JPH08148919A - Glass antenna for automobile - Google Patents

Abstract

PURPOSE: To make an antenna compact and to raise sensitivity by connecting at least one of plural power feeding points to the other more than two power feeding points through an antenna conductor, unbalancing the balance signals of the reception signals of the respective pairs of the power feeding points for which the two feeding points selected from the plural power feeding points are set, selecting them by a selection circuit and using them. CONSTITUTION: The power feeding points 21-23 and the antenna conductors 24 and 25 are provided on the antenna plate 1 of a rear window and the power feeding point 22 is connected to the power feeding points 21 and 23 respectively through the antenna conductors 24 and 25. Then, the balance signals among the respective power feeding points 21-23 are unbalanced by a balance-unbalance transformation circuit 26 and selected by the selection circuit 27. Thus, the reception signals between the power feeding points 21 and 22 for utilizing the antenna valid length of the antenna conductor 24, the reception signals between the power feeding points 22 and 23 for utilizing the valid length of the antenna of the antenna conductor 25 and the reception signals between the power feeding points 21 and 23 for utilizing the valid length of the antenna which is the sum of the antenna conductor 24 and the antenna conductor 25 are utilized, space is saved and efficient reception is made possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile glass antenna suitable for receiving television radio waves.

[0002]

2. Description of the Related Art Conventionally, as a television antenna device for an automobile, a defogger including a heater wire 2 and the like is provided on a glass plate 1 of a rear window of an automobile as shown in FIG. 8, and antenna patterns having different antenna patterns are provided around the defogger. Four antenna conductors 81, 82, 8 for receiving television broadcasting
Glass antennas with 3, 84 are already on sale. In FIG. 8, 9 is a choke coil, 10 is a DC power source, 11 is a capacitor, and 12a and 12b are high frequency coils.

As shown in FIG. 8, the reason for providing four antenna conductors for receiving television broadcasting having different antenna patterns is that the VHF band of television broadcasting is VHF-high.
h band (170 to 220 MHz), VHF-low band (9
It is divided into 0 to 110 MHz), and VHF-high
This is because there is no television broadcast wave in the frequency band between the h band and the VHF-low band, and the divided frequency bands are adjusted to the VHF-high band and the VHF-low band, respectively. This is for preparing antenna conductors having different antenna patterns and selecting and using an appropriate antenna conductor from the plurality of antenna conductors by the selection circuit 30 to ensure a certain level or more of receiving sensitivity at both broadcast frequencies.

However, in recent years, an antenna conductor for receiving AM broadcasts, an antenna conductor for receiving FM broadcasts, an antenna conductor for a keyless system for opening and closing a door lock by using radio waves, on a glass plate of a rear window of an automobile, In many cases, a telephone antenna, a GPS antenna, etc. are provided. Therefore, as shown in FIG. 8, in the conventional configuration in which a plurality of antenna conductors that occupy a large space as an antenna for television broadcasting are provided, there is a problem that it is difficult to secure an area in which an antenna conductor other than that for television is provided, and the antenna is occupied. There has been a demand for the development of an antenna conductor for a television that has a small space.

Further, in the conventional automobile television antenna apparatus as shown in FIG. 8, it is not always possible to obtain received signals having different phases from a plurality of antenna conductors, so that it is difficult to improve directivity. .

[0006] Further, conventionally, the VHF-high band and the VHF-low band which are divided frequency bands are received,
Furthermore, when trying to receive the UHF band (470 to 770 MHz) as well, a great number of tuning steps were required to obtain good reception performance in all frequency bands, and productivity did not improve. .

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and it is compact and requires a small number of tuning steps, which contributes to the improvement of productivity. A new high-performance glass antenna for automobiles will be provided.

[0008]

The present invention has been made to solve the above-mentioned problems, and functions as a plurality of feed points for a dipole antenna and a dipole antenna connected to each of these feed points. A plurality of antenna conductors are provided on a glass plate of a window of an automobile, and a balanced-unbalanced conversion circuit for converting a balanced signal of these antenna conductors into an unbalanced signal and a selection circuit for selecting an appropriate received signal. At least one of the plurality of feeding points is connected to the other two or more feeding points via respective antenna conductors, and at least one set of two feeding points selected from the plurality of feeding points is provided. Balance the balanced signals of the received signals of each set −
Provided is a glass antenna for an automobile, wherein an appropriate received signal is selected from a received signal converted into an unbalanced signal by an unbalanced conversion circuit and used by a selection circuit.

