JPH0235482B2 - SHARYOYOGARASUANTENA - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a glass antenna for a vehicle that is attached to the rear window of a vehicle, and particularly to one that receives radio waves in the medium wave and very high frequency radio frequency bands.

[Prior Art] In vehicles such as automobiles, glass antennas provided on windshields (particularly rear windows) have been used. This vehicle glass antenna uses a defogger hot wire normally installed in the windshield as an antenna, and supplies the received radio waves to a radio receiver such as an FM radio for very short waves or an AM radio for medium waves.

Here, such a conventional glass antenna for a vehicle will be explained based on FIG. 1. In FIG. 1, a main element 2 of a glass antenna is arranged with a predetermined width on the upper part of a windshield glass 1 constituting a window such as a rear window of a vehicle. The main element 2 outputs received radio waves from a power feeding point (terminal) 3 provided at its center.

On the other hand, a defogger heating wire 4 is provided at a location a certain distance away from the main element 2.

Note that the power feeding point 3 of the main element 2 mentioned above is
It is connected via an antenna feed line 5 to a receiver 6 consisting of an AM radio for medium waves, an FM radio for very short waves, etc., and the received radio waves are reproduced in these receivers 6.

The defogger hot wire 4 has its current supply terminal 4a,
Power supply wires 7a and 7b connected to 4b are connected. And this power supply wire 7a,
7b is connected to the battery 9 and the ground via a noise prevention coil (impedance converter) 8, respectively. Therefore, the current from the battery 9 flows through the choke coil 8, the power supply wire 7a,
The current flows to the ground via the current supply terminal 4a, the defogger hot wire 4, the current supply terminal 4b, the power feeding wire 7b, and the choke coil 8, and can generate a predetermined amount of heat in the defogger hot wire 4.

Here, the chiyoke coil 9 not only prevents noise but also
By increasing the impedance on the side of the chiyoke coil 8 seen from the current supply terminals 4a and 4b, the receiver 6
Power supply wires 7a, 7 in case of AM receiver
Prevent the influence of wiring b. That is, without the chi-yoke coil 8, the electromotive force induced in the defogger hot wire 4 by the received radio waves would escape to the battery 9 and the ground side via the power supply wires 7a and 7b, and the received waves in the AM band would be Sensitivity will drop significantly. However, when the chiyoke coil 8 is inserted and arranged, the power supply lines 7a and 7b seen from the defogger hot wire 4 are
By increasing the impedance on the side, the electromotive force induced in the defogger hot wire 4 can be prevented from escaping.

Note that although the defogger hot wire 4 is not directly connected to the main element 2, since the two are placed facing each other with a certain distance between them, the two are connected in terms of high frequency. Therefore, the defogger hot wire 4 can contribute to radio wave reception in the main element 2 due to the mutual induction effect.

In this manner, in the conventional glass antenna for a vehicle, the defogger hot wire 4 not only performs a predetermined defogger function, but also contributes to improving antenna performance. In addition, the glass antenna using the defogger hot wire 4 includes the defogger hot wire 4 in addition to the main element 2.
etc. as the antenna element, the defogger hot wire 4
In order to efficiently accept the electromotive force induced by the antenna element 2, the size and other specifications of the antenna element 2 are tuned to achieve omnidirectionality.

[Problems to be Solved by the Invention] However, if the receiver 6 is configured to receive radio waves in two different frequency bands, such as AM radio and FM radio, the received waves of FM radio, etc. The problem was that it could not demonstrate sufficient performance when receiving frequencies in the VHF (very high frequency) band.

That is, in the case of medium waves received by AM radio, the influence of external noise can be reduced by the chiyoke coil 8. However, in the case of VHF (very high frequency) received by FM radio, even if you consider only the glass antenna as an antenna and tune it to obtain omnidirectionality, the feeding wire 7
A and 7b operate as a kind of antenna, which has problems such as introducing external noise and impeding the omnidirectionality of the antenna. This is because the power supply wires 7a and 7b directly pick up external noise, and the overall tuning balance including the main element 2 mentioned above is disrupted due to the length and placement of the power supply wires 7a and 7b. This is because omnidirectionality may not be achieved. Therefore, it is conceivable to tune the power supply wires 7a and 7b together, but even in such a case, due to variations in the wiring of the power supply wires 7a and 7b in each vehicle during mass production of vehicles, There was a problem that the antenna performance varied.

Here, the current supply terminal 4a of the defogger hot wire 4,
If 4b is grounded at a high frequency, it is possible to eliminate the negative influence of the feeding wires 7a and 7b on ultra-high frequency reception, but with this configuration, the performance as an antenna for medium wave reception for AM radio will be significantly degraded. become. That is, in the glass antenna, the electromotive force induced in the defogger hot wire 4 is also used for reception, but if the current supply terminals 4a and 4b are grounded, the induced voltage generated in the defogger hot wire 4 will be grounded. This is because it becomes impossible to use it effectively. In addition, in this way, the current supply terminals 4a, 4b
The reason why the antenna sensitivity to medium waves decreases significantly due to grounding is that the wavelength of medium waves is much longer than the width of the glass antenna, so antenna sensitivity is proportional to the area of the entire antenna element. However, since the wavelength of very short waves is short, it mainly depends on the length of the antenna element.

