna for vehicle of an eighth embodiment in accordance with the
invention is described.
(EIGHTH EMBODIMENT)
[0087] Fig. 15 is a schematic diagram of a glass antenna for vehicle in an eighth embodiment
according to the invention. The arrangement of the glass antenna for vehicle of the
eighth embodiment is similar with that of the seventh embodiment, other than the configuration
of the AM antenna 4, and thus its similar description is omitted. As shown in Fig.
15, the AM antenna 4 of the eighth embodiment includes in the discontinuous region
at least one gamma (Γ)-shaped AM antenna element which is composed of a vertical conductor
4h and a partial, horizontal conductor 4j (in this figure, four gamma-shaped AM antenna
elements). Thus, the signal-receiving sensitivity of the AM antenna 4 can be improved
with little influence for the signal-receiving sensitivity of the digital TV antenna
28 if the AM antenna 4 is arranged by providing the discontinuous region 4g with the
gamma-shaped AM antenna elements, while this will be clear from the later description.
This means that the clearance of the vertical direction, y, between each horizontal
element (the conductor element 28c or 28d) of the twin loop-conductive element 28
and the continuous-horizontal conductor 4d may be defined.
[0088] Besides, in the eighth embodiment shown in Fig. 15, the clearance of the vertical
direction, y, between each horizontal element (the conductor element 28c or 28d) of
the twin loop-conductive element 28 and the continuous-horizontal conductor 4d is
maintained by 90 mm. Moreover, the clearance of the horizontal direction, x, between
each horizontal element (the conductor element 28c or 28d) of the twin loop-conductive
element 28 and the discontinuous-horizontal conductor 4c is provided by 25 mm, as
the distance along the surface of the window glass for vehicle.
[0089] Then, a glass antenna for vehicle of a ninth embodiment in accordance with the invention
is described.
(NINTH EMBODIMENT)
[0090] Fig. 16 is a schematic diagram of a glass antenna for vehicle in a ninth embodiment
according to the invention. The arrangement of the glass antenna for vehicle of the
ninth embodiment is similar with that of the eighth embodiment, other than the configuration
of the AM antenna 4, and thus its similar description is omitted. As shown in Fig.
16, the AM antenna 4 of the ninth embodiment includes in the discontinuous region
4g an AM antenna element of continuous meander-shape (hereinafter, it is referred
to as a meander-shaped AM antenna element) which is composed of a vertical conductor
4h and a partial, horizontal conductor 4k. Thus, the signal-receiving sensitivity
of the AM antenna 4 can be improved with little influence for the signal-receiving
sensitivity of the digital TV antenna 28 if the AM antenna 4 is arranged by providing
the discontinuous region 4g with the meander-shaped AM antenna elements, while this
will be clear from the later description. This means that the clearance of the vertical
direction, y, between each horizontal element (the conductor element 28c or 28d) of
the twin loop-conductive element 28 and the FM antenna 5 or the defogger 3 may be
defined.
[0091] Besides, in the ninth embodiment shown in Fig. 16, the clearance of the vertical
direction, y, between each horizontal element (the conductor element 28c or 28d) of
the twin loop-conductive element 28 and the FM antenna 5 is maintained by 120 mm.
Moreover, there is provided the clearance of the horizontal direction, x, between
each horizontal element (the conductor element 28c or 28d) of the twin loop-conductive
element 28 and the discontinuous-horizontal conductor 4c is provided by 25 mm, as
the distance along the surface of the window glass for vehicle.
[0092] Then, a glass antenna for vehicle of a tenth embodiment in accordance with the invention
is described.
(TENTH EMBODIMENT)
[0093] Fig. 17 is a schematic diagram of a glass antenna for vehicle in a tenth embodiment
according to the invention. The arrangement of the glass antenna for vehicle of the
tenth embodiment is another aspect of the ninth embodiment in which a meander-shaped
AM antenna element, which is composed of a vertical conductor 4h and a partial, horizontal
conductor 4k, is provided in the discontinuous region 4g. In the tenth embodiment
shown in Fig. 17, the clearance of the vertical direction, y, between each horizontal
element (the conductor element 28c or 28d) of the twin loop-conductive element 28
and the continuous-horizontal conductor 4d is maintained by 120 mm. Moreover, the
clearance of the horizontal direction, x, between each horizontal element (the conductor
element 28c or 28d) of the twin loop-conductive element 28 and the discontinuous-horizontal
conductor 4c is provided by 55 mm, as the distance along the surface of the window
glass for vehicle.
[0094] Then, a third comparative example of a glass antenna for vehicle is described hereinafter
to make the effect of the seventh to tenth embodiments clearer. The same numerals
are fixed to similar components or elements in this description.