The present invention also provides the above glass antenna for a vehicle, wherein at least one of the plurality of antenna conductors is capacitively coupled to another antenna conductor.

Further, according to the present invention, an antenna conductor connected to at least one of the plurality of feeding points is arranged so as to surround another feeding point, and the antenna conductor is further extended to further extend the other feeding point. There is provided the glass antenna for an automobile, which is connected to a power feeding point.

Further, according to the present invention, at least one of the plurality of antenna conductors is close to an electric heating type defogger having a heater wire provided on a glass plate of a rear window of an automobile and a bus bar for feeding the heater wire. The defogger is capacitively coupled so that direct current is not sent to or received from the defogger, but high-frequency current is sent or received.Between one bus bar and the battery and between the other bus bar and ground. A glass antenna for an automobile is provided, in which a choke coil is inserted and connected to the glass antenna.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration diagram showing one of typical examples of the glass antenna for an automobile of the present invention.

In FIG. 1, 1 is a glass plate of a rear window of an automobile, 2 is a heater wire, 3 is an electrically heated defogger, 5a and 5b are bus bars, 9 is a choke coil, and 10 is a choke coil.
Is a DC power supply, 11 is a capacitor, 12a and b are high frequency coils, 21, 22 and 23 are feeding points, 24 and 25 are antenna conductors, 26 is a balanced-unbalanced conversion circuit, 27 is a selection circuit, and 28 is a necessary circuit. TV amplifier, 29
Is a television receiver. In addition, in each of the drawings shown below, the parts having the same numbers as those in FIG. 1 have the same names.

In the configuration example shown in FIG. 1, three feeding points 2 are provided.
1, 22, 23 and antenna conductors 24, 25 connected to the feeding points 21, 22, 23 are provided on the glass plate 1 of the rear window, and the feeding points 21, 22 are fed between the feeding points 21, 23 and the feeding point 22, Three balanced signals between 23 are used.

Further, in the configuration example shown in FIG.
Two feeding points 21, 22, 23, and antenna conductors 24, 2 whose antenna conductors are connected to the feeding points 21, 22, 23
However, the number of feeding points may be three or more, and the number of antenna conductors may be increased as the number of feeding points increases.

In the present invention, as in the configuration example shown in FIG. 1, since at least one of the plurality of feeding points is connected to the other two feeding points via the antenna conductor, the antenna of the antenna conductor 24 is connected. Feed points 21, 2 using the effective length of
Between the feeding signal between the two receiving signals and the feeding points 22 and 23 using the effective length of the antenna of the antenna conductor 25, between the feeding points 21 and 23 using the effective length of the antenna of the sum of the antenna conductors 24 and 25 The received signal can be used, and space-saving and efficient reception can be performed. That is, when the number of feeding points is n, the maximum is (n-1) + (n-
2) Up to + ... + 1, the dipole antenna (dipole antenna) can be used.

It should be noted that the antenna conductor of the dipole antenna (FIG. 1) provided on the glass plate according to the present invention has about 0.7 times the spatial wavelength of the received radio wave (the shortening rate of the glass antenna).
Then, the antenna conductors 24 and 25 correspond to the antenna conductor length.

Further, according to the present invention, since a plurality of dipole antennas can be used, the directivity can be improved when the phases of the radio waves received by the dipole antennas are different. Even when the single pole antenna (single pole antenna) and the dipole antenna according to the present invention are used in combination, the phase difference between the plurality of dipole antennas and the single pole antenna can be used.

The balanced-unbalanced conversion circuit 2 shown in FIG.
6 is an antenna conductor 24 or 2 which is a dipole antenna.
It has a function of converting the balanced signal of No. 5 into an unbalanced signal and sending it to the selection circuit 27.

The selection circuit 27 is a balanced-unbalanced conversion circuit 2
6 has a function of selecting an appropriate one from a plurality of received signals sent from the terminal 6 and sending it to the television receiver 29 side.

The television amplifier 28 has a function of amplifying the received signal output from the selection circuit 27 and sending it to the television receiver 29. If the received signal output by the selection circuit 27 is strong, the television amplifier 28 is unnecessary.

In FIG. 1, the balanced-unbalanced conversion circuit 2
6, the selection circuit 27 and the television amplifier 28 are not separately integrated, but the balanced-unbalanced conversion circuit 26,
The selection circuit 27 and the television amplifier 28 may be integrated.

