JPH10107528A - Glass antenna system for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high reception sensitivity without a preamplifier by placing an antenna conductor and an earth conductor in parallel, connecting electrically a parallel connection circuit of a 1st coil and a capacitor between the antenna conductor and a receiver and causing 1st resonance with a stray capacitance between the 1st coil and a cable. SOLUTION: In the case of receiving a low reception frequency band, an inductance of a 1st coil 3 and a stray capacitance cause series resonance (1st resonance). An antenna conductor 1 has a stray capacitance, and an inductance of a 2nd coil 8 and a stray capacitance mainly cause apparent parallel resonance (2nd resonance). The reception sensitivity at a desired reception frequency band is improved by the two resonance phenomena and made flat. Furthermore, a capacitance of a capacitor 7 shows a low impedance at a high reception frequency band and indicates a high impedance at a low reception frequency band. Thus, a reception signal at a high reception frequency band induced in the antenna conductor 1 is fed to the receiver via the capacitor 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass antenna device for a vehicle which is suitable for receiving AM broadcast, FM broadcast, television broadcast and the like.

[0002]

2. Description of the Related Art Conventionally, in a glass antenna for receiving an AM broadcasting band and an FM broadcasting band, the antenna conductor provided on a window glass plate has a small area, so that the receiving sensitivity of the antenna is poor and the shortage of the receiving sensitivity is compensated. For this reason, a preamplifier is inserted and connected to a suitable portion of a feed line between a feed point of an antenna conductor and a receiver. However, as a result of inserting the preamplifier, there is a problem that waveform distortion or cross modulation occurs in a strong electric field, and the noise is amplified as it is. In addition, since a preamplifier must be provided separately from the receiver, there is a problem that productivity is low.

As shown in FIG. 5, an antenna conductor 92 and a feed point 92a are provided on a side window glass plate 11 at the rear of the automobile.
There is known a glass antenna device for a vehicle provided with the following.
In the prior art shown in FIG. 5, a preamplifier was required because the receiving sensitivity was insufficient. In addition, since the conductor pattern of the antenna conductor 92 is complicated, it takes a long time to design the shape of the conductor pattern to obtain appropriate reception characteristics, and productivity is poor.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a window having a simple conductor pattern, which does not use a preamplifier, has a performance equal to or higher than that of the prior art, and has a small area where an antenna conductor can be provided. Another object of the present invention is to provide a glass antenna device for a vehicle that can receive a signal with high sensitivity even with a glass plate.

[0005]

The present invention comprises an antenna conductor provided on a window glass plate of a vehicle, a ground conductor, a feed point provided on the antenna conductor, and a ground point provided on the ground conductor. The conductor and the ground conductor are substantially parallel, and the antenna conductor enables reception of both the low reception frequency band and the high reception frequency band, and a first coil, a capacitor, and a capacitor are provided between the antenna conductor and the receiver. Are electrically connected in parallel with each other, so that the inductance value of the first coil has a low impedance at least in a low reception frequency band, and the capacitor has a low impedance in a high reception frequency band. The capacitance value is such that the impedance becomes high in the frequency band, and the capacitance value includes the inductance of the first coil and the stray capacitance of the cable. And causes the first resonance to occur, so that the resonance frequency of the first resonance exists at a frequency lower than the high reception frequency band, and the end of the capacitor opposite to the antenna conductor side and the receiver side Are electrically connected by a cable to provide a glass antenna device for a vehicle.

The width of the ground conductor is 0.2 to 10 mm.
And the glass antenna device for a vehicle in which the distance between the antenna conductor and the ground conductor is in the range of 1 to 100 mm.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a configuration diagram of a typical example of a glass antenna device for a vehicle according to the present invention, and assumes reception in two reception frequency bands, a low reception frequency band and a high reception frequency band.

