JPH02311002A - Glass antenna system for automobile - Google Patents

Abstract

PURPOSE:To attain high gain and low noise without a preamplifier by providing a reactance circuit between a defogger and a DC power supply and between an antenna conductor and ground respectively and providing a matching circuit between the antenna conductor and a receiver. CONSTITUTION:A reactance circuit 8 is inserted between lead wires 22a, 22b of a defogger provided to a glass plate 1 and a DC power supply 10. Moreover, a reactance circuit 26 is inserted between a feeding point 4 of an antenna conductor 6 and a car body earth. High frequency current shield effect of the circuit 8 is regulated by varying a resistor 28 of the circuit 26. In order to make the resonance characteristic of the Q relating to the anti-resonance flat, the relation of Q<=1.2 with respect to an AM broadcast frequency band and the relation of Q<=2.4 with respect to an FM broadcast frequency band are selected. Moreover, a matching circuit 7 is provided between the feeding point 4 and a receiver 20. Then the resonance characteristic of the circuit 7 is selected so that the similar condition is satisfied for the Q with respect to the AM and FM broadcast frequency bands.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a high gain, low noise, omnidirectional glass antenna device for automobiles.

[Prior Art] As an antenna for a car radio, as an alternative to a rod antenna or a lid antenna, an antenna for AM, for FM, or for both AM and FM is installed on the surface or inside of a glass plate for the rear window of a car. Glass antennas provided with conductors are widely used. Unlike rod or lid antennas, this glass antenna does not protrude to the outside, so it is less likely to cause harm, will not break, and will not cause any damage, so there will be little change in performance ( It also has the advantage of improving the exterior design of the vehicle.

The antenna gain of this glass antenna can be increased by designing the pattern of the antenna conductor provided on the glass plate so that the desired performance can be obtained, but in the case of a glass antenna for automobiles, Because the area of the glass plate is not wide enough, the distance between the antenna conductor and the car body is forced to be narrow, which tends to increase leakage current from the antenna conductor and result in insufficient antenna gain. be.

In addition, in the case of a glass antenna for the rear window of a car, an electrically heated defogger for defogging is usually installed on the window glass plate together with a predetermined pattern of antenna conductors, so the heating wire and antenna conductor are particularly close to each other. If you are
It leaks to the car body through the power supply part of this electrically heated defogger for defogging, resulting in gain loss. Therefore, in order to prevent gain loss, a choke coil is sometimes attached to a suitable part of the feed point of an energized defogger for weighing and removal, but an automotive glass antenna using such a choke coil In this case, the choke coil does not have sufficient high frequency current blocking function, so
There is a tendency for antenna gain to be low.

In conventional glass antennas, in order to compensate for the antenna gain loss described above, a preamplifier is inserted at a suitable location in the feed line between the feed terminal of the antenna conductor and the receiver. was. However, due to the insertion of a preamplifier, there were problems such as cross-modulation or thick distortion in strong electric fields.Also, in the case of this method, there was a problem that the radio receiver was The problem is that it is quite expensive as it is necessary to install a preamplifier, and installing a preamplifier near the glass antenna is a constraint in the design of the car due to the need to secure space for the preamplifier. Therefore, it has been desired to develop a glass antenna for automobiles that does not require such a preamplifier, has high gain, low noise, and is omnidirectional.