As the glass plate 1 for the rear window, usually a tempered glass of about 3 to 5 mm, a laminated glass or the like is used. An electrically heated defogger 3 having a large number of heater wires 2 and opposing bus bars 5a and 5b connected to both ends of the heater wire 2 group is provided in the heated area on the inner surface of the glass plate 1 of the rear window. Defogger 3 bus bar 5
Lead wires are connected to a and 5b.

The defogger 3 shown in FIG. 1 comprises a heater wire 2 and bus bars 5a and 5b. The heater wire 2 is usually made up of a large number of thin heater wires for electric heating having a width of 0.5 to 2 mm, which are arranged in parallel with each other in the horizontal direction on the glass plate.
It is formed with a space of 4 cm. further,
Bus bars 5a, 5 for supplying electric current to the heater wire 2
Form b on both sides of the heater wire 2. The heater wire 2 and the bus bars 5a and 5b 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.

In the case of FIG. 1, the antenna conductors 24 and 25 are provided in the margin above the defogger 3 of the glass plate 1. The antenna conductor 24 and the antenna conductor 25 are connected to each other in a DC manner because the feeding point 22 is common, but the antenna conductor 24,
25 may be close to each other at a predetermined interval in order to use each other as an antenna.

When they are brought close to each other, the antenna conductor 24 and the antenna conductor 25 do not transmit or receive a direct current between the antenna conductor 24 and the antenna conductor 25 at portions other than the feeding point 22, but do not transmit or receive a medium-high frequency current. Be combined. That is, in the present invention, the plurality of antenna conductors may be close to each other and capacitively coupled to each other. Also,
A single pole antenna may be included in these capacitively coupled antenna conductors.

The antenna conductor 24 or the antenna conductor 25 and the defogger 3 may be close to each other at a predetermined interval in order to improve the reception sensitivity by using the defogger 3 as an antenna. Due to the proximity, the antenna conductor 24 or the antenna conductor 25 and the defogger 3 are capacitively coupled so that the DC current is not transmitted and received therebetween, but the medium and high frequency currents are transmitted and received.

When the antenna conductor 24 or 25 and the defogger 3 are close to each other and capacitively coupled, the antenna conductor 24 or 25 and the defogger 3 are, for example, 0.2 to.
They are separated by an interval of about 50 mm. Due to this capacitive coupling, the defogger 3 apparently functions as a part of the antenna.

As described above, when the defogger 3 and the antenna conductors 24 and 25 are capacitively coupled at a part thereof, the defogger 3 and the antenna conductors 24 and 25 are usually the glass of the rear window. It is the same surface as the plate 1, and it is optimal to form it on the inner surface of the glass plate. The pattern of the antenna conductors 24 and 25 depends on the shape of the automobile, the shape of the glass plate, the dimensions, the configuration,
A pattern that can obtain optimum performance as an antenna for broadcasting, FM broadcasting, both radio broadcasting of AM broadcasting and FM broadcasting, or broadcasting for television or the like is appropriately selected and designed.

The position of the glass plate 1 on which the antenna conductors 24 and 25 are provided is shown in FIG.
Antenna conductor 2 in the margin above Defogger 3
Although the example in which Nos. 4 and 25 are provided is shown, the present invention is not limited to the position shown in FIG. 1 and may be a blank part below the defogger 3 of the glass plate 1. In addition, the defogger may be provided in the upper and lower margins, respectively, or in other margins. Further, another antenna conductor may be provided in the other blank portion where the antenna conductors 24 and 25 are not provided, and the function of the other antenna conductor may be the same frequency band as the antenna conductors 24 and 25. , Another frequency band may be used.

In the present invention, the antenna conductor length of each of the antenna conductors 24 and 25 is obtained by multiplying the target spatial wavelength of the received radio wave by the wavelength shortening rate (about 0.7) of the glass antenna.

Further, in FIG. 1, the antenna conductor 25 is not provided, and the defogger 3 may be used instead of the antenna conductor 25. In this case, if the structure shown in FIG. 1 is adopted, two feeding points corresponding to the feeding points 22 and 23 are attached to the defogger 3 and are connected to the feeding points corresponding to the feeding points 22. The antenna conductor
It is arranged so as to surround a power feeding point corresponding to the power feeding point 22.