(THIRD COMPARATIVE EXAMPLE)
[0095] Fig. 18 shows a schematic diagram of a glass antenna for vehicle in a third comparative
example. The composition of the glass antenna for vehicle of the third comparative
example shown in Fig. 18 is different from these glass antennas for vehicle of the
seventh to tenth embodiments, since the AM antenna 4 does not have the discontinuous
region 4g.
[0096] As shown in Fig. 18 of the glass antenna for vehicle in the third comparative example,
the clearance of the vertical direction, y, between the twin loop-conductive element
28 and the continuous-horizontal conductor 4d is maintained by 30 mm.
[0097] Fig. 19 shows a comparative graph of the measurement result of the sensitivity characteristic
of the digital TV antenna in the glass antenna for vehicle of the third comparative
example shown in Fig. 18 and of the respective seventh to the tenth embodiments shown
in Figs. 14-17. Moreover, the numeric measurement result corresponding to Fig. 19
is shown in Table 7 (the unit is dBi). In addition, the mean value, the minimum value,
and the maximum value of the sensitivity characteristic corresponding to Table 7 are
shown in Table 8 (the unit is dBi). In addition, each measurement result representing
the ratio of the signal-receiving sensitivity based on the measurement result of the
mean value (the average of signal-receiving sensitivity) received with the dipole
antenna is shown in Fig. 19, in Table 7, and in Table 8, where the mean value is value
averaged by 180 degrees over the horizontal direction of the digital TV antenna in
the outside direction of the vehicle (i.e., the signal-receiving sensitivity measured
from the sideward of the vehicle to the backward thereof).
[0098]
[Table 7]
(dBi) |
Frequency |
Average Sensitivity |
[MHz] |
3rd Comparative Example (Fig. 18) |
7th Embodiment (Fig. 14) |
8th Embodiment (Fig. 15) |
9th Embodiment (Fig. 16) |
10th Embodiment (Fig. 17) |
470 |
-12. 6 |
-10. 2 |
-10. 1 |
-10. 1 |
-10. 0 |
480 |
-11. 8 |
-9. 5 |
-9. 7 |
-9. 8 |
-9. 7 |
490 |
-11. 0 |
-9. 2 |
-9. 1 |
-9. 3 |
-9. 2 |
500 |
-10. 5 |
-9. 3 |
-8. 9 |
-8. 9 |
-8. 8 |
510 |
-9. 2 |
-8. 7 |
-8. 5 |
-8. 2 |
-8. 1 |
520 |
-8. 4 |
-9. 2 |
-8. 5 |
-8. 3 |
-8. 0 |
530 |
-8. 3 |
-10. 1 |
-9. 8 |
-9. 1 |
-8. 5 |
540 |
-8. 8 |
-8. 5 |
-9. 5 |
-9. 7 |
-9. 3 |
550 |
-9. 0 |
-8. 3 |
-9. 0 |
-8. 8 |
-8. 8 |
560 |
-8. 5 |
-8. 1 |
-8. 2 |
-7. 7 |
-7. 8 |
570 |
-8. 4 |
-9. 1 |
-8. 3 |
-7. 4 |
-7. 4 |
580 |
-8. 4 |
-8. 3 |
-7. 6 |
-7. 0 |
-7. 0 |
590 |
-8. 4 |
-7. 5 |
-6. 9 |
-6. 6 |
-6. 5 |
600 |
-8. 4 |
-6. 8 |
-6. 2 |
-6. 2 |
-6. 1 |
610 |
-9. 1 |
-6. 4 |
-6. 4 |
-6. 4 |
-6. 0 |
620 |
-9. 7 |
-6. 0 |
-6. 6 |
-6. 6 |
-6. 3 |
630 |
-10. 3 |
-6. 8 |
-7. 0 |
-7. 0 |
-6. 9 |
640 |
-9. 3 |
-6. 9 |
-7. 0 |
-6. 8 |
-7. 0 |
650 |
-9. 9 |
-7. 4 |
-7. 5 |
-7. 5 |
-7. 3 |
660 |
-9. 9 |
-7. 0 |
-6. 9 |
-6. 8 |
-6. 7 |
670 |
-9. 0 |
-6. 8 |
-7. 0 |
-7. 0 |
-6. 9 |
680 |
-9. 5 |
-6. 8 |
-7. 4 |
-7. 3 |
-7. 2 |
690 |
-10. 5 |
-6. 5 |
-7. 2 |
-7. 3 |
-7. 2 |
700 |
-10. 4 |
-6. 5 |
-7. 0 |
-7. 2 |
-7. 1 |
710 |
-9. 7 |
-6. 1 |
-6. 3 |
-6. 4 |
-6. 3 |
720 |
-10. 0 |
-6. 4 |
-6. 5 |
-6. 6 |
-6. 5 |
730 |
-9. 8 |
-6. 9 |
-6. 9 |
-7. 1 |
-6. 8 |
740 |
-8. 5 |
-7. 1 |
-6. 8 |
-6. 8 |
-6. 7 |
750 |
-7. 6 |
-6. 4 |
-6. 3 |
-6. 2 |
-6. 1 |
760 |
-6. 9 |
-5. 5 |
-5. 3 |
-5. 3 |
-5. 2 |
770 |
-6. 0 |
-4. 8 |
-4. 7 |
-4. 8 |
-4. 6 |
[0099]
[Table 8]
(dBi) |
Average Sensitivity |