In FIG. 1, reference numeral 11 denotes a window glass on the rear side of an automobile, 1 denotes an antenna conductor, 3 denotes a first coil,
7 is a bypass capacitor for a high reception frequency band, 8 is a second coil provided as needed, 13 is a ground conductor,
Reference numeral 1a denotes a feed point for connecting the antenna conductor 1 to an inner conductor of a coaxial cable (not shown), and 13a denotes a ground conductor 3.
Is a third coil 18 provided as needed. In the drawings other than FIG. 1, the names of the same numbers and the same reference numerals as those of FIG. 1 are the same as those of FIG. 1.

FIG. 2 shows an equivalent circuit diagram of FIG. In FIG. 2, E _L is the voltage power supply of the antenna conductor 1, C _L0 is the effective capacitance of the antenna conductor 1, C _L1 is the stray capacitance (ineffective capacitance) of the antenna conductor 1, and C _H1 is the stray capacitance (not shown) of the cable (not shown). Invalid capacity).

Here, the cable refers to a cable that connects an end of the bypass capacitor on the receiver side to a receiver (not shown). The stray capacitance is the capacitance (electric c
apacity). In the drawings other than FIG. 2, the names of the same numbers and the same reference numerals as those of FIG. 2 are the same as those of FIG. 2.

The ground point 13a is normally connected to the vehicle body ground. When a coaxial cable is used as the cable, an outer conductor of the coaxial cable is usually connected to the ground point 13a.

In the high reception frequency band, it is preferable that the first coil 3 has a high impedance for high reception frequency band reception. However, in the high reception frequency band, the first coil 3 can be used even if it does not have high impedance.

The low impedance refers to an impedance within a range in which a received signal of the antenna conductor 1 in a low reception frequency band easily flows to the receiver side, and is usually five times or less the input impedance of the receiver side. The input impedance on the receiver side usually means the input impedance of the receiver. However, when an impedance converter is connected between the input of the receiver and the antenna, it refers to the input impedance of the impedance converter.

The term "high impedance" refers to an impedance within a range in which a reception signal in a low reception frequency band of the antenna conductor 1 is difficult to flow to the receiver, and is generally more than five times the input impedance of the receiver.

When the low reception frequency band is AM broadcasting, A
The input impedance of the receiver at the time of receiving the M broadcast is usually 1 to 10 kΩ. Therefore, for example, when the input impedance on the receiver side is 5 kΩ, 25 kΩ
Ω or less has low impedance, and more than 25 kΩ has high impedance.

When the high receiving frequency band is FM broadcasting, the input impedance of the receiver at the time of receiving FM broadcasting is usually 50 or 75Ω. So, for example,
If the input impedance on the receiver side is 50Ω, 250Ω or less becomes low impedance and 250Ω
Super becomes high impedance.

In the case of reception in a low reception frequency band, a reception signal of the antenna conductor 1 is transmitted to the first coil 3, and the reception signal is transmitted to a receiver. In this case, the first
A series resonance (first resonance) is caused by the inductance of the coil 3 and the stray capacitance C _H1 . In short, the first resonance is caused between the first coil 3 and the first other element. Here, the first other element is not limited to the stray capacitance C _H1, but is an element that affects the first resonance, and is an inductance component artificially or non-artificially added to the circuit of FIG. It includes a capacitance component, a resistance component, and the like. For example, there is an example in which a capacitor is connected in parallel with the stray capacitance C _H1 .

Due to the first resonance which is the series resonance, the reactance (series resonance reactance) of the first coil 3 and the stray capacitance C _H1 connected in series and the stray capacitance C _L1 are viewed from the antenna conductor 1 side. In this case, parallel resonance occurs.

By this parallel resonance, the receiving sensitivity in a desired receiving frequency band can be improved. For the first resonance, it is necessary that the resonance frequency exists at a frequency lower than the high reception frequency band. In the case where the first resonance is caused, the reception sensitivity in the entire low reception frequency band is usually smaller than the case where the first resonance is not caused.
It is improved by about 5 dB or more.

The resonance frequency of the parallel resonance preferably exists in a low reception frequency band. When it is present, the reception sensitivity in the entire low reception frequency band is lower than when it does not exist,
Usually, it is improved by about 10 dB or more.

