JPH098527A - Glass antenna system for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reception sensitivity at a low reception frequency band by resonating the antenna system with a stray capacitance of a low reception frequency band antenna conductor, a stray capacitance of a high reception frequency band antenna conductor and a circuit component including an inductive component and a capacitive component so as to bring a resonance point in existence at a lower frequency than the high reception frequency band. SOLUTION: A stray capacitance of an antenna conductor 1 is made up of an effective capacitance of the antenna conductor 1 and an ineffective capacitance of the antenna conductor 1. A stray capacitance of an antenna conductor 2 is made up of an effective capacitance of the antenna conductor 2 and an ineffective capacitance of the antenna conductor 2. In order to improve the reception sensitivity, the antenna system is resonated by using the stray capacitance of the antenna conductor 1, the stray capacitance of the antenna conductor 2, a stray capacitance of an RF choke coil 3, a high frequency RF choke coil 01, and an RF choke coil 301 and a dumping resistor 5 (circuit component including inductive and capacitive component) so as to set a resonance frequency to be in existence at a lower frequency band than an FM band, that is, a high reception frequency band.

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 a receiving device for a vehicle and is used for receiving radio, television, telephone and satellite communications.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, an electrically heated defogger 33 having a heater wire 32 and a bus bar for supplying power to the heater wire 32 is provided on a glass plate 31 of a rear window of an automobile.
And a defogger 33, a direct current is not transmitted and received, but a high frequency current is transmitted and received. A glass antenna device in which a choke coil 39 is inserted and connected between the DC power supplies 10 for the defogger 33 is known.

In this prior art, a choke coil 39 is inserted between a bus bar and a DC power supply 10 for the defogger 33, and the impedance of the choke coil 39 is increased in a high frequency band such as a broadcast frequency band. To the defogger 33, but cut off the current in the broadcast frequency band.

In this way, the choke coil 39 can insulate the heater wire 32 of the defogger 33 and the bus bar from the vehicle body ground (ground) in a high frequency manner, and the high frequency band such as the broadcast frequency band induced in the heater wire 32 and the bus bar. It is possible to prevent the received current from flowing to the vehicle body ground, and to send this received current to the receiver 20 without leakage.

In the drawings other than FIG. 4, the parts having the same numbers and the same numerals as those in FIG. 4 have the same names as those in FIG.

Further, in the prior art (not shown) other than that shown in FIG. 4, an antenna for an AM broadcast frequency band (hereinafter referred to as an AM band) is provided on a glass plate of a window of an automobile in order to improve reception sensitivity. In the conventional glass antenna device in which the conductor and the antenna conductor for the FM broadcast frequency band (hereinafter referred to as the FM band) are separately provided, the antenna conductor occupies a large area, and there is a problem that the visual field is deteriorated.

[0007]

In the prior art of FIG. 4, since the glass plate 31 of the rear window is heated, a large direct current of several amperes flows through the choke coil 39 and a high frequency such as a broadcast frequency band. The current in the band is cut off to prevent the inductance from decreasing due to magnetic saturation.
Usually, it is necessary to adopt a special winding structure.

Further, the inductance of the choke coil 39 is usually as large as 0.6 to 1 mH, and the direct current resistance needs to be lowered to suppress the power loss. Therefore, the winding used for the choke coil 39 has a wire diameter of Must use thick windings.

Further, in the FM band, the antenna conductor 3
When mutual interference between 6 and the defogger 33 occurs, the reception sensitivity in the FM band decreases. The reason for this is the choke coil 3
This is because 9 becomes capacitive in the FM band and the reactive current increases in the FM band.

As described above, when the defogger 33 is used to secure good reception sensitivity, it is structurally large,
In addition, a large and heavy choke coil and a measure to reduce the reception sensitivity in the FM band are required, and the entire glass antenna device is structurally complicated, resulting in poor productivity.