[Problems to be Solved by the Invention] An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to provide a high-gain, low-noise, omnidirectional device that does not require an expensive preamplifier. The purpose of this invention is to provide a new glass antenna device for automobiles.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and includes a heater wire and a power supply to the heater wire attached to a glass plate of a rear window that is fitted into an opening of the rear window of an automobile. In a glass antenna device for an automobile, which is provided with an electrically heated defogger having a bus bar and an antenna conductor having a predetermined pattern, the defogger and the antenna conductor are partially connected to each other so that a direct current is not passed between them. The antennas are capacitively coupled in close proximity at a predetermined interval so that transmission and reception of high-frequency current is possible but not transmission and reception. The impedance seen from the lead wire connection part of the bus bar, which mainly consists of capacitance formed by the conductor, defogger, and vehicle body, the impedance of the reactance circuit 8 inserted between the bus bar and the DC power supply for the defogger, and the antenna. Anti-resonance is caused by the impedance of the reactance circuit 26 inserted between the feed point of the conductor and the vehicle body ground, and furthermore, for the AM broadcast frequency band, the Q resonance characteristic related to the anti-resonance is relatively flat. Q≦1.2. Set Q≦2.4 for the FM broadcast frequency band, and insert it between the feeding point of the antenna conductor and the receiver in one band other than the one band in each of the FM and AM broadcast frequency bands. The impedance of the matching circuit, the input impedance of the radio, and the impedance seen from the matching circuit to the antenna conductor side are used to cause resonance, and the resonance characteristic of Q related to the resonance is relatively flat.
For M broadcast frequency band, Q≦1.2. The present invention provides a glass antenna device for automobiles having a characteristic that Q≦2.4 for the FM broadcast frequency band.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a schematic diagram illustrating the entire glass antenna device for an automobile according to the present invention. In Figure 1, 1 is the glass plate of the rear window of the car, 2 is the heater wire, 2a is the upper part of the heater wire, 3 is the defogger, 3a is the branch line of the defogger, 4 is the feeding point of the antenna conductor, 5a, 5b , 5c is a bus bar, 6 is an antenna conductor, θa is a portion of antenna conductor 6 adjacent to defogger 3, 7 is a matching circuit, 8 is a reactance circuit, 9 is a heater transformer, IO is a DC power supply, 11 is a capacitor, and 12a.

12b is a high frequency coil, 13, 14, 17.27 are coils, 15.28 is a resistor, 16 is a capacitor, 18 is F
M band high frequency coil, 19 is a capacitor, 20 is a receiver, 21 is a ground lead wire, 22a, 22b is a lead wire, 23 is a lead wire, 24 is a rear window opening, 24a,
24b.

24c is a vehicle body ground, 25 is a cable, and 26 is an actance circuit.

The glass plate 1 of the rear window is usually made of tempered glass or laminated glass with a thickness of about 3 to 5 mm.

The heating area on the inner surface of the glass plate 1 of this rear window is an electrical heating type having a large number of heater wires 2 and opposing bus bars 5a, 5b, 5c connected to both ends of the group of heater wires 2. A defogger 3 is provided, and buspers 5a and 5b of the defogger 3 are provided with a defogger 3.
Lead wire 22a.

22b is connected. Defogger shown in Figure 1
3 divides one of the bus bars on both sides of the defogger 3, for example one bus bar, into two parts from the desired position, vertically.
A lower bus spar 5a and an upper bus spar 5b are provided, a lead wire 22a on the power supply side is connected to the lower bus spar 5a, and a lead wire 22a on the vehicle body side is connected to the upper bus spar 5b to supply power. FIG. 1 shows an example in which current flows from the lower busbar 5a through the busbar 50 to the upper busbar portion 5b in a U-shape. The example of the defogger shown in Fig. 1 consists of a number of thin electrically heated heater wires with a line width of 0.5 to 2 mm in the horizontal direction of the glass plate, which are arranged approximately parallel to each other at intervals of 2 to 4 cm. This is an electrically heated defogger that is formed by printing a paste containing a conductive metal such as paste on the inside surface of a glass plate and baking it.

6 is the defogger of the glass plate 1 for a rear window of an automobile.
This is the antenna conductor provided on the top of 3. The antenna conductor 68 and the branch line 3a of the defogger, which are the adjacent parts of the antenna conductor 6 and the defogger 3, are capacitively coupled, and no direct current is transmitted or received between them. They are placed close to each other at a predetermined interval so that high frequency current can be transmitted and received. The adjacent portion 6a and the branch line 38 portion of the defogger are spaced apart from each other by, for example, about 1 mm to 10+ nm. The antenna conductor 6 apparently functions as a part of the defogger due to capacitive coupling with the defogger 3. Especially radio broadcast A.
For the M broadcasting frequency band, the defogger 3 also functions as a part of the AM antenna, and the effective length of the AM antenna becomes longer, receiving more radio waves and increasing sensitivity.