The first resonance is slightly affected by the stray capacitance of the wiring around the antenna conductor 1. For example, the first
And the stray capacitance of wiring such as the second coil 8 and the second coil 8.

In the present invention, the antenna conductor 1 has a stray capacitance C
Has _L1, it is preferable to inductance and mainly apparently parallel resonance with the stray capacitance C _L1 of the second coil 8 (second resonance).

In short, the second resonance is caused by the second coil 8 and the second other element. Here, the second other element is not limited to the stray capacitance C _L1, but is an element affecting the second resonance, and an inductance component artificially or non-artificially added to the circuit of FIG. It includes a capacitance component, a resistance component, and the like. For example, there is an example in which a capacitor is connected in parallel with the stray capacitance C _L1 .

In order to cause this second resonance, the second resonance
Even if the inductance value of the coil 8 and the value of the second other element are set, the second resonance (hereinafter, apparently the second resonance) does not actually occur, and is shown in FIG. In the system of the entire circuit, two resonances different from the second resonance (accompanying resonances of the second resonance) occur. This incident resonance causes the antenna conductor 1
When viewed from the side, it has a strong parallel resonance property.

By these two resonances, the receiving sensitivity in a desired receiving frequency band can be improved and the receiving frequency can be flattened. When the incidental resonance of the second resonance is caused to occur, the receiving sensitivity in the entire low receiving frequency band is improved by about 5 dB or more as compared with the case where the incidental resonance is not caused.

The capacitor 7 has such a capacitance value that it has a low impedance in a high reception frequency band and a high impedance in a low reception frequency band. Therefore, the reception signal of the high reception frequency band excited by the antenna conductor 1 is sent to the receiver via the capacitor 7. Capacitor 7
The capacitance value is usually about 1 to 1000 pF. For example, when the low reception frequency band is the AM broadcast band and the high reception frequency band is the FM broadcast band, the capacitance value of the capacitor 7 is preferably in the range of 5.0 to 33 pF.

FIG. 3 is a plan view of a typical example of the pattern of the antenna conductor 1 according to the present invention. 3, 4 the vehicle body opening, L ₁ is the antenna conductor 1 length, L ₂ is substantially vertical length of the grounding conductor 13, the distance d ₁ is the antenna conductor 1 and ground conductor 13, d ₂ is The shortest distance between the antenna conductor 1 and the vehicle body opening 4.

In the present invention, the antenna conductor 1, the feeding point 1
a, the ground conductor 13 and the ground point 13a
1 is provided. Further, as shown in FIG. 3, the antenna conductor 1 and the ground conductor 13 are provided substantially in parallel, and by providing a simple pattern on the window glass plate, a radio signal can be efficiently received. The power supply point 1a is preferably provided near the ground point 13a, and the distance between the two is preferably within 50 mm, more preferably within 30 mm.

The shape of the ground conductor 13 is as follows.
In order to make the distance d ₁ between the antenna conductor 1 and the ground conductor 13 constant and to easily determine the pattern of the antenna conductor 1 and the ground conductor 13 for improving the reception characteristics or adjusting the reception characteristics, a substantially band shape is preferable. However, the present invention is not limited to this, and the shape of the ground conductor 13 is substantially elliptical, substantially circular, for example, substantially triangular such as a right triangle, substantially square, substantially polygonal, or
It may be substantially V-shaped. When the antenna conductor 1 and the ground conductor 13 are provided at the corners of the window glass plate, the ground conductor 1
The shape of 3 may be preferably a substantially elliptical shape, a substantially circular shape, a substantially right triangle, or the like. The ground conductor 13 and the ground point 13
a may be integrated.

The shape of the antenna conductor 1 may be generally a straight line, a substantially curved line, a substantially V shape, or the like, and the line width of the antenna conductor 1 is usually 0.2 to 5 mm. Is preferred.

The antenna conductor 1 and the ground conductor 13 need to be substantially parallel to each other at a predetermined interval. However,
If most of the antenna conductor 1 and the ground conductor 13 are substantially parallel, even if some of them are not substantially parallel, they can be used.