In the present invention, when the antenna conductor according to the present invention and the defogger are capacitively coupled in part, a choke coil 9 is inserted between the bus bars 5a and 5b and the DC power source 10 for the defogger. By increasing the impedance of the choke coil 9 in the middle high frequency band, a direct current from the direct current power supply 10 to the defogger 3 is passed, but a current in the middle high frequency band such as various broadcasting frequency bands is cut off.

In this way, the choke coil 9 can insulate the heater wire 2 of the defogger 3 and the bus bars 5a, 5b from the vehicle body ground in the medium and high frequencies.
Also, it is possible to prevent the reception current in the middle and high frequency bands such as the broadcast frequency band induced in the bus bars 5a and 5b from flowing to the vehicle body ground, and to send this reception current to the receiver or the like without exception.

When the defogger 3 is used as an antenna, it receives only a high frequency band such as a television broadcast frequency band (hereinafter referred to as a TV band), an FM broadcast frequency band (hereinafter referred to as an FM band) and a UHF band. If you do
The choke coil 9 may be composed of only the high frequency coils 12a and 12b. Further, even when receiving both the medium wave band, the FM band and the TV band, if there is a coil that fulfills the functions of both the choke coil 9 and the high frequency coils 12a and 12b, the choke coil 9 is configured by only such coil. You may.

It is preferable that the choke coil 9 has a characteristic that it has a relatively high impedance in a medium and high frequency band such as a radio broadcast frequency band and prevents magnetic residual. For example, a high frequency choke coil bifilarly wound on a toroidal magnetic core (Mn-Zn ferrite or the like), a high frequency choke coil wound in a direction in which magnetic fluxes of the coils generated by a current from a closed magnetic circuit are canceled by each other, or a magnetic saturation degree A high frequency choke coil using a high core is exemplified.

Regarding the adjustment of the choke coil 9, in order to obtain the required inductance, self-resonant frequency and Q value, for example, the core is divided into two, the interval between the cores is adjusted, and a predetermined capacitor is connected in parallel. Adjustments are made by connecting or changing the coil pitch.

The capacitor 11 is electrically short-circuited with respect to a noisy current having a high frequency component (for example, a current mixed through a lead wire) in a medium and high frequency band such as a radio broadcast frequency band. Instead of providing the capacitor 11, a filter may be provided between the choke coil 9 and the DC power supply 10.

High frequency coil 12 in choke coil 9
a and 12b have high impedance at high frequencies such as TV band and FM band, and normally use solenoids or magnetic cores that do not use magnetic cores. These have inductive inductance near the TV band and FM band. Further, as the high frequency coils 12a and 12b, there may be a case where a lead wire having an appropriate length can be used, and further, the same effect may be obtained depending on the arrangement of the choke coil 9 in the vehicle body. The choke coil 9 is a TV
In the band and the FM band, the self-resonant frequency is low and the inductance is lost, so that the high frequency coils 12a and 12b substitute for this.

Next, the shapes of the antenna conductors, feeding points, etc. according to the present invention other than those shown in FIG. 1 will be described.
FIG. 2 is a front view of a shape of an antenna conductor, a feeding point, etc. according to the present invention different from that shown in FIG.

In FIG. 2, 31, 32, 33, 34,
35, 36, 37 and 38 are feeding points, 39 is a balanced-unbalanced conversion circuit and a selection circuit, 40 is a T-shaped auxiliary antenna conductor, and 41, 42, 43, 44, 45 and 46 are antenna conductors. These feed points and antenna conductors are provided on the glass plate of the window of the automobile.

The feeding points 31, 32, the feeding points 32, 33, the feeding points 33, 34, and the feeding points 35, 36 are a set of dipole antennas having common antenna conductors, and the feeding point 32 is the antenna conductors 41, 42. And the feeding point 33 is connected to the antenna conductors 42 and 43.

The feed point 37 is for a single pole antenna. The T-shaped auxiliary antenna conductor 40 attached to the antenna conductor 41 is for adjusting the phase, and is attached not only to the antenna conductor 41 but also to the antenna conductors 42, 43, 44, 45 or the defogger as necessary. The antenna conductor 41 may not be provided.

In FIG. 2, between the feeding points 31 and 32 and the feeding point 3
2, 33, feeding points 33, 34, feeding points 35, 36
Between the feeding points 31, 33, the feeding points 31, 34, and the feeding points 32, 34, respectively, of the balanced-unbalanced converted dipole received signal and the single-pole received signal of the feeding point 37. An appropriate received signal is selected by the selection circuit and used.