Further, in the FM broadcast frequency band, the aperture 24 and the defogger 3 serve as a projector or a reflector for the antenna conductor 6, and the pattern of the antenna conductor 6 may be determined so as to be non-directional. On the other hand, since leakage power is induced by induction from the antenna conductor 6 to the opening 24 and the defogger 3, the loss from the defogger 3 is blocked by the coils 12a and 12b, thereby increasing the sensitivity.

In the defogger 3 shown in FIG. 1, a branch line 38 is provided at the highest heater wire 2a of the defogger 3. As shown in FIG. 1, the branch line 3a of this defogger 3 extends vertically from near the center of the upper part 2a of the highest heater wire, and branches horizontally near the adjacent portion 6a of the antenna conductor 6. It is T-shaped.

Since no current flows through the branch line 3a, there is little noise, and the capacitive coupling between the antenna conductor 6 and the defogger 3 increases the sensitivity. However, the branch line 3a of the defogger may have any shape as long as it has the above function (and is not limited to the shape shown in FIG.
It may also be shaped to extend toward the opposite side in the direction of a small flat near the area. Also, a part of the heater wire 2 can be used instead of the branch line 3a of the defogger, and the branch line 3a may be omitted, but in view of the above-mentioned noise, it is preferable to provide the branch line 3a.

Incidentally, FIGS. 6 and 7 are schematic diagrams of a defogger pattern having a different shape from that shown in FIG. 1.

As mentioned above, the defogger 3 and the antenna conductor 6 are
In order to capacitively couple a portion thereof, it is best to form the defogger 3 and the antenna conductor 6 on the same surface as the glass plate for the rear window, usually on the side of the room. The pattern of the antenna conductor 6 may be an antenna for AM band radio broadcasting, FM band radio broadcasting, both AM band and FM band radio broadcasting, or television or other broadcasting, etc., depending on the shape of the car, the shape, dimensions, and configuration of the glass plate. A pattern that provides optimal performance is appropriately selected and designed.

The example shown in FIG. 1 shows an example in which the antenna conductor 6 is provided at the top of the defogger 3 of the rear window glass plate l of an automobile, but the antenna conductor 6 is not limited to this and may be provided at the bottom of the defogger 3. Alternatively, they may be provided at the top and bottom of the defogger, respectively, or may be provided at other blank areas.

In addition, the connection terminal for connecting the antenna conductor and antenna cable by means such as soldering is made by applying a conductive metal-containing paste such as conductive silver paste to the glass plate surface, similar to the heater wire 2 of the defogger 3 described above. The most common type of antenna conductor is a linear print type that is printed and baked in a predetermined pattern, but is not limited to this, and may be an antenna conductor made of a transparent conductive film or an ultrafine conductive wire in a predetermined pattern.

In the present invention, the defogger is connected between the lead wires 22a and 22b of the defogger 3 from the DC power source 1o.
A reactance circuit is inserted so as to allow a current to flow to 3, but to cut off current in a high frequency band such as a radio broadcasting frequency band. Furthermore, a reactance circuit 26 is inserted between the power feeding point 4 and the vehicle body ground. The reactance circuit 8 includes a coil 9.
The reactance circuit 26 is composed of coils 12a, 12b and a capacitor 11, and the reactance circuit 26 is composed of coils 27. It is composed of a resistor 28. This reactance circuit 8 connects the heater wire 2 of the defogger 3 and the buspars 5a, 5b,
5c can be floated at a high frequency, and current caused by radio waves in a high frequency band such as a radio broadcasting frequency band induced in the heater cotton 2 and buspers 5a, 5b, and 5c can be prevented from flowing to the ground, and the induced current can be prevented from flowing to the ground. can be sent to the receiver without omission. Furthermore, the reactance circuit 26 can be made variable by making the resistor 28 variable.
It is possible to adjust the above effects of. The high frequency choke coil of the heater transformer 9 in the reactance circuit 8 has high impedance in a high frequency band such as a radio broadcasting frequency band, and has characteristics that prevent magnetic residual.
For example, a high-frequency choke coil in which a toroidal magnetic core (Mn-Zn phalarite, etc.) is wound with a pie filer, or a high-frequency choke coil wound in a direction that mutually cancels out the magnetic flux of the coil generated by the current from a closed magnetic circuit, or, High-frequency choke coils and the like that use cores with high magnetic saturation are used. In such high-frequency choke coils, in order to obtain the required inductance, self-resonance frequency, and Q value, the core is divided into two parts, and the core is divided into two parts. Adjustments are made by adjusting the spacing or changing the coil pitch.