The distance d between the antenna conductor 1 and the ground conductor 13
₁ is preferably ₁ to 100 mm. When it is within this range, the reception sensitivity in a high-frequency band such as an FM broadcast band is usually improved by about 2 dB or more as compared with the case outside this range.

The distance d ₁ is preferably 3 to 70 mm. When the distance d ₁ is within this range, the reception sensitivity in a high frequency band of 10 MHz or more, such as the FM broadcast band, is usually smaller than that outside this range. It is improved by about 1.5 dB or more.

The shortest distance d ₂ between the antenna conductor 1 and the vehicle body opening 4 is preferably 5 to 300 mm. In the case of being within this range, the reception sensitivity in a high frequency band of 10 MHz or more, such as the FM broadcasting band, is usually 0.1 in comparison with the case of being out of this range.
It is improved by about 5 dB or more. The shortest distance d ₂ is 10
It is more preferable that the distance be within 200 mm.
The reception sensitivity in a high frequency band of 0 MHz or more is usually improved by about 1.0 dB or more.

Regarding the positions of the antenna conductor 1 and the ground conductor 13, it is preferable that the ground conductor 13 is disposed between the vehicle body opening 4 and the antenna conductor 1. In this case, the reception sensitivity in a high frequency band of 10 MHz or more such as an FM broadcasting band is usually 1.0 d compared to the case where the antenna conductor 1 is provided between the vehicle body opening 4 and the ground conductor 13.
B or more is improved. Here, the vehicle body opening 4 is an opening of the vehicle body into which the window glass plate is to be fitted and which should serve as a vehicle body ground, and is made of a conductive material such as metal.

When the length L ₁ of the antenna conductor 1 is λ, the wavelength of the desired reception center frequency is λ, the glass shortening rate is K, the maximum reception frequency wavelength is λ _H , and the minimum reception frequency wavelength is λ _L , effect, when taking into account the influence of the glass shape determined experimentally, it is preferable that _{(λ H · K / 8)} ~λ L · K. When it is within this range, the reception sensitivity in a high-frequency band of 10 MHz or more, such as the FM broadcast band, is usually improved by about 2 dB or more as compared with the case outside this range. The glass shortening rate K is usually 0.64. A more preferable range of the length L ₁ of the antenna conductor 1 is (λ _H · K / 4) to (λ
_L · K / 2).

[0037] Similarly, the length L ₂ of the grounding conductor 13 is preferably _{(λ H · K / 20)} ~ (λ L · K / 2). When it is within this range, the reception sensitivity in a high frequency band of 10 MHz or more, such as the FM broadcast band, is usually improved by about 1.0 dB or more as compared with the case outside this range.

The width of the ground conductor 13 is 0.2 to 10
mm. When it is within this range, the reception sensitivity in a high frequency band of 10 MHz or more, such as the FM broadcast band, is usually improved by about 1.0 dB or more as compared with the case outside this range.

The width of the ground conductor 13 is 0.2 to 3 m.
m is more preferable, and within this range,
10MHz of FM broadcast band etc.
The reception sensitivity in the high frequency band described above is usually improved by about 0.5 dB or more.

In FIG. 1, the feed point 1a and the ground point 13a are
Although provided at the upper right of the side window glass plate 11, it is not limited to this location, and may be provided at any position of the window glass plate. It may be.

The glass antenna of the present invention is not limited to AM and FM radio broadcasting bands, but can be applied to television VHF bands, television UHF bands, telephones, etc., and has an antenna conductor and a ground conductor provided on a window glass plate. Is not limited.

In the present invention, the window glass plate provided with the antenna conductor is not limited to the side window glass plate.
It may be a rear window glass plate, a front window glass plate, a roof window glass plate, or the like.