The present invention has been made to solve the above-mentioned conventional problems, and even when receiving radio waves in different radio frequency bands, it is possible to receive radio waves with high sensitivity without adversely affecting antenna performance. The purpose of the present invention is to provide a glass antenna for vehicles.

[Means for Solving the Problems] The first invention provides medium wave and For vehicles, comprising a main element connected to an ultra-high frequency receiver, and a pair of power supply wires, one end of which is connected to a pair of current supply terminals of the defogger hot wire, and the other end of which is connected to a power source via an impedance converter. In the glass antenna, each wire is wired along the pair of power supply wires, one end is connected to the current supply terminal of the defogger hot wire, the other end is open, and the length thereof corresponds to the reception wavelength λ of the ultrashort wave receiver. a pair of open stub wires set to approximately 1/4 times the width of the antenna, and the open stub wires form a stub for the power feeding wire during ultra-high frequency reception. .

In a second invention, instead of providing the open stub wire, the length of the pair of power feeding wires from the current supply terminal to the impedance converter is set to approximately 1/4 times the receiving wavelength λ of the very high frequency receiver. and thereby form a stub for the power feeding wire during ultra-high frequency reception.

[Function] According to the first invention, the open stub wire wired along the power supply wire acts as a stub for the power supply wire during ultra-high frequency reception, and the connection portion of the power supply wire to the defogger hot wire is The impedance can be lowered at the current supply terminal. Therefore, the defogger heating wire can be considered to be grounded at high frequency at its current supply terminal, and it is necessary to prevent the wiring or twisting of the power supply wire from having an adverse effect on the FM receiver. Can be done.

According to the second invention, the length of the power supply wire from the current supply terminal to the impedance converter is set to approximately 1/4 times the reception wavelength of the ultra-high frequency receiver, so that the current supply terminal of the defogger hot wire is The impedance at can be reduced. That is, according to the second invention, the stub can be formed by the power feeding wire itself. Therefore, as in the first invention, it is possible to prevent an adverse effect on the FM receiver.

[Example] Hereinafter, an example of a glass antenna for a vehicle according to the present invention will be described based on the drawings. FIG. 2 is a configuration diagram of a glass antenna for a vehicle according to the present invention. Note that the same members as in the conventional example shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, current supply terminals 4a, 4b
While connecting the power supply wires 7a and 7b to the
In addition to this, open stub wires 10a and 10b whose tips are open are connected. That is, one end of an open stub wire 10a is connected to the current supply terminal 4a to which the power supply wire 7a is connected, and this open stub wire 10a is separated from the power supply wire 7a by a substantially constant distance and runs along the current supply terminal 4a. They extend parallel to each other and are open at the other end.

Further, the open stub wire 10b connected to the current supply terminal 4b, which is the connection end of the power supply wire 7b, is wired substantially parallel to the power supply wire 7b, as in the above case.

In this embodiment, the length ls of the open stub wires 10a and 10b is set to approximately 1/4 of an arbitrary reception wavelength λ within the reception band of very short waves, for example, FM radio, in the receiver 6.
For example, the frequency used for FM radio broadcasting is around 80MHz, so it is 1/1/1 of the receiving wavelength λ.
The length of 4 is approximately 90cm. Therefore, the length ls of the open stub wires 10a and 10b may be set to approximately this length. If the length of the open stub wires 10a and 10b is set to about 1/4 of the receiving wavelength λ, then the wavelength λ
When a long radio wave is received, the current supply terminal 4, which is the connection end of the open stub wires 10a and 10b,
The impedance at a and 4b becomes minimum.
That is, open stub wires 10a, 10b
By connecting these, you can achieve the same result as connecting bypass capacitors in parallel in an electrical circuit to minimize the impedance at the connection point.

Here, open stub wires 10a, 10b
The operation will be explained based on FIG. FIG. 3 shows the combined impedance of the open stub wires 10a, 10b and the power supply wires 7a, 7b viewed from the current supply terminals 4a, 4b.
It is a characteristic diagram showing the result of measuring up to the length ls of a and 10b. In the figure, the vertical axis represents the combined impedance, and the horizontal axis represents the distance from the current supply terminals 4a, 4b.