Furthermore, minute adjustments can be made by varying the resistance 28 of the actance circuit 26. In other words, by finely adjusting the total inductance of the coil 27, the coil 9, and the coil 12 by varying the resistor 28, the current flowing through the coil 27 is varied, and the apparent inductance of the coil 27 is varied.

A capacitor 11 in the reactance circuit 8 is used to electrically short-circuit a noisy current with a high frequency component (for example, one that enters through a lead wire) in a high frequency band such as a radio broadcasting frequency band.

The high-frequency coils 12a and 12b in the reactance circuit 8 have high impedance in the FM broadcasting frequency band, and are usually solenoids that do not use magnetic cores, spiral coils, or lead wires of appropriate length, and are used as heaters. The high frequency choke coil of the transformer 9 has a low self-resonance frequency in the FM broadcast frequency band (and loses inductance, so the high frequency choke coil 12a
, 12b performs this on your behalf.

The coil 27 in the reactance circuit 26 may be a small coil for small current, and the resistor 28 may be of a variable type or a fixed type.

Furthermore, in the present invention, a matching circuit 7 is inserted at a desired position on the path between the feeding point 4 of the antenna conductor 6 and the receiving l'120 of a radio, etc., and the high frequency current induced in the antenna conductor 6 is The signal is caused to resonate by the impedance of the matching circuit 7, the impedance of the receiver 20, and the impedance seen from the matching circuit toward the antenna conductor side, and is sent to the receiver 20. The matching circuit 7 is composed of elements such as coils 13, 14, 17, 18, a capacitor 16, and a resistor 15. In the FM broadcasting frequency band, the self-resonance frequency of the coil 13, 14, 17 is low, so it is considered a capacitive reactance. Therefore, as a method that takes into account the frequency characteristics, it is possible to use a Ni-Zn ferrite core, a solenoid, or a spiral coil. Characteristics can be determined by each coil 18.

Further, as described above, the antenna conductor 6 and the defogger
3 is usually formed by printing conductive silver paste on the surface of a glass plate and baking it. In this case, between the adjacent antenna conductor part a and the defogger part 3a, There is a risk that the silver that has been removed will migrate, leading to a short circuit between the two. In this case, a large current will flow through the receiver 20, so
In order to prevent this, a DC blocking capacitor 19 may be inserted between the feeding point 4 of the antenna conductor 6 and the matching circuit 7.

In addition to what has been stated above, the adjustment of the matching circuit will be described. The present invention provides an antenna conductor 6 in a band on one side of the center frequency of each of the FM and AM broadcasting frequency bands.
The defogger 3 and the impedance seen from the lead wire connection of the bus bar, which is mainly composed of capacitance formed between each of the vehicle bodies, and the reactance circuit inserted between the bus bar and the DC power supply 10 for the defogger 3. 8 and the impedance of the reactance circuit 26, and Q≦ for the AM broadcasting frequency band so that the resonance characteristic of Q related to the antiresonance is relatively flat.
1.2. For the FM broadcast frequency band, set Q≦2.4, and for each of the FM and AM broadcast frequency bands,
In one band other than the one band, the impedance of the matching circuit 7 inserted between the feeding point of the antenna conductor 6 and the receiver 20, the input impedance of the receiver 20, and the matching circuit 7, the antenna conductor 6 Resonance is caused by the impedance viewed from the side, and Q≦1.2 for the AM broadcasting frequency band, and Q≦1.2 for the FM broadcasting frequency band so that the resonance characteristic of the Q related to the above resonance is relatively flat. It is necessary to set it so that ≦2.4.