The antenna conductor and the ground conductor are usually manufactured by printing and baking a conductive metal-containing paste such as a conductive silver paste on the inner surface of the window glass plate. The method is not limited, and a conductive linear body or foil-like body such as a copper wire may be formed on the inside or outside surface of the window glass plate, or may be provided inside the window glass plate. Further, at least one of the antenna conductor and the ground conductor may be made of a transparent conductive material.

Further, in the present invention, the numbers of antenna conductors and ground conductors provided on the vehicle are not limited, and the glass antennas of the present invention, the glass antenna of the present invention, and other antennas such as a pole antenna may be used. Antenna and / or
Alternatively, diversity reception may be performed with another glass antenna.

FIG. 4 is a circuit diagram showing an application example of the resonance circuit according to the present invention. 4, reference numerals 21 and 22 denote damping resistors, 61 denotes a first high-frequency coil, 62 denotes a second high-frequency coil, 63 denotes a third high-frequency coil, and 71 denotes a capacitor. The first high-frequency coil 61, the second high-frequency coil 62, and the third high-frequency coil 63 are provided as necessary, and have a function of preventing a reception signal from leaking to the vehicle body ground.

As a combination of the first high-frequency coil 61, the second high-frequency coil 62, and the third high-frequency coil 63, it is preferable that only the third high-frequency coil 63 is provided. High frequency coil 6
More preferably, 2 is provided. First high frequency coil 6
When the first and second high-frequency coils 62 are provided, the reception characteristics are hardly affected whether or not the third high-frequency coil 63 is provided. However, productivity is better when the third high frequency coil 63 is not provided than when it is provided.

When only the third high-frequency coil 63 is provided, the reception sensitivity in the high reception frequency band is usually 2d compared to the case where no high-frequency coils 61, 62, 63 are provided.
B or more. Also, the first high-frequency coil 61 and the second
When the high frequency coil 62 is provided, the high frequency coil 6
Compared with the case where 1, 62 and 63 are not provided at all, the reception sensitivity in the high reception frequency band is usually improved by 3 dB or more.

FIG. 4 shows a case where a first high-frequency coil 61 and a second high-frequency coil 62 are provided,
In the case of reception in the low reception frequency band, since the first high-frequency coil 61 and the second high-frequency coil 62 have low impedance together with the first coil 3, the antenna conductor 1 and the receiver side are connected. In the case where the third high-frequency coil 63 is provided, and in the case of reception in a low reception frequency band, the third high-frequency coil 63 has a low impedance, and the second resonance occurs. The high frequency coils 61, 62, 63 are usually
About 0.1 to 100 μH is used.

When the high receiving frequency band is 10 MHz or higher, the high frequency coils 61, 62, 63 have inductive impedance and high impedance at least in the high receiving frequency band. Or the second
When the coil 8 of the high frequency coil 6 has a high reception frequency band, the self-resonant frequency is usually low and the inductance is lost.
1, 62 and 63 act on behalf of this.

If the first coil 3 or the second coil 8 can make a wide frequency band from a low reception frequency band to a high reception frequency band a high impedance, the high frequency coils 61, 62,
63 is unnecessary and can be omitted.

In some cases, lead wires of an appropriate length can be used as the high-frequency coils 61, 62, 63. But,
Usually, a solenoid using no magnetic core or a coil using a magnetic core is used.

The antenna conductor 1 functions as an antenna conductor for a low reception frequency band and a high reception frequency band.

The capacitor 7 has a capacitance value such that it has a low impedance in a high reception frequency band and has a high impedance in a low reception frequency band. Therefore, the reception signal of the high reception frequency band excited by the antenna conductor 1 is sent to the receiver via the capacitor 7. Capacitor 7
The capacitance value is usually about 1 to 1000 pF. For example, when the low reception frequency band is the AM broadcast band and the high reception frequency band is the FM broadcast band, the capacitance value of the capacitor 7 is preferably in the range of 5.0 to 33 pF.

The damping resistors 21 and 22 are provided as necessary. The quality factor (Q) of the first resonance or the second resonance is appropriate, and the resistance 2
It is unnecessary if the flatness of the receiving sensitivity can be ensured without providing the first and second elements. A damping resistor may be provided in addition to the resistors 21 and 22.