Even when the AM band antenna conductor and the FM band antenna conductor are separately provided on the glass plate of the window of the automobile, the AM band antenna conductor and the AM band antenna conductor are received when the AM broadcast is received. There has been a demand for a glass antenna device capable of improving reception sensitivity and receiving efficiently by using both of the FM band antenna conductors.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a low receiving frequency band antenna conductor and a high receiving frequency band antenna conductor are provided on a glass plate of an automobile window. Providing two or more antenna conductors including
A circuit component including an inductance component and a capacitance component connects the low reception frequency band antenna conductor and the high reception frequency band antenna conductor, and the inductance component has a high impedance in a frequency band higher than the low reception frequency band, Resonance is caused by the stray capacitance of the low-reception frequency band antenna conductor, the stray capacitance of the high-reception frequency band antenna conductor, and the circuit component including the inductance component and the capacitance component. The present invention provides a glass antenna device for an automobile, characterized in that

Further, according to the present invention, two or more antenna conductors including an antenna conductor for a low reception frequency band and an antenna conductor for a high reception frequency band are provided on a glass plate of an automobile window,
A circuit component including an inductance component and a capacitance component connects the low reception frequency band antenna conductor and the high reception frequency band antenna conductor, and the inductance component has a high impedance in a frequency band higher than the low reception frequency band, The floating capacitance of the antenna conductor for the low reception frequency band is caused by the stray capacitance of the antenna conductor for the low reception frequency band, the stray capacitance of the antenna conductor for the high reception frequency band, and the circuit component including the inductance component and the capacitance component. A band elimination filter circuit having an attenuation frequency between the low reception frequency band and the high reception frequency band due to the capacitance, the stray capacitance of the antenna conductor for the high reception frequency band, and the circuit component including the inductance component and the capacitance component. And the resonance frequency exists in the lower range than the attenuation frequency. To provide a glass antenna device for an automobile, characterized in that the the like.

Further, the present invention provides the above glass antenna device for an automobile, in which an inductance component parallel to the reactive capacitance of the antenna conductor for the low reception frequency band is connected between the antenna conductor for the low reception frequency band and the ground. To do.

Further, the present invention provides the above glass antenna device for an automobile, wherein the low reception frequency band is the AM broadcast frequency band and the high reception frequency band is the FM broadcast frequency band.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 shows a basic configuration diagram of a representative example of the present invention. In FIG. 1, 1 is an antenna conductor for the AM band, 2 is an antenna conductor for the FM band, 3 is an RF choke coil that is an inductance component, 301 is an inductance component, and the inductance of the RF choke coil 3 in the high frequency band A high frequency RF choke coil for complementing the reduction, 4 a power supply terminal, 5 a damping resistor, 10 a DC power supply, 20 a receiver, 19 a coupling capacitor,
20 is a receiver, 31 is a glass plate of a rear window, and 33 is a defogger.

In the figures other than FIG. 1, the same numbers and reference numerals as in FIG. 1 are the same as those in FIG.

In FIG. 1, it is assumed that both AM and FM broadcasts are received. The AM band antenna conductor 1 corresponds to the low reception frequency band antenna conductor, and the FM band antenna conductor 2 is used. Corresponds to the antenna conductor for the high reception frequency band.

According to the present invention, in the case of AM broadcast reception, R
F choke coil 3 and high frequency RF choke coil 30
Since 1 and 1 have low impedance, the antenna conductor 1 and the antenna conductor 2 are connected. The sum of the effective lengths of both antenna conductors 1 and 2 gives A
This is to improve the reception sensitivity of M broadcasting. Therefore, the sum of the effective lengths of both the antenna conductor 1 and the antenna conductor 2 is preferably a length suitable for AM broadcast reception. The RF choke coil 3 and the RF choke coil for high frequency 301 are usually used at about 1 μH to 1 mμH.