In addition, the above anti-resonance and resonance frequency settings are 550 to 640 KHz and 1050 to 13 KHz in the AM broadcasting frequency band.
The desirable range is within the range of 20 KHz, and 580 to 6
10 KHz, 1170-1230 KHz are particularly desirable ranges, and 77.5-80 KHz in the FM broadcast frequency band.
．． 5MHz, 84-88MHz is a desirable range,
Particularly desirable ranges are 78.5-79.5 MHz and 85-87 MHz.

In order to satisfy the above conditions, since the patterns of the antenna conductor 6 and the like are fixed, the circuit constants of the matching circuit 7 and the reactance circuits 8 and 26 are usually changed and adjusted.

Note that the reactance circuit 8 is difficult to manufacture with a high self-resonance frequency in order to pass a large current. It is preferable to cause the resonance to occur in a lower frequency range than the frequency, and to cause the resonance to occur in a higher frequency range.

In the matching circuit according to the present invention, in the AM broadcast frequency band, the capacitor 19 is 560 pF to 1 μF, the coil 13 is 82 to 560 μH, and the capacitor 16 is 5 to 2 μF.
209F, coils 14 and 17 are preferably set to 82 to 700μH, resistor 15 is set to 200Ω to 3Ω, and coil 18 is preferably set to 1 to 10μH in the FM broadcast frequency band, while a heater transformer to which three defoggers are connected 9
The high frequency choke coil is 0.1 in the AM broadcast frequency band.
~3mH.

The FM broadcast frequency band is 1 to 5μ for coils 12a and 12b.
It is preferable to set the coil 27 in the reactance circuit 26 to 300 to 700μH1.
The resistor 28 is preferably 100 to 1000Ω, and the capacitive coupling portion between the antenna conductor 6a and the branch line 3a is FM,
It is preferable to set the value to 50 to 10.0 OOpF in both AM and AM broadcasting frequency bands, and the cable portion 25 between the feeding point 4 of the antenna conductor 6, the matching circuit 7, and the input end of the receiver 20 is such that the high frequency current is effective. It is preferable to use a method such as a coaxial cable, a feeder line, etc. for example.

Of course, these values are given as examples of typical values, and can be changed so as to obtain the optimum performance depending on the target automotive glass antenna device. In addition, the vehicle body ground 24a, which is the negative terminal of the cable 25, and the DC power supply 1
In terms of noise, it is preferable that the vehicle body ground 24c, which is the zero negative electrode, be separated by 30 cm or more, preferably 60 cm or more.

[Function] The present invention reduces the leakage current of the defogger 3 by anti-resonance in a band on one side of the center of the desired broadcasting frequency band on a logarithmic scale, and reduces resonance by using a matching circuit in bands other than the above-mentioned one side. By causing this phenomenon to occur, sensitivity is maintained over the entire broadcast frequency band. The reason why this is done is that the reactance circuit 8, the reactance circuit 26, and the matching circuit 7 cannot cover the above range by themselves.

In addition, the reactance circuit 8, which requires a large amount of current to flow, requires advanced technology to manufacture one with a high self-resonant frequency. Matching circuit 7
In order to simplify the explanation, an example will be explained in which anti-resonance is caused in the low frequency range.

The present invention is based on the following technical ideas,
The impedance of the reactance circuit 8 and the reactance circuit 26 causes what should become an antenna to anti-resonate in the above-mentioned low range, and prevents the reception current of broadcasting induced in the deogger 3 from flowing to the vehicle body side. The idea is to use a matching circuit to create resonance at approximately the center of the high frequency range on a logarithmic scale, thereby increasing sensitivity.

If the reactance circuit 8 has a high self-resonance frequency, it is possible to cause anti-resonance in the high frequency range and resonance in the low frequency range.

The operation of the present invention will be explained in detail below.

In the automotive glass antenna device of the present invention, the three elements of the antenna conductor 6, the defogger 3, and the rear window opening each take advantage of the impedance of the actance circuit 8 and the reactance circuit 26, which mainly consist of capacitance, respectively. An anti-resonance phenomenon occurs in frequencies lower than the center on a logarithmic scale of each of the FM and AM broadcasting frequency bands.