In FIG. 2, if necessary, the feeding point 38
Also, the antenna conductor 46 may be provided. Antenna conductor 4
When 6 is provided, there are three feeding points directly connected to the feeding point 32: the feeding point 31, the feeding point 33, and the feeding point 38. Further, by extending this idea, in the present invention, even if a plurality of antenna conductors constituting the dipole antenna are connected to one feeding point so that a plurality of feeding points are connected to one feeding point. Good.

As described above, according to the present invention, as shown in FIG. 2, the received signal between the feeding points of the dipole antenna having the feeding point in common with the other dipole antenna and the dipole antenna having the feeding point not in common with the other dipole antennas. The reception signal between the feeding points and the reception signal of the feeding point 37 related to the single pole antenna may be selectively used. In this case, the number of dipole antennas that do not share a feeding point with other dipole antennas is not limited to one, and there may be a plurality of dipole antennas. Further, the number of single pole antennas is not limited to one, and there may be a plurality.

The feeding points 35 and 36 which do not share the antenna conductor with other dipole antennas and the feeding point 37 related to the single pole antenna are provided as needed, and may not be provided in some cases. In addition, each antenna conductor 41, 42, 43, 44, 45, 4
Each of 6 may be close to each other and capacitively coupled, if necessary.

Further, the defogger may be used as a dipole antenna instead of the antenna conductor 44, and the defogger may be used as a single pole antenna instead of the antenna conductor 45. In this case, the antenna conductors 44 and 45 are provided separately from the defogger.
One or more antenna conductors corresponding to the above may be provided.

FIG. 3 is a front view of a shape of an antenna conductor, a feeding point, etc. according to the present invention, which is different from the examples of FIGS. 1 and 2.
In FIG. 3, parts having the same numbers as in FIG. 2 have the same names.

FIG. 4 is a front view of the shape of the antenna conductor, the feeding point and the like having the same shape as that shown in FIG. In FIG. 4, 241 is a change pattern of the antenna conductor 24, 39 is a balanced-unbalanced conversion circuit and a selection circuit, a,
b, c and d are distances.

In FIG. 4, the antenna conductor 24 connected to the feeding point 22 is arranged so as to surround the feeding point 21,
The antenna conductor 24 is further extended and connected to the feeding point 21. That is, an antenna conductor connected to at least one of the plurality of feeding points is arranged so as to surround another feeding point, and this antenna conductor is further extended and connected to the other feeding point. . By adopting such a pattern configuration, it is possible to maximize the effective length of the antenna in a space-saving manner and achieve compactness.

The arrows shown on the antenna conductors 24 and 25 indicate the direction of a current at a certain moment, and the antenna conductors 24 and 25 are arranged so that the adjacent portions have the same phase current.
Was arranged. As a result, the magnetic fluxes are summed, and the reception sensitivity is improved. The effect is exhibited when the distance a which is the interval between adjacent portions is about 50 mm or less, and the shorter the distance a, the higher the reception sensitivity.

Further, the modification pattern 2 of the antenna conductor 24
As shown by 41, a part of the left loop of the antenna conductor 24 is extended to the lower left, the change pattern 241 is brought close to the defogger 3, and the change pattern 241 is changed to the defogger 3.
May be capacitively coupled with.

Further, the change pattern 241 may be brought close to the antenna conductor 25 to capacitively couple the change pattern 241 with the antenna conductor 25 to enhance the capacitive coupling between the antenna conductor 24 and the antenna conductor 24.

FIG. 5 shows an example of the balanced-unbalanced conversion circuit 26 shown in FIG. In FIG. 5, 27
Is a selection circuit. The balanced-unbalanced conversion circuit in FIG. 5 is a Δ connection of three coils, and an unbalanced signal is obtained from the midpoint of each coil.

In the Δ connection of the three coils in FIG. 5,
The received signals of the antenna conductors 24 and 25 are converted into an unbalanced type by each coil to be OUT1 to OUT3. Each coil is a kind of differential transformer, and by extracting the difference signal of the received signal (balanced type) appearing between the feeding points having a certain impedance from the ground, it becomes an unbalanced signal at OUT1 to OUT3.

The signal taken out from the feeding point 22 which is the midpoint between the antenna conductors 24 and 25 is OUT4. Each coil may be an air core, or may be produced by winding a coated copper wire or the like on ferrite or the like.