The high frequency RF choke coil 301 is an RF
It is an inductance component for complementing the inductance component of the choke coil 3. Normally, the RF choke coil 3 has a high impedance at a frequency higher than the AM band, but does not have a high impedance at the FM band.
The high frequency RF choke coil 301 having a high impedance in the FM band makes the RF choke coil 3 and the high frequency RF choke coil 301 have a high impedance in a wide frequency band from a frequency higher than the AM band to the FM band.

If only the RF choke coil 3 can provide a high impedance in a wide frequency band from a frequency higher than the AM band to the FM band, the RF choke coil 3 for high frequency is used.
01 is unnecessary and can be omitted.

If it is an element having a function as an inductance component, another element may be used instead of the RF choke coil 3 or the high frequency RF choke coil 301. Further, as long as the component has a high impedance in a wide frequency band from a frequency higher than the AM band to the FM band, a "circuit component including an inductance component" including a capacitor and a resistance component can be used.

Further, because of the above-mentioned operation, AM
In the case of broadcast reception, the received signal of the antenna conductor 1 is RF.
Choke coil 3, high frequency RF choke coil 30
1, the power supply terminal 4, and the coupling capacitor 19 are transmitted in this order, and both reception signals of the antenna conductor 2 and the antenna conductor 1 are input to the receiver 20 via the power supply terminal 8.

It is preferable that the antenna conductors 1 and 2 and the defogger 33 are not capacitively coupled so that the received signals excited in the antenna conductors 1 and 2 do not leak to the vehicle body ground.

The coupling capacitor 19 is for cutting DC current and protecting each circuit element and the receiver 20, and is short-circuited at a reception frequency such as a broadcast frequency. Therefore, the coupling capacitor 19 can be omitted if there is no risk of failure of each circuit element or the receiver 20.

The damping resistor 5 is composed of the antenna conductors 1, 2
Has a function of reducing the Q (quality factor) when the RF choke coil 3 and the RF choke coil for high frequency 301 resonate with each other, and usually has a value of several tens Ω to several MΩ. Even if there is no damping resistor 5, if the Q due to the resonance is small, the damping resistor 5
Can be omitted.

The band elimination filter circuit for preventing interference according to the present invention is the lowest range of high reception frequency band (76 MHz in FM band) and the highest range of low reception frequency band (1600 kHz in AM band). The filter circuit has a frequency characteristic of attenuating the passage of frequencies in the frequency range sandwiched between (a) and (b).

FIG. 2 is an equivalent circuit of FIG. In FIG. 2, 3a is a stray capacitance of the RF choke coil 3, 6
Is the effective capacitance of the antenna conductor 1, 7 is the reactive capacitance of the antenna conductor 1, 8 is the reactive capacitance of the antenna conductor 2 and the stray capacitance of the cable, and 9 is the load resistance. Since the effective capacity of the antenna conductor 2 is so small that it can be ignored, it is omitted in FIG.

The effective capacitance 6 of the antenna conductor 1 and the ineffective capacitance 7 of the antenna conductor 1 constitute a stray capacitance of the antenna conductor 1, and the ineffective capacitance 8 of the antenna conductor 2 and the effective capacitance of the antenna conductor 2 constitute the antenna conductor 2. Configure stray capacitance.

The stray capacitance 3a is usually several tens of MHz and several p.
The stray capacitance of the high frequency RF choke coil 301 is about F and is usually small enough to be ignored.
Has been omitted.

In the present invention, in order to improve the receiving sensitivity, the stray capacitance of the antenna conductor 1, the stray capacitance of the antenna conductor 2, the RF choke coil 3, the RF choke coil for high frequency 301, the stray capacitance 3a and the damping resistor. 5 (a circuit component including an inductance component and a capacitance component), and the resonance frequency needs to exist in the FM band, that is, in the lower region than the high reception frequency band.