3rd Embodiment (Fig. 18) |
7th Embodiment (Fig. 14) |
8th Embodiment (Fig. 15) |
9th Embodiment (Fig. 16) |
10th Embodiment (Fig. 17) |
Mean Value |
-9. 3 |
-7. 5 |
-7. 5 |
-7. 4 |
-7. 3 |
Min. Value |
-12. 6 |
-10. 2 |
-10. 1 |
-10. 1 |
-10. 0 |
Max. Value |
-6. 0 |
-4. 8 |
-4. 7 |
-4. 8 |
-4. 6 |
[0100] It should be understood from Fig. 19, and Table 8 that the sensitivity characteristic
of the digital TV antenna is improved by providing the AM antenna 4 with the discontinuous
region 4g.
[0101] In particular, it should be understood from Table 8 that the average sensitivity
of the digital TV antenna of each glass antenna of the seventh to tenth embodiments
shown in Figs. 14-17 is improved by 1.8 dB, 1.8 dB, 1.9 dB, and 2.0 dB respectively,
compared with the glass antenna for vehicle shown in Fig. 18 (the third comparative
example).
[0102] Then, the sensitivity characteristic of the AM antenna by providing the AM antenna
with the discontinuous region 4g is described.
[0103] Table 9 shows comparative values of the measurement result of the sensitivity characteristic
of the digital TV antenna in each glass antenna for vehicle of the third comparative
example shown in Fig. 18 and of the seventh to tenth embodiments shown in Figs. 14-17,
respectively (the unit is dBµV).
[0104]
[Table 9]
(dB µV) |
|
594KHz |
954KHz |
1242KHz |
1458KHz |
Mean Value |
Min. Value |
3rd Embodiment (Fig. 18) |
31. 2 |
30. 5 |
31. 3 |
33. 6 |
31. 7 |
30. 5 |
7th Embodiment (Fig. 14) |
31. 0 |
30. 2 |
31. 1 |
33. 3 |
31. 4 |
30. 2 |
8th Embodiment (Fig. 15) |
30. 9 |
30. 1 |
31. 0 |
33. 2 |
31. 3 |
30. 1 |
9th Embodiment (Fig. 16) |
30. 8 |
30. 0 |
31. 0 |
33. 2 |
31. 3 |
30. 0 |
10th Embodiment (Fig. 17) |
30. 7 |
30. 0 |
31. 0 |
33. 2 |
31. 2 |
30. 0 |
[0105] As described in each glass antenna for vehicle of the seventh to tenth embodiments
shown in Figs. 14-17, it should be understood from Table 9 that the signal-receiving
sensitivity of the AM antenna significantly equal to the third comparative example
(Fig. 18) is obtained by providing the gamma-shaped AM antenna element or the meander-shaped
AM antenna element into the discontinuous region 4g of the AM antenna 4.
[0106] Therefore, it should be understood that the antenna characteristic for digital TV
broadcasting is improved in each glass antenna for vehicle of the seventh to tenth
embodiments shown in Figs. 14-17, without decreasing the signal-receiving sensitivity
of the AM antenna 4.
[0107] Therefore, in each glass antenna for vehicle of the seventh to tenth embodiments,
providing of the discontinuous region into the AM antenna 4 also enables to change
the directivity of the digital TV antenna into the direction vertical to the surface
of the rear-window glass, and to control said directivity into the direction of the
desired wave of the digital TV antenna.
[0108] The invention is not limited to these embodiments shown in drawings, while the examples
of the meander-shaped AM antenna elements provided into the discontinuous region 4g
are shown in Figs. 16 and 17 of the glass antenna for vehicle of the above the ninth
and tenth embodiments. For example, the meander-shaped AM antenna elements shown in
Figs. 16 and 17 may be not only the rectangular-shaped bending wire but also the round
corner-shaped bending wire or the meander-shaped wire with respect to entirely sinusoidal-shape
of the meander-shaped AM antenna.