If the center value f14 is the logarithmic scale between the lowest frequency fL and the highest frequency f8 of each of the FM and AM broadcasting frequency bands, then the center value fL and fL are the logarithmic center value fL and fL. Set so that is the anti-resonant frequency. For example, in the AM broadcasting frequency band, f L "F 500k
f between Hz and f, = 1600kHz, S 900
If the circuit constants of the reactance circuit 8 and the reactance circuit 26 are set so that the anti-resonance frequency is the center value of the low frequency f04600kHz, the impedance between the defogger 3 and the rear window opening 24 will be maximum at the frequency fLM. becomes. That is, the leakage current from the defogger 3 to the opening 24 of the rear window on the vehicle body side is minimized, and the high frequency current induced by the broadcast radio waves arriving at the defogger 3 leaks to the vehicle body side, reducing the sensitivity. It can be prevented.

Similarly, for example, in the FM broadcast frequency band, f, Saki82
MHz, f L = 76 MHz, f H = 90
A similar phenomenon occurs when the frequency is set to 79 MHz. Regarding the reactance circuit 8, in the AM broadcasting frequency band, the inductance of the coils 12a and 12b is sufficiently smaller than the inductance of the heater transformer 9, so it can be ignored. Further, in the FM broadcasting frequency band, the coil 9 has a low self-resonance frequency and thus becomes a capacitive reactance, so the coils 12a and 12b have this function.

In the above case, if Q is made as small as possible in both the FM and AM broadcasting frequency bands, the impedance will be averaged in each of the FM and AM broadcasting frequency bands, and the leakage current will be reduced on average.

Further, the defogger 3 and the antenna conductor 6 are connected to an adjacent portion 6a of the adjacent antenna conductor and a branch line 3a of the defogger.
Due to capacitive coupling between the FM and AM broadcasting frequency bands, a high frequency connection is established between the FM and AM broadcasting frequency bands.

Since it is insulated from the vehicle body ground in both AM and AM broadcasting frequency bands, the defogger 3 also functions as an antenna like the antenna conductor 6.

While satisfying the above conditions, in the AM broadcasting frequency band, the center value f on a logarithmic scale of f2 900 kHz and f = 1600 kHz. The circuit constants of the matching circuit 7 are set so that it resonates around 1200kHz, and similarly in the FM broadcast frequency band,
f M→90MHz, f HMMB26 MHz
The circuit constants of the matching circuit 7 are set so that the resonance occurs at It is better to set it close to 0. By doing this, the power efficiency from the antenna to the receiver 20 can be improved, and the induced current caused by the incoming radio waves generated in the antenna can be transmitted to the receiver 20 side without leakage. can.

Furthermore, to describe the above resonance in AM and FM in detail, between the feeding point 4 of the antenna conductor 6 and the receiver 20, there are coils 13, 14, 17, 18 as shown in FIG.
, a capacitor 16, and a resistor 15, and a matching circuit 7 having an actance component is inserted. In the case of the AM broadcast band, the impedance of this matching circuit 7 is the coil 13, 14, 17, and the capacitor 1.
6, the entire antenna, and the receiver 20, the resonant frequencies are set to f, l, l, and the coils 14,
17. By setting Q to an optimum value using the resistor 15, it is possible to obtain approximately averaged sensitivity in the AM broadcasting frequency band. In addition, in the case of FM broadcast frequency band, coil 1
3, 14, 17, resistor 15, and capacitor 16 have a slight capacitive reactance due to the stray capacitance of each component, and the coil 18 resonates at the above f□ due to this, the antenna, and the input impedance of the radio. (In the matching circuit 7, only the coil 18 is effective in the FM broadcast frequency band), and the signal received by the antenna is transmitted to the radio in an optimal manner. As described above, high receiving sensitivity can be obtained in each frequency band.

The matching circuit 7 resonates with the input impedance of the entire antenna and the receiver 20 at the f It becomes possible to absorb noise such as noise, and a low-noise antenna can be obtained.

