JPH0375090B2 - - 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 pick-up coil wound around the ferrite core and connected to the glass antenna element;
It is characterized by having the following.

[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, an antenna element 12 made of copper foil or the like is printed in the same pattern on a vehicle glass (for example, a front windshield glass) 10 symmetrically with respect to the center of the vehicle. In addition, the inner surface (vehicle interior side) of the vehicle body outer plate 14 as the vehicle body wall near the feeding point of the antenna element 12
A recess 13 is formed in the recess 13, and a ferrite core 16 is embedded in the recess 13 in the vehicle width direction, and a pickup coil 18 connected to the antenna element 12 is wound around the ferrite core 16. . A series-connected capacitor 20 and a variable capacitor 22 such as a variable capacitor, a variable capacitance diode, etc. are connected in parallel to the pickup coil 18 for tuning to the broadcast wave to be received. Another pickup coil 24 is wound around the ferrite core 16, one end of which is grounded to the vehicle body, and the other end connected to an impedance converter 26 and a coaxial cable 28.
to a receiver (not shown). The vehicle body outer panel 14 is composed of a conductive iron plate 14a and a coating layer 14b formed on both surfaces thereof, and the ferrite core 16 is buried so as to be in contact with the conductive iron plate 14a.

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

When a vehicle enters a place where radio waves to be received exist, a current induced in the antenna element 12 by the radio waves flows through the pick-up coil 1.
8 and tuning capacitors 20, 22 to collect the magnetic flux into the ferrite core 16. In addition, the vehicle body outer plate 1
In order to embed the ferrite core 16 in 4,
A slit 30 provided on the inner surface of the vehicle body outer panel 14 traps the induced magnetic flux induced in the vehicle body outer panel 14 by the broadcast radio waves. The induced current corresponding to this trapped magnetic flux is efficiently extracted by the pickup coil 24 and transmitted to the receiver via the impedance converter 26 and coaxial cable 28. In this case, the pick-up coil 24
The figure-of-eight directivity characteristic can be made non-directional by changing the specifications of the antenna element 12 on the glass surface, and the induced current in the vehicle body outer panel 14 and the induced current formed in the antenna element 12 can be made non-directional by changing the specifications of the antenna element 12 on the glass surface. By combining with the pick-up coil 18,
A highly sensitive car body antenna can be constructed.

FIGS. 2 and 3 show diagrams of the vehicle mounting state of the first embodiment. FIG. 2 shows an example in which a vehicle body antenna is mounted by providing an antenna element 12 on the front windshield glass 10 and embedding a ferrite core 16 in the center of the vehicle. Although not shown in the drawings, the antenna element 12 may have the same structure as the antenna element 12 on the back windshield, and a vehicle body antenna may be provided on the outer panel of the vehicle body in the vicinity thereof. FIG. 3 shows an example in which a vehicle body antenna is provided in the front pillar portion, and antenna elements 12 are provided in the upper and lower portions of the front windshield glass.

Note that the ferrite core 16 in the first embodiment
may be air-core or dielectric.
Further, in the first embodiment, the pick-up coil is
However, a configuration in which a tap is taken out from the pick-up coil 18 and connected directly from the tap with a coaxial cable may also be used.

FIG. 4 shows a second embodiment, in which an unbalanced power supply system is adopted, and the pick-up coil 18 is one, and the other end of the pick-up coil 18 is connected to the vehicle body outer panel 14 via a connecting wire 32. The second embodiment differs from the first embodiment in that the second embodiment is different from the first embodiment, and the operation is the same as the first embodiment. The advantage of the configuration of the second embodiment is that the antenna element 12 can be formed in one stroke, which reduces costs, and
The point is that only one pick-up coil 18 is required.

Figures 5 and 6 show the state in which the second embodiment is mounted on a vehicle, with Figure 5 being an example installed on a vehicle body under the same conditions as Figure 2, and Figure 6 being the same as Figure 3. These applications are all the same as those described in the first embodiment.

[Effects of the Invention] As described in detail above, according to the present invention, since there is no protrusion on the surface of the vehicle body, all the inconveniences that occur when a large number of conventional pole antennas are arranged side by side are eliminated. Further, the best reception performance is always ensured with high sensitivity, and effects such as omnidirectionality can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the first embodiment of the present invention, FIGS. 2 and 3 are vehicle mounting state diagrams of the first embodiment, FIG. 4 is a block diagram showing the second embodiment, and FIG. , FIG. 6 is a diagram of the vehicle mounting state of the second embodiment. 10...Glass, 12...Antenna element, 14...Vehicle body outer plate, 16...Ferrite core, 18, 24...Pickup coil.

Claims (1)

[Claims] 1. A ferrite core embedded in the car body wall so as not to form a protrusion on the outer surface of the car body so as to collect magnetic flux based on induced current induced in the car body by received radio waves, and a glass antenna element wrapped around the ferrite core. 1. A vehicle antenna device comprising: a pick-up coil connected to a pickup coil;