As is clear from FIG. 3, the combined impedance is minimum at the current supply terminals 4a, 4b, and increases as the distance from the current supply terminals 4a, 4b increases. From this, by connecting the open stub wires 10a, 10b to the current supply terminals 4a, 4b, the current supply terminals 4a, 4
It is understood that the impedance at b can be reduced, and in this respect, the same effect as grounding at high frequencies can be obtained. By reducing the impedance at the current supply terminals 4a and 4b in this way, the defogger heating wire 4 is connected to the power supply wire 7.
The voltage induced by the ultrahigh frequency waves can be supplied to the main element 2 without being affected by the components a, 7b, etc.

Further, it is possible to prevent an adverse effect on ultra-high frequency reception caused by wiring, twisting, etc. of the power feeding wires 7a, 7b. In addition, the current supply terminals 4a, 4
The impedance at b has such a value that it is considered to be grounded in terms of high frequency with respect to any frequency in the ultra-high frequency reception frequency band.

Note that the radio waves in the medium wave receiving frequency band for AM radio have a wavelength approximately 100 times that of ultra-short waves, and the open stub wires 10a and 10b
In some cases, a stub is not formed, and since the chiyoke coil 8 has a sufficiently high impedance for this radio wave, the open stub wire 1
The presence of 0a and 10b can be ignored, and no adverse effect on medium wave reception occurs.

In the embodiment described above, open stub wires 10a, 10b are provided, and current supply terminals 4a, 4
Although the impedance at b is lowered, the same effect can be produced even without providing the open stub wires 10a and 10b.

That is, open stub wires 10a, 10
Instead of providing the power supply wires 7a and 7b, the length of the power supply wires 7a and 7b is set to 1/4 of the receiving wavelength λ of the very short wave for FM radio.
When set to , the power supply wires 7a, 7b themselves function as stubs, and the current supply terminals 4a, 4b
It is possible to lower the impedance of the If the length of the power supply wires 7a, 7b is set to about 1/4 of the receiving frequency λ of the ultra-short wave, the impedance characteristics of the power supply wires 7a, 7b will be approximately the same as the impedance characteristics shown in FIG. It will be about the same level. Therefore, it is possible to obtain the same effects as in the above-described embodiment.

Furthermore, if the receiver 6 is equipped with an amateur radio device in addition to an AM radio for medium wave reception,
This frequency is similar to ultra-high frequency for FM radio, and the open stub wires 10a and 10b
Alternatively, the same effect as described above can be obtained by setting the length of the power feeding wires 7a, 7b to about 1/4 of the receiving or transmitting wavelength of the frequency used in this amateur radio device.

Moreover, if the open stub wires 10a and 10b are provided and the length of the power supply wires 7a and 7b from the current supply terminal to the impedance converter is set to 1/4 of the receiving wavelength λ of the ultrashort wave,
Very effective very high frequency reception can be achieved.

[Effects of the Invention] As explained above, according to the present invention, since the length of the open stub wire or the power feeding wire is set to about 1/4 of the wavelength λ of the received very short wave, it can be used for medium waves such as AM radio and FM. It is possible to receive both very short waves such as radio waves with high sensitivity.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional glass antenna for a vehicle, Fig. 2 is a block diagram of a glass antenna for a vehicle according to the present invention, and Fig. 3 is an impedance characteristic of the open stub wire shown in Fig. 2. FIG. 1... Windshield glass, 2... Main element, 3... Feeding point, 4... Defogger hot wire, 5... Antenna feeding line, 6... Receiver, 7a, 7b... Feeding wire, 8... Chiyoke coil (impedance converter), 9 ...Battery, 10a, 10b...Open stub wire.

Claims (1)

[Scope of Claims] 1. A defogger hot wire provided on a windshield; and a main body provided on the windshield at a certain distance from the defogger hot wire and connected to a medium wave and very high frequency receiver via a power supply line. A glass antenna for a vehicle, comprising: an element; and a pair of power supply wires, one end of which is connected to the pair of current supply terminals of the defogger hot wire and the other end of which is connected to a power supply and ground via an impedance converter, One end is connected to the current supply terminal of the defogger heating wire, the other end is open, and the length thereof is approximately 1/4 times the receiving wavelength λ of the ultra-short wave receiver. A glass antenna for a vehicle, comprising: a pair of open stub wires set to , and the open stub wires forming a stub of the power feeding wire during ultra-high frequency reception. 2. A defogger hot wire provided on the windshield; a main element provided on the windshield at a certain distance from the defogger hot wire and connected to the medium wave and ultra-high frequency receiver via a power supply line; A glass antenna for a vehicle comprising a pair of power supply wires connected to a pair of current supply terminals of a defogger hot wire, and the other end of which is connected to a power source and a ground via an impedance converter, the above of the pair of power supply wires. The length from the current supply terminal to the impedance converter is set to approximately 1/4 times the receiving wavelength λ of the very short wave receiver,
A glass antenna for a vehicle, characterized in that this forms a stub for the power feeding wire during ultra-high frequency reception.