Regarding the frequency band in which the resonance frequency exists, from the viewpoint of improving the receiving sensitivity, 500 kHz (the lowest frequency f _{L in the} AM band, that is, the low receiving frequency band) and 1200
It is more desirable that the resonance frequency is present in a frequency band between the frequency (2400 kHz) that is twice the frequency (the highest frequency f _H of the low reception frequency band), and the resonance frequency is present in the AM band, that is, the low reception frequency band. Is especially desirable.

Further, by appropriately selecting the constant value of the circuit such as the RF choke coil 3, it is desirable that the receiving sensitivity is as flat as possible in the AM band, that is, the entire low receiving frequency band, and the low receiving frequency is preferable. The difference between the maximum receiving sensitivity and the minimum receiving sensitivity in the entire band is more preferably within 20 dB, particularly preferably within 10 dB.

The circuit shown in FIG. 2 is preferably operated as a band elimination filter,
Further, when operated as a band elimination filter, it is necessary to make the resonance frequency exist in a range lower than the attenuation frequency.

The attenuation value at the attenuation frequency of the band elimination filter is preferably 10 dB or more, more preferably 20 dB or more in the FM band, that is, in the high reception frequency band. Further, the resistor 5 functions as a damping resistor.

In a normal automobile, the effective capacitance 6, the ineffective capacitance 7, the ineffective capacitance of the antenna conductor 2 and the stray capacitance of the cable 8 are used.
Are tens to hundreds of pF in the AM band.

FIG. 3 shows a basic configuration diagram of an application example of the present invention which is of a type different from that of FIG. In FIG. 3, 10
Reference numeral 0 is a coil including a second inductance component that resonates in parallel with the reactive capacitance 7 of the antenna conductor 1. Such parallel resonance improves the AM band reception sensitivity. In FIG.
Although the high frequency RF choke coil 301 and the damping resistor 5 are omitted, they may be provided.

The glass plate 31 of the rear window shown in FIG. 1 is usually made of tempered glass or laminated glass of about 3 to 5 mm. An electrically heated defogger 33 having a large number of heater wires and opposing bus bars connected to both ends of the heater wire group is provided in the heated area on the inner surface of the glass plate 31 of the rear window. Lead wires are connected to the bus bar 33.

The defogger 33 shown in FIG. 1 will be described. The defogger 33 is composed of a heater wire and a bus bar. The heater wire is usually formed by forming a large number of thin heater wires for electric heating having a wire width of 0.5 to 2 mm at a distance of 2 to 4 cm substantially parallel to the lateral direction on the glass plate.

Further, bus bars for supplying a current to the heater wire are formed on both sides of the heater wire. The heater wire, the bus bar, and the antenna conductors 1 and 2 are usually manufactured by printing a conductive metal-containing paste such as a conductive silver paste on the inside surface of a glass plate and baking it.

The pattern of the antenna conductor 2 is AM
It is not limited to broadcasting and FM broadcasting, but AM broadcasting and F broadcasting are possible depending on the specifications, shape, glass plate shape, size, configuration, etc. of the automobile.
A pattern that provides optimum performance as an antenna for both M broadcast, AM broadcast and FM broadcast shared radio broadcast, or television or other broadcast is appropriately selected and designed.

As for the antenna conductor 2, in the case of FIG. 1, the antenna conductor 2 is provided in the margin above the defogger 33 of the glass plate 31 of the window. The position of the glass plate 31 of the window in which the antenna conductors 1 and 2 are provided is not limited to the position shown in FIG. 1, and may be a blank part below the defogger 33 of the glass plate 31. In addition, the defogger 33
It may be provided in each of the upper and lower portions of the above, or may be provided in the other blank portion. Further, the glass plate 31 of the window may be provided with another antenna conductor other than the antenna conductors 1 and 2.

In FIG. 1, a rear window glass plate 31 provided with a defogger is shown as an example of the window glass plate. However, the present invention is not limited to this, and the window glass plate without the defogger is provided. Can be used even as a window glass plate, front window glass plate, side window glass plate,
It can also be used as a glass plate for a roof window.