OUT1 to OUT3 were taken out from the midpoint of each coil. OUT1 and OUT2 are mainly for VHF-high band reception, and OUT3 are mainly for VHF-low band reception.

Further, FIG. 6 shows a circuit diagram of an example of the balanced-unbalanced conversion circuit 26 in FIG. 1 different from FIG. Figure 6
In the figure, 27 is a selection circuit. Equilibrium in FIG.
The unbalanced conversion circuit has a Δ-Y connection, and an unbalanced signal is obtained from the Y connection of the secondary coil. The balanced-unbalanced conversion circuit according to the present invention is not limited to those shown in FIGS. 5 and 6, and any circuit having a necessary balance-unbalanced conversion function can be used. In addition, the balanced-unbalanced conversion circuit according to the present invention is not limited to the Δ-Y connection shown in FIG.
-△ connection, Y- △ connection, Y-Y connection can also be used.

[0060]

Embodiments will be described below with reference to the drawings.

Example 1 An automobile glass antenna system shown in FIG. 1 was prepared. Antenna conductors 24, 25
Is for receiving VHF TV broadcasts. Figure 4 as above
4 is an enlarged view of FIG. 1, and in Example 1, the distance a shown in FIG.
Is 10 mm, the distance b is 465 mm, the distance c is 10 mm,
The distance d was 505 mm. Therefore, the antenna conductors 24 and 25 are capacitively coupled. Further, the antenna conductor 25 and the heater wire 2 are capacitively coupled, and as a result,
The antenna conductor 24 and the defogger 3 are indirectly capacitively coupled.

In the first embodiment, the antenna conductor lengths of the antenna conductor 24 and the antenna conductor 25 are both 1050.
mm. The reason for doing this is as follows:
Spatial wavelength 1 of the central frequency (200 MHz) in the high band
This is because the conductor lengths of the antenna conductor 24 and the antenna conductor 25 match the value obtained by multiplying 500 mm by the wavelength shortening rate of 0.7 on the glass surface. As a result, the antennas between the feeding points 21 and 22 and between the feeding points 22 and 23 are VHF.
-Resonates in the high band.

Further, in the antenna conductor between the feeding point 21 and the feeding point 23, the length of the antenna conductor is doubled, which is 100
Resonates at MHz (VHF-low band). OUT1 and OUT2 are mainly for receiving VHF-high band, and OU
T3 is mainly for VHF-low band reception.

FIG. 7 is a characteristic diagram of the receiving sensitivity-frequency of the conventional example shown in FIG. 1 and FIG. 8, which is represented by the gain of the dipole antenna ratio. In both Example 1 and the conventional example, the amplification in the latter stage of the antenna itself was set to 3 dB, and the same conditions were set, and other conditions such as using the same automobile were set to the same conditions. In the first embodiment, diversity data of four outputs (OUT1 to 4) using the antenna conductors 24 and 25 is displayed, and in the conventional example shown in FIG. 8, diversity data of four antennas is displayed. From FIG. 7, the receiving sensitivity of the first embodiment is 90 to 770 MHz more than the receiving sensitivity of the conventional example shown in FIG.
It can be seen that it is several dB higher than that.

(Embodiment 2) In Embodiment 2, the antenna conductor 24 has an antenna conductor length of a resonance frequency of 180 MHz (1167 mm on the glass plate surface).
By setting the conductor length of No. 5 to a length that resonates at 220 MHz (955 mm on the glass plate surface), a broadband VHF can be obtained.
The -high band can be frequency-divided and covered by OUT1 and OUT2 shown in FIG. Even in this case, OUT3
Output resonates at about 100 MHz, which is similar to the first embodiment in this respect. The other conditions were the same as in Example 1. In Example 2 as well, it was several dB higher than the receiving sensitivity of the conventional example shown in FIG. 8 in the range of 90 to 770 MHz.

(Third Embodiment) In the third embodiment, the antenna conductor lengths of the antenna conductor 24 and the antenna conductor 25 are set to the second embodiment.
The other conditions were the same as in Example 2.

However, the antenna conductor 24 shown in FIG. 4 is of a type like the change pattern 241. The distance between the change pattern 241 and the heater wire 2 is 10 mm, the distance between the change pattern 241 and the antenna conductor 24 is also 10 mm, the antenna conductor 24 is capacitively coupled to the heater wire 2, and the antenna conductor 24 and the antenna conductor 25 are connected to each other. Strengthened capacitive coupling. As a result, the receiving sensitivity of the third embodiment is 1 to 90 at 770 MHz than the receiving sensitivity of the second embodiment.
It was 2 dB higher.