[Example] In the automotive glass antenna device of the present invention shown in FIG. 1, the values in the AM broadcasting frequency band are: capacitor 19: 0.01 μF, coil 13: 300 μH, coil 14: 150 μH, resistor 15: 680Ω, capacitor 16 is 27pF, coil 17 is 330μH, capacitive coupling between antenna conductor 68 and defogger 3a is 90pF, heater transformer 9 inductance is 400Ω.
uH, capacitor 11 is 2.2μF, coil 27 is 5
When the 60μH1 resistor 28 is 500Ω and the antenna cable portion between the feed point 4 of the antenna conductor 6 and the input end of the receiver 20 is 30pF/I11,
Figures 2 and 3 show the results of measuring the antenna gain and S/N ratio characteristics of this glass antenna device for the AM broadcasting frequency band.

Figure 2 shows the electric field strength of 130d near the glass antenna.
The antenna gain for the AM broadcasting frequency band obtained when B 1t V/m is obtained for each frequency, and is comparable to a conventional glass antenna with a preamplifier. Furthermore, FIG. 3 shows the S/N ratio characteristics obtained for each electric field strength when the carrier frequency is 400 Hz and when there is no modulation and when there is modulation. Note that when no modulation is performed, the modulation degree is 0, and when modulated, the modulation degree is 30%. In strong electric fields, the S/N ratio is the same as that of conventional glass antennas with amplifiers, but in weak electric fields, the glass antenna of the present invention achieves good results.

As described above, the glass antenna of the present invention can obtain a high gain equivalent to that of a conventional glass antenna with an amplifier, which uses an amplifier to increase the gain in the AM broadcasting frequency band, and in a normal weak electric field. Low noise can be obtained.

Furthermore, each component that is effective in the FM radio broadcasting frequency band is
Capacitor 19 is O, 01uF, coil 18 is 2μH
, the coils 12a and 12b are each 2BH, and the antenna cable portion between the feeding point 4 of the antenna conductor 6 and the input end of the receiver 2o is 30 pF/m, respectively. The antenna gain and directivity characteristics for frequency bands are shown in Figures 4 and 5.
As shown in the figure, we obtained a high-gain, non-directional FM glass antenna device that can also be used.

Incidentally, the bus par 5a in the above automobile antenna device,
The Q obtained by combining the impedance and actance circuit when looking at the heater wire 2 from 5b is 0.1 in AM. 0 for FM
．． It was 5. Also, when looking at the antenna conductor from the input end of the receiver, the total impedance Q of the antenna conductor and the functional part as an antenna is 0.2 in AM. For FM, it was 0.4.

[Effects of the Invention] According to the present invention, it is possible to provide a glass antenna for an automobile with high gain, low noise, and high omnidirectional reception performance without a preamplifier. In particular, according to the invention, AM
It is useful because it can receive radio broadcasts with high gain and low noise, and it is useful because it can receive FM radio broadcasts with high gain and omnidirectional. Similarly, it can be applied to other broadcast waves as well.

Therefore, the preamplifier can be eliminated and costs can be reduced.In addition, in the past, the preamplifier had to be installed near the glass antenna. Although there were constraints, according to the present invention, it is only necessary to install a simple matching circuit, so the above constraints can be resolved.

[Brief explanation of drawings]

FIG. 1: A schematic diagram illustrating the entire automotive glass antenna device of the present invention. FIG. 2: Frequency characteristic diagram of the AM broadcasting frequency band of the glass antenna of Example 1. FIG. 3: Characteristic diagram of the S/N ratio in the AM broadcasting frequency band of the glass antenna of Example 1. FIG. 4: Frequency characteristic diagram of the FM broadcasting frequency band of the glass antenna of Example 1. FIG. 5: Characteristic diagram of the designability of the FM broadcasting frequency band of the glass antenna of Example 1. FIGS. 6 and 7 are schematic diagrams of a defogger with a pattern different from that shown in FIG. 1 according to the present invention. 1 Glass plate 2: Heater wire 3: Defogger 4: Receiver 7: Matching circuit 8: Reactance circuit 26: Reactance circuit Figure 500 1 (XX) (dB/'T7/Canada) Fig. 4 Anti-L Kamoya (d8avλ solid concentration number CMHK) Multi 6 5 sides

Claims (4)