FIG. 6 shows a basic structure of a typical example of the present invention of a type different from that of FIG. In FIG. 6, reference numeral 61 is an antenna conductor for a low reception frequency band, 62 is an antenna conductor for a high reception frequency band, 63 is a dark color concealing film provided on the periphery of the glass plate of the side window, and 64 is an antenna conductor for a high reception frequency band. 62 is a power supply terminal, and 65 is a power supply terminal of the low reception frequency band antenna conductor 61. Note that, in FIG. 6, parts having the same numbers and the same reference numerals as those in the other figures have the same names. In FIG. 6, the coil 100 and the reactive capacitance of the antenna conductor 61 cause parallel resonance, and the parallel resonance improves the reception sensitivity in the AM band.

Further, in the present invention, the number of antenna conductors provided on the glass plate of the window of the automobile is not limited, and the glass antenna of the present invention and other antennas such as a pole antenna and / or other glass. Diversity reception may be performed with the antenna. That is, a plurality of antenna conductors are provided on a glass plate of a window of an automobile, and an appropriate one or a stronger one of the reception signals of the plurality of antenna conductors is selected by a selection circuit connected between each antenna and the receiver. Send to receiver.

In the present invention, the "appropriate one of the received signals of a plurality of antenna conductors" means the one with a strong received signal or the one with a good S / N ratio.

For example, a glass antenna as shown in FIG. 6 is provided on each of the glass plates of the left and right side windows, and diversity reception is performed between the glass antennas.

In the present invention, the stray capacitance of the antenna conductor for the low reception frequency band, the stray capacitance of the antenna conductor for the high reception frequency band, and the circuit component including the inductance component and the capacitance component cause resonance. Since the resonance point is present in the low frequency band higher than the high reception frequency band, the reception sensitivity in the low reception frequency band is improved.

When a plurality of antenna conductors are provided on one glass plate, crosstalk is usually caused between the antenna conductors due to stray capacitance, inductance, etc. of each antenna conductor and cable. This is called interference. This crosstalk has a specific frequency characteristic, and the reception interference of the interfered antenna becomes large in the reception frequency band where the gain of the frequency characteristic of this crosstalk becomes high.

In the present invention, a glass plate for an automobile window is provided with
Two or more antenna conductors including two antenna conductors having different reception frequency bands are provided, and the low reception frequency band antenna conductor and the high reception frequency band antenna conductor having different reception frequency bands include an inductance component and a capacitance component. Connected by a circuit component, the inductance component has a high impedance in a frequency band higher than the low reception frequency band, the floating capacitance of the antenna conductor for the low reception frequency band and the floating capacitance of the antenna conductor for the high reception frequency band. A band elimination filter circuit having an attenuation frequency between the low reception frequency band and the high reception frequency band is configured by the capacitance and the circuit component including the inductance component and the capacitance component.

As a result, the band elimination filter circuit having the frequency characteristic for eliminating the influence of the frequency characteristic of the crosstalk is provided between the two antenna conductors, and the band elimination filter circuit causes the interference. The S / N ratio is drastically improved by preventing the deterioration of the reception sensitivity and the deterioration of the S / N ratio due to crosstalk.

[0052]

【Example】

Example 1 A glass antenna device as shown in FIG. 1 was created. The RF choke coil 3 for the AM band is a chip-type coil, and a relatively wide band RF coil is used.
70 μH, 4.7 μH in FM band, and the stray capacitance of the RF choke coil 3 is 1.2 p at 10 MHz.
It was F. The RF choke coil 301 for high frequency and the damping resistor 5 were not provided.

The effective capacitance 6 was 20 pF in the AM band, the reactive capacitance 7 was 120 pF in the AM band, and the stray capacitance 8 of the reactive capacitance and the cable was 150 pF in the AM band. Further, the coupling capacitor 19 is 1000 in the AM band and the FM band.
It was pF.