[0109] Moreover, since the clearance of the vertical direction, y, is defined by the part
of the antenna element extended in parallel with the digital TV antenna 28 as visibly
described, the AM antenna elements each of which is composed of a vertical conductor
4h and a partial, horizontal conductor 4j or 4k in the discontinuous region 4g may
be provided individually (Figs. 14-17). Moreover, the shape and the size of the AM
antenna element, and the distance between said AM antenna elements may be formed by
any manner.
[0110] Then, glass antennas for vehicle of other embodiments in accordance with the invention
are described.
(OTHER EMBODIMENTS)
[0111] As shown in Fig. 20, this glass antenna for vehicle may comprise a digital TV antenna
38 of the dipole antenna type. The horizontal element of the digital TV antenna 38
in this embodiment is composed of conductor elements 38c and 38d.
[0112] As shown in Fig. 21, this glass antenna for vehicle may comprise a digital TV antenna
48 of the monopole antenna type with parasitic elements 41 a and 41b to improve the
sensitivity characteristic thereof. Besides, the digital TV antenna 48 may be either
of parasitic elements 41a and 41b. The horizontal element of the digital TV antenna
48 in this embodiment is composed of conductor elements 41 a, 4 1 b and 4 1 c which
are capacitive-coupled mutually.
[0113] As shown in Fig. 22, this glass antenna for vehicle may comprise digital TV antennas
18L and 18R arranged at both ends of the window glass for vehicle. Besides, the plurality
of the digital TV antennas may be arranged at not only the rear-window glass but also
the front-window glass or the side of the window glass of the vehicle for diversity
combining of the received signal from the respective digital TV antennas.
[0114] Moreover, The shape of the AM antenna may be transformed in arbitrary antenna pattern,
and the connection between the discontinuous-horizontal conductor 4c and the continuous-horizontal
conductor 4d in the AM antenna may be arbitrarily formed. For example, the opposed
edge to the feeding point of the AM antenna 4 shown in Figs. 3-6 may be electrically
connected with conductive elements, while each AM antenna 4 shown in Figs. 3-6 has
the opposed edge of open-end as antenna pattern. Alternatively, while the edge of
this discontinuous-horizontal conductor 4c is connected to the continuous-horizontal
conductor 4d, the edge of the discontinuous-horizontal conductor 4c may be the edge
of open-end as antenna pattern.
[0115] Moreover, the AM antenna may include a shorting-wire 4f for connecting between the
plural horizontal conductors respectively, and the location of the shorting-wire may
be arbitrarily fixed.
[0116] Besides, the distance between the heat wires 3e for defogging or the main body of
the vehicle and the AM antenna is preferably 30 mm or more, to prevent the decrease
of the signal-receiving sensitivity of the AM antenna because of capacitive-coupling
into the heat wires 3e or the main body.
[0117] It is noted for those skilled in the art to be able to achieve the invention by variously
combining the above embodiments other than the configuration of the embodiments described
in the above.
[0118] For example, the area of the AM antenna may be the same by extending or adding the
horizontal conductor of the AM antenna to an extent that the horizontal conductor
of the AM antenna located under the digital TV antenna is deleted.
[0119] In addition, the distance of x
1 and x
2 need not be limited to 0 mm or more, while the distance of x
1 and x
2 in case of 0 mm or more is described in the above embodiments. That is, the clearance
of the horizontal direction of the discontinuous region 4g may be shorter than the
length of the horizontal element 18c of the digital TV antenna 18. Providing of the
discontinuous region 4g into the AM antenna 4 improves the sensitivity characteristic
of the digital TV antenna with respect to the first comparative example (Fig. 7).
This should be understood on the basis of the result in the above described Table
4.
[0120] It should be understood that a lot of variations and modifications is able to be
implemented by those skilled in the art in the spirit or scope of the present invention,
while the specific examples are described in the above-described embodiments. For
example, the digital TV antenna may be arranged under the defogger or the AM antenna,
while there is described the arrangement of the digital TV antenna provided over the
defogger or the AM antenna. Accordingly, the invention is not to be considered as
limited by the foregoing description but is only limited by the scope of the appended
claims.
INDUSTRIAL APPLICABILITY
[0121] According to the invention, a glass antenna for vehicle, which comprises an antenna
for digital terrestrial TV broadcasting and an AM antenna, may be provided with extremely
high sensitivity, and thus it is useful to a motor vehicle comprising such a glass
antenna.