[Claims] (1) A vehicle in which an electrically heated defogger having a heater wire and a bus bar that feeds power to the heater wire and an antenna conductor in a predetermined pattern are provided on a rear window glass plate that is fitted into the rear window opening of the vehicle. In a glass antenna device for use in a glass antenna device, the defogger and the antenna conductor are capacitively coupled at a predetermined interval so that DC current is not transmitted and received between them, but high frequency current is transmitted and received between them. FM, A
The impedance seen from the bus bar lead wire connection, which is mainly composed of capacitance formed by the antenna conductor, defogger, and vehicle body, in a band on one side of the center frequency on a logarithmic scale of each broadcast frequency band. Anti-resonance is caused by the impedance of the reactance circuit 8 inserted between the bus bar and the defogger DC power supply and the impedance of the reactance circuit 26 inserted between the feeding point of the antenna conductor and the vehicle body ground, and furthermore, the Q related to the anti-resonance is A so that the resonance characteristics of
Set Q≦1.2 for the M broadcasting frequency band and Q≦2.4 for the FM broadcasting frequency band, and
The impedance of the matching circuit inserted between the feeding point of the antenna conductor and the receiver, the input impedance of the receiver, and the antenna conductor side from the matching circuit in one band other than the one band in each of the M broadcasting frequency bands. Furthermore, in order to make the resonance characteristic of Q related to the resonance relatively flat, Q≦1.2 for the AM broadcast frequency band and Q≦ for the FM broadcast frequency band. A glass antenna device for an automobile, characterized in that it has an antenna of 2.4. (2) A vehicle in which an electrically heated defogger having a heater wire and a bus bar that feeds power to the heater wire and an antenna conductor in a predetermined pattern are provided on a rear window glass plate that is fitted into the rear window opening of the vehicle. In a glass antenna device for use in a glass antenna device, the defogger and the antenna conductor are capacitively coupled at a predetermined interval so that DC current is not transmitted and received between them, but high frequency current is transmitted and received between them. FM, A
The impedance seen from the lead wire connection of the bus bar, which is mainly composed of capacitance formed by the antenna conductor, defogger, and vehicle body, and the bus bar at a frequency lower than the center frequency on a logarithmic scale of each broadcast frequency band. Anti-resonance is caused by the impedance of the reactance circuit 8 inserted between the DC power supply for the defogger and the impedance of the reactance circuit 26 inserted between the feeding point of the antenna conductor and the vehicle body ground, and furthermore, the Q resonance related to the above-mentioned anti-resonance is caused. In order to make the characteristics relatively flat, set Q≦1.2 for the AM broadcast frequency band and Q≦2.4 for the FM broadcast frequency band, and set the Q≦2.4 for the FM and AM broadcast frequency bands. Resonance is caused by the impedance of the matching circuit inserted between the feeding point of the antenna conductor and the receiver, the input impedance of the receiver, and the impedance seen from the matching circuit toward the antenna conductor at frequencies higher than the center frequency on a logarithmic scale. Furthermore, in order to make the resonance characteristic of Q related to the resonance relatively flat, Q≦1.2 for the AM broadcasting frequency band and Q≦2.4 for the FM broadcasting frequency band. An automotive glass antenna device characterized by: (3) As a reactance circuit connected to the defogger, a heater transformer with a core made of a toroidal magnetic material with sufficient magnetic permeability in the AM broadcasting frequency band is connected to two poles of the defogger bus bar, and a DC power source is connected to the other end. Furthermore, between the DC power supply and the heater transformer, insert a high frequency coil that can be used up to the FM broadcasting frequency band where residual magnetism does not occur, and connect the negative pole of the DC power supply to the vehicle body at least 30 cm away from the negative pole of the cable. The glass antenna device for an automobile according to claim 1 or 2, characterized in that the antenna device is connected at a position. (4) The reactance circuit 26 inserted between the feeding point of the antenna conductor and the vehicle body ground consists of a two-terminal network circuit in which a resistor and a coil are connected in series, and the anti-resonance frequency can be varied by varying the resistor. The glass antenna device for an automobile according to claim (1), claim (2), or claim (3), characterized in that the antenna device is configured to be able to