The capacitor 71 is for blocking a DC voltage.
Provided as needed.

[0056]

【Example】

"Example 1 (Example), Example 2 (Comparative Example), and Example 3 (Comparative Example)" As Example 1, a glass antenna device as shown in FIG. 1 was manufactured on the assumption that AM broadcast and FM broadcast were received. The low reception frequency band is the AM broadcast frequency band, and the high reception frequency band is the FM broadcast frequency band.

The size of the side window glass plate 11 is 400 mm in the upper horizontal direction, 500 mm in the lower horizontal direction, and 3 mm in the vertical direction.
It was 50 mm. The length L ₁ of the antenna conductor 1 is 630 m
m, the substantially horizontal length L ₂ of the ground conductor 13 is 560 m
m, the line width of the antenna conductor 1 is 0.7 mm, the length (width) of the ground conductor 13 in the substantially vertical direction is 0.7 mm, the distance d ₁ between the antenna conductor 1 and the ground conductor 13 is 10 mm, The shortest distance d ₂ from the vehicle body opening 4 is 35 mm, the size of the feeding point 1a is 18 mm × 18 mm, and the ground point 13a
Is 18mm × 18mm, feed point 1a and ground point 1
The shortest distance from 3a was 5 mm.

The resonance circuit shown in FIG. 4 was employed. In the resonance circuit of FIG.
High frequency coil 62, resistors 21, 22 and capacitor 71
Was provided, and the third high-frequency coil 63 was not provided. First
The coil 3 is of a chip type and has a relatively wide band.

The value of each circuit element includes the first coil 3 in the AM broadcast frequency band (500-1500 kHz).
μH and the second coil 8 was 470 μH. Also, FM
High frequency coil 6 in broadcast frequency band (88-108 MHz)
Reference numerals 1 and 62 denote 1.0 μH, AM broadcast frequency band and FM broadcast frequency band, the resistance 21 is 270Ω, the resistance 22 is 12 kΩ,
The capacitor 7 is 18 pF and the capacitor 71 is 2700
It was set to pF.

The effective capacitance C _L0 of the antenna conductor 1 is approximately 10 pF, and the stray capacitance C _L1 of the antenna conductor 1 is approximately 40 pF.
pF, stray capacitance C _H1 of cable (not shown) is approximately 120
pF.

As Example 2, a conventionally used glass antenna having a shape as shown in FIG. 5 was manufactured. In Example 2, the dimensions of the side window glass plate 1 were the same as those in Example 1, and the total length (total conductor length) of the antenna conductor 92 excluding the feeding point 92a was 1
000 mm.

Example 3 is a case where the reception signal of the antenna conductor 1 is directly sent to the receiver side without providing the resonance circuit of FIG. 4 in Example 1.

FIG. 6 is a frequency characteristic diagram of the receiving sensitivity of Example 1 and Example 2 in the FM broadcast frequency band. In Example 1, the reception sensitivity was improved over the entire FM broadcast frequency band as compared with Example 2. In Example 3, the reception sensitivity in the FM broadcast frequency band was the same as in Example 1.

FIG. 8 shows an example 1 in the AM broadcast frequency band.
FIG. 9 is a frequency characteristic diagram of the receiving sensitivity in Examples 2 and 3. In Example 1, the receiving sensitivity was improved over the entire AM broadcast frequency band as compared with Example 2. In Example 1, the resonance frequency of the first resonance is approximately 700
kHz, the resonance frequency of the second resonance is approximately 1200 kHz.
z, the first incident resonance frequency of the second resonance is approximately 550 k
Hz, the second incident resonance frequency of the second resonance is approximately 135
It was 0 kHz.

Example 4 (Example) Side window glass plate 11
The dimensions and the resonance circuit were the same as those in Example 1. Also,
The length L ₁ of the antenna conductor 1 is 650 mm, the ground conductor 1
Substantially horizontal length L ₂ of the 3 and 540 mm, for the specifications of the other conductor patterns were similar to those of Example 1.