[0068]

According to the present invention, at least one of a plurality of feeding points is connected to two or more other feeding points via respective antenna conductors, and is selected from the plurality of feeding points. It is possible to utilize the received signal of each set of the two feeding points. That is, when the number of feeding points is n,
The dipole antenna can be used up to the maximum number of (n-1) + (n-2) + ... + 1. Therefore, space-saving and efficient reception are possible.

Therefore, an antenna conductor for other purposes can be provided in the margin of the glass plate of the window other than the area where the antenna conductor and the feeding point according to the present invention are provided, which is suitable for diversification of broadcasting. The antenna system can be completed.

Further, according to the present invention, impedance matching can be easily performed. For example, in the case of TV broadcast reception,
Since the balanced reception signal appearing between the feeding points can be converted into the 75 Ω unbalance which is the input impedance of the television (the television amplifier when the television amplifier is used), the reception signal can be efficiently transmitted to the television.

Further, since it is often possible to obtain received signals having different phases from the plurality of antenna conductors according to the present invention, improvement of directivity can be easily achieved.

Further, when the frequency band to be received is a wide band, even if an attempt is made to receive all frequency bands with a constant reception sensitivity, a great number of tuning steps are not required and it can contribute to the improvement of productivity. The effect is also recognized.

[Brief description of drawings]

FIG. 1 is a typical example of a glass antenna for an automobile of the present invention.
FIG.

FIG. 2 is a front view of shapes of an antenna conductor, a feeding point, and the like according to the present invention, which are different from those shown in FIG.

FIG. 3 is a front view of shapes of an antenna conductor, a feeding point, and the like according to the present invention, which are different from those shown in FIGS. 1 and 2.

FIG. 4 is a front view of shapes of an antenna conductor, a feeding point, and the like having the same shape as that shown in FIG.

FIG. 5 is a circuit diagram of a conversion circuit.

FIG. 6 is a circuit diagram of an example of a balanced-unbalanced conversion circuit different from that of FIG.

FIG. 7 is a characteristic diagram of reception sensitivity-frequency in the example and the conventional example.

FIG. 8 is a configuration diagram of a conventional glass antenna for an automobile.

[Explanation of symbols]

 1: Glass plate of rear window of automobile 2: Heater wire 3: Defogger 5a, 5b: Bus bar 9: Choke coil 10: DC power supply 11: Capacitor 12a, b: High frequency coil 21, 22, 23: Feeding point 24, 25: Antenna conductor 26: Balance-unbalance conversion circuit 27: Selection circuit 28: TV amplifier 29: TV receiver

Claims (4)

[Claims] 1. A plurality of feed points for a dipole antenna, and a plurality of antenna conductors respectively connected to these feed points and functioning as dipole antennas are provided on a glass plate of a window of an automobile, and these antennas are further provided. A balanced-unbalanced conversion circuit for converting a balanced signal of a conductor into an unbalanced signal, and a selection circuit for selecting an appropriate received signal, at least one of a plurality of feeding points being at least two other feeding points. Are connected to each other via antenna conductors, and the balanced signal of the received signal of each pair of two feeding points selected from a plurality of feeding points is converted into an unbalanced signal by the balanced-unbalanced conversion circuit. A glass antenna for an automobile, characterized in that an appropriate received signal is selected from the received signals converted into the signal by a selection circuit and used. 2. The glass antenna for an automobile according to claim 1, wherein at least one of the plurality of antenna conductors is capacitively coupled to another antenna conductor. 3. An antenna conductor connected to at least one of a plurality of feeding points is arranged so as to surround another feeding point, and the antenna conductor is further extended and connected to the other feeding point. The glass antenna for an automobile according to claim 1 or 2, characterized in that 4. At least one of the plurality of antenna conductors is adjacent to an electrically heated defogger having a heater wire provided on a glass plate of a rear window of an automobile and a bus bar for feeding the heater wire, DC current is not sent to and received from the defogger, but high frequency current is sent and received capacitively, and choke coils are connected between one bus bar and the battery and between the other bus bar and ground. The insertion connection is made, and
2 or 3 glass antennas for automobiles.