The closest distance between the antenna conductor 1 and the defogger 33 was 40 mm, and the antenna conductor 1 and the defogger 33 were not capacitively coupled. The closest distance between the antenna conductor 2 and the uppermost part of the heater wire of the defogger 33 was 50 mm, and the antenna conductor 2 and the defogger 33 were not capacitively coupled.

As a comparative example, a glass antenna device as shown in FIG. 4 was prepared. The antenna conductor 2 of FIG. 1 and the antenna conductor 36 of FIG. 4 have the same size and shape. FIG.
, A choke coil 39 of 1 mH is used, and the antenna conductor 36 and the defogger 33 are 10 mm at the shortest distance.
And were capacitively coupled.

Comparing the example 1 and the comparative example for both AM broadcasting and FM broadcasting, the S / N ratio of the example 1 is AM than the comparative example.
The band was about 2 dB better, and the FM band was about 1 dB better. Further, when comparing Example 1 and Comparative Example, there was almost no difference in receiving sensitivity, and the difference was within approximately 1 dB.

In Example 1, since the large choke coil 39 is unnecessary, it is not necessary to manufacture the choke coil 39, the productivity is remarkably improved, and the glass antenna device can be miniaturized.

(Example 2) RF choke coil 3 for AM band
Is a chip type coil having a relatively narrow band, is 270 μH in the AM band, is capacitive in the FM band, and the stray capacitance of the RF choke coil 3 is 10 MH.
z is 1.2 pF, and RF choke coil for high frequency 3
01 is 3.3μH in FM band, self-resonant frequency is 83MH
A glass antenna device as shown in FIG. 1 having the same specifications as in Example 1 was prepared except that z and damping resistance 5 were 12 kΩ in the AM band and the FM band. In Example 2, F from Example 1
The result was almost the same as in Example 1 except that the receiving sensitivity in the M band was approximately 1 dB. FIG. 5 shows the reception sensitivity characteristics of the AM band to the FM band of Example 2.

Example 3 A glass antenna device for an automobile was manufactured in exactly the same manner as in Example 2 except that the coil 100 was provided as shown in FIG. The coil 100 was set to 330 μH.
The reactive capacitance 7 of the antenna conductor 1 and the coil 100 resonated in parallel, and the sensitivity in the AM band was improved by almost 2 dB as compared with Example 2.

Example 4 A glass antenna device as shown in FIG. 6 was prepared. The antenna conductor 62 for the high reception frequency band has a length such that it resonates in the US FM band (88 to 108 MHz). The RF choke coil 3 for the AM band is a chip type coil and uses a relatively wide band.
270 μH in the band, 4.7 μH in the FM band, and R
The stray capacitance of the F choke coil 3 was 1.2 pF at 10 MHz.

Further, a high frequency RF choke coil 301
Is 3.3 μH in the FM band, the self-resonant frequency is 83 MHz,
The damping resistor 5 used has a resistance of 20 kΩ in the AM band and the FM band. The coil 100 was set to 330 μH.

In Example 4, the reactive capacitance of the antenna conductor 61 and the coil 100 resonated in parallel. On the other hand, the glass antenna as shown in FIG.
The power supply terminals 64 and 65 were directly connected to a receiver (not shown) without using the circuit shown in FIG.

Comparing Example 4 with the comparative example in Example 4 for both AM broadcasting and FM broadcasting, the average receiving sensitivity is shown in Example 4.
Is approximately 5 dB better in the AM band and approximately 1 in the FM band than the comparative example.
dB was good.

[0064]

According to the present invention, the stray capacitance of the antenna conductor for the low reception frequency band, the stray capacitance of the antenna conductor for the high reception frequency band, and the circuit component including the inductance component and the capacitance component cause resonance, Since the resonance point exists in the lower frequency range than the reception frequency band, the reception sensitivity in the low reception frequency band is improved.