FIG. 7 is a frequency characteristic diagram of the receiving sensitivity of Example 2 and Example 4 in the FM broadcast frequency band. In Example 4, the reception sensitivity was improved over the entire FM broadcast frequency band as compared with Example 2.

[0067]

According to the present invention, since the antenna conductor and the ground conductor are under a predetermined condition, the antenna conductor and the ground conductor are required to have a 10M band such as an FM broadcast band.
The reception sensitivity in the high frequency band of Hz or higher is high, and it is not necessary to provide a preamplifier for amplifying the reception signal between the feeding point and the receiver, and the productivity is high.

Further, since the glass antenna device for a vehicle according to the present invention is composed of a simple conductor pattern, it does not take a long time to adjust the conductor pattern to obtain the required receiving sensitivity, and the productivity is improved. The space occupied by the antenna conductor is small even if the area where the antenna conductor can be provided is narrow.

Also, the inductance of the first coil,
The first resonance is caused mainly by the stray capacitance of the antenna conductor for the low band, and the resonance frequency is lower than the high reception frequency band, thereby improving the reception sensitivity in the desired low reception frequency band. it can.

Further, according to the present invention, by causing the second resonance using the second coil 8, the reception sensitivity in a desired low reception frequency band can be improved, and the reception can be performed with excellent flatness. it can.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a typical example of a glass antenna device for a vehicle according to the present invention.

FIG. 2 is an equivalent circuit diagram of FIG.

FIG. 3 is a plan view of a typical example of a pattern of an antenna conductor 1 according to the present invention.

FIG. 4 is a circuit diagram of an application example of a resonance circuit according to the present invention.

FIG. 5 is a configuration diagram of a conventional example of a glass antenna device for a vehicle.

FIG. 6 is a diagram showing frequency characteristics of reception sensitivity in Examples 1 and 2 in an FM broadcast frequency band.

FIG. 7 is a frequency characteristic diagram of reception sensitivity in Example 4 and Example 2 in an FM broadcast frequency band.

FIG. 8 is a frequency characteristic diagram of reception sensitivity in Examples 1 to 3 in an AM broadcast frequency band.

[Explanation of symbols]

11: Rear side window glass plate 1: Antenna conductor 3: First coil 7: Bypass capacitor 8: Second coil 13: Ground conductor 1a: Feeding point 13a: Ground point 18: Third coil 21, 22: Damping resistor 61: first high-frequency coil 62: second high-frequency coil 63: third high-frequency coil 71: capacitor E _L : voltage power supply of antenna conductor 1 C _L0 : effective capacity of antenna conductor 1 C _L1 : antenna Stray capacitance of conductor 1 C _H1 : Stray capacitance of cable

Claims (3)

[Claims] 1. An antenna conductor provided on a window glass plate of a vehicle, a ground conductor, a feeding point provided on the antenna conductor, and a ground point provided on a ground conductor, and the antenna conductor and the ground conductor are substantially parallel to each other. The antenna conductor enables reception in both the low reception frequency band and the high reception frequency band, and a first coil and a capacitor are electrically connected in parallel between the antenna conductor and the receiver. Connect things electrically,
The inductance value of the first coil is set to have a low impedance at least in a low reception frequency band, and the capacitor has a capacitance value having a low impedance in a high reception frequency band and a high impedance in a low reception frequency band. The first resonance is caused by the inductance of the coil and the capacitance including the stray capacitance of the cable, so that the resonance frequency of the first resonance exists at a frequency lower than the high reception frequency band, and is opposite to the antenna conductor side. A glass antenna device for a vehicle, wherein an end of a condenser on the side and a receiver side are electrically connected by a cable. 2. The glass antenna device for a vehicle according to claim 1, wherein the width of the ground conductor is in the range of 0.2 to 10 mm. 3. The distance between the antenna conductor and the ground conductor is 1 to 3.
The glass antenna device for a vehicle according to claim 1 or 2, which is in a range of 100 mm.