JPH0375091B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle antenna device, and particularly to a vehicle antenna device that uses a vehicle body as a part of the antenna.

BACKGROUND ART Conventionally, pole antennas have been mainly used as vehicle antenna devices. On the other hand, vehicles are equipped with a variety of onboard wireless devices such as radios, televisions, personal radios, and telephones, and a vehicle equipped with all of these wireless devices requires a large number of pole antennas. This will cause such inconvenience.

Deterioration of reception performance due to deterioration of each antenna performance due to mutual interference between pole antennas (for example, gain decrease due to impedance change, directivity deterioration, etc.).

Negative impact on vehicle design due to overcrowding of pole antennas.

It is extremely difficult to take measures against wind noise, which is an essential drawback of antennas that protrude outside the car body, damage to pole antennas due to mischief, theft, and sliding parts that become stuck due to intrusion of dirt or dust, etc.

When washing the car, parking it in the garage, etc., it is necessary to store or remove the pole antenna, resulting in poor operability.

Purpose of the Invention The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a vehicle antenna device that eliminates all the conventional disadvantages and can always ensure the best reception performance. .

Composition of the Invention In order to achieve the above object, the present invention provides a structure that is embedded in a car body wall without forming a protrusion on the outer surface of the car body so as to collect magnetic flux based on an induced current induced in the car body by received radio waves. Ferrite core and
a pickup coil for resonance and a pickup coil for reducing mismatch loss, which are wound around the ferrite core so that an induced current is induced based on the magnetic flux collected in the ferrite core; The vehicle is characterized in that it has a connection line that connects the pickup coil to the vehicle body wall.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention. In Fig. 1, a car body outer plate 1 as a car body wall
A recess 12 having an arbitrary width and length is formed in an arbitrary part of the inner surface (inside the passenger compartment) of the vehicle 0, and a ferrite core 14 is embedded in the recess 12. Since the car body outer plate (conductor iron plate) 10 has coating layers 16 and 18 on the inner and outer surfaces, the ferrite core 14 is coated with the car body outer plate 1.
0 is inserted and buried in the recess 12 so as to be in contact with the recess 12. A pick-up core 20 is wound around the ferrite core 14, and both ends thereof are connected to the vehicle body outer panel 10 via lead wires 22 and 24. Further, a capacitor 26 and a variable capacitance diode 28 connected in series are connected in parallel to both ends of the pickup coil 20 so as to be tuned to the receiving frequency. Further, high frequency choke coils 30 and 32 are connected to both ends of the variable capacitance diode, and a lead wire 3 is connected to the variable capacitance diode 28.
4 and 36 to supply a DC control voltage for changing the capacitance. Another pickup coil 38 whose output impedance is not particularly specified is wound around the ferrite core 14. One end of this pickup coil 38 is connected to an impedance converter (including an amplifier) 40, and the other end is connected to a coaxial cable. It is grounded to the vehicle body connected to the ground external wire 42a of No. 42. The impedance converter 40 has an output impedance of 50Ω, and the core wire 4 of the coaxial cable 42
2b, coaxial cable 42, lead wire 3
4, 36 and an impedance converter lead wire (not shown) are taped and connected to the receiver.

The first embodiment of the present invention has the above configuration, and its operation will be explained below.

When a vehicle enters a location where radio waves to be received are present, the radio waves create an induced current in the vehicle body based on Maxwell's basic equation. The induced current formed in the vehicle body forms a magnetic flux near the recess 12. The magnetic flux is collected by the ferrite core 14, which is a magnetic material, and a high-density magnetic flux is formed. In this case, the vehicle body outer plate 10
If the distance between and the ferrite core 14 is large,
Since the magnetic resistance becomes large and sufficient magnetic flux cannot be collected, it is necessary that the two be brought into close contact with each other.
The magnetic flux collected on the ferrite core 14 causes the pick-up coil 2 to be wound around the ferrite core.
An induced current corresponding to the magnetic flux is formed at 0,38. The amount of induced current in the pick-up coil is determined by a circuit that tunes to the receiving frequency using a capacitor 26 and a variable capacitance diode 28, and a circuit that tunes the pick-up coil 20 to the receiving frequency.
Q of this resonant circuit is determined by parallel resonance with
(resonance magnification) times only is picked up. The resonant frequency of the tuned circuit can be changed by applying a DC voltage to the variable capacitance diode 28 via the high frequency choke coils 30, 32 and the power lines 34, 36 to vary the capacitance of the variable capacitance diode 28. be. On the other hand, the current induced in the pickup coil 38 is transferred to the impedance converter 40,
It is transmitted to a receiver via a coaxial cable 42.

In the above configuration, the induced current in the system connected to the vehicle outer panel 10 and the pickup coil 20 forms a magnetic flux in the ferrite core 14, changing the connection point of the pickup coil 20 to the vehicle outer panel 10. This allows the directivity to be changed, which has the advantage of increasing the degree of freedom in design.

Figure 2 shows tap 4 on the pick-up coil 20.
4 and connected to an impedance converter 40 to form a pickup coil 38, which has the advantage that the number of coils may be small.

[Effects of the Invention] As detailed above, according to the vehicle antenna device according to the present invention, since there is no protrusion on the vehicle body surface, all the inconveniences that occur when a large number of conventional pole antennas are arranged in parallel are eliminated. be done. Moreover, the antenna can always ensure the best reception performance. moreover,
By changing the connection point of the resonant pickup coil to the car body wall, the directivity can be changed and the degree of freedom in design can be increased.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a first embodiment of a vehicle antenna device according to the present invention, and FIG. 2 is a block diagram of a second embodiment. 10...Vehicle body outer plate, 12...Recess, 14...Ferrite core, 20, 38...Pickup coil.

Claims (1)

[Claims] 1. A ferrite core embedded in the car body wall without forming a protrusion on the outer surface of the car body so as to collect magnetic flux based on the induced current induced in the car body by received radio waves, and A resonance pick-up coil and a mismatch loss reduction pick-up coil are wound around the ferrite core so that an induced current is induced based on the ferrite core, and the resonance pick-up coil is connected to the car body wall to make the directivity variable. A vehicle antenna device comprising: a connection line;