Further, in the present invention, the band elimination filter circuit having the frequency characteristic for eliminating the influence of the frequency characteristic of the crosstalk is provided between the two antenna conductors, and the band elimination filter circuit causes interference. The S / N ratio is drastically improved by preventing the reception sensitivity deterioration and the S / N ratio deterioration due to crosstalk.

Further, in the present invention, even when the antenna conductor is provided on the glass plate of the rear window provided with the defogger, since the defogger is not used as an antenna, a large choke coil for the defogger is not required, This can contribute to downsizing of the glass antenna device and improvement of productivity.
Further, in the FM band, mutual interference between the antenna conductor and the defogger is small, and the FM caused by the mutual interference is small.
There is little decrease in the reception sensitivity of the band.

On the glass plate of the window of the automobile, for example,
An antenna conductor for the AM band and an antenna conductor for the FM band are separately provided, and by using both the antenna conductor for the AM band and the antenna conductor for the FM band at the time of receiving the AM broadcast, the reception sensitivity of the AM broadcast is improved. It is possible to improve the reception efficiency.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a representative example of the present invention.

2 is an equivalent circuit diagram of FIG.

FIG. 3 is a basic configuration diagram of Example 2

FIG. 4 is a basic configuration diagram of a conventional example.

FIG. 5 is a characteristic diagram of the reception sensitivity in the AM band to the FM band of Example 2.

FIG. 6 is a basic configuration diagram of a typical example of the present invention different from that of FIG.

[Explanation of symbols]

 1: Antenna conductor for AM band 2: Antenna conductor for FM band 3: RF choke coil 301: RF choke coil for high frequency 4: Feeding terminal 5: Damping resistor 10: DC power supply 20: Receiver 19: Coupling capacitor 20 : Receiver 31: Rear window glass plate 33: Defogger

Claims (4)

[Claims] 1. A glass plate of an automobile window is provided with two or more antenna conductors including an antenna conductor for a low reception frequency band and an antenna conductor for a high reception frequency band, and a circuit component including an inductance component and a capacitance component. The low reception frequency band antenna conductor is connected to the high reception frequency band antenna conductor so that the inductance component has a high impedance in a frequency band higher than the low reception frequency band, and the low reception frequency band antenna conductor has Resonance is caused by the stray capacitance, the stray capacitance of the antenna conductor for the high reception frequency band, and the circuit component including the inductance component and the capacitance component, so that the resonance point exists in the low range from the high reception frequency band. A glass antenna device for automobiles. 2. A glass plate of an automobile window is provided with two or more antenna conductors including an antenna conductor for a low reception frequency band and an antenna conductor for a high reception frequency band, and a circuit component including an inductance component and a capacitance component. The low reception frequency band antenna conductor is connected to the high reception frequency band antenna conductor so that the inductance component has a high impedance in a frequency band higher than the low reception frequency band, and the low reception frequency band antenna conductor has The stray capacitance, the stray capacitance of the antenna conductor for the high reception frequency band, and the circuit component including the inductance component and the capacitance component resonate, and the stray capacitance of the antenna conductor for the low reception frequency band and the antenna for the high reception frequency band Due to the stray capacitance of the conductor and the circuit components including the inductance and capacitance components, A glass antenna device for an automobile, characterized in that a band elimination filter circuit having an attenuation frequency between several bands and a high reception frequency band is configured, and a resonance frequency exists in a region lower than the attenuation frequency. . 3. An inductance component that resonates in parallel with the reactive capacitance of the low reception frequency band antenna conductor is connected between the low reception frequency band antenna conductor and ground.
Automotive glass antenna device. 4. The glass antenna device for an automobile according to claim 1, 2 or 3, wherein the low reception frequency band is an AM broadcasting frequency band and the high reception frequency band is an FM broadcasting frequency band.