JPS6219083B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a vehicle antenna capable of receiving AM broadcast radio waves, FM broadcast radio waves, and television (TV) radio waves. Multipath noise, picket fencing,
This is designed to reduce TV ghost and TV flutter phenomena.

Conventional vehicle antennas that are generally used include whip antennas, pillar antennas, wind seal antennas, and rain gutter-mounted antennas, but these have advantages and disadvantages.

That is, whip antennas, pillar antennas, and rain gutter-mounted antennas protrude outside the vehicle body, making them unsightly and dangerous. Further, they have drawbacks such as generating harsh wind noise when driving at high speeds and being easily damaged by tampering when parked. In addition, wind seal antennas have the disadvantage that the production cost is high because the antenna conductor is sealed or pasted on the windshield, and especially when the antenna is installed on the windshield, the antenna conductor may be exposed when driving. It may also obstruct visibility. Furthermore, when an antenna conductor is attached to the rear window glass, there are restrictions on the shape of the antenna, and the cable to the receiver becomes longer, resulting in a decrease in gain.

In addition, since reception is conventionally performed using a single antenna, multipath interference and picket fencing are likely to occur when receiving FM broadcasts, and TV ghosts and flutter phenomena are likely to occur when receiving TV broadcasts.

The present invention solves the above-mentioned drawbacks and problems.

FIG. 1 is an external view of an actual vehicle implementing an example of the present invention. As shown in the figure, side visors 1 and 1' are attached to both sides of an automobile 100.

The side visors 1, 1' are made of an insulating material such as plastic, and a linear or foil conductor 2, 2' is provided inside the visor 1, 1' in a molded or pasted state, and the conductor 2, 2' is used as an antenna. That's what I do.

By doing so, excellent effects can be achieved in terms of both appearance and safety.

FIG. 2a illustrates the side visor mounted antenna of FIG. 1 according to the present invention. In this antenna, a dipole antenna element 2a corresponding to the conductors 2 and 2' is attached to the side visor 1, and its directivity becomes unidirectional due to the reflection effect of the vehicle body, as shown in FIG. 2b. This is due to multipath interference in FM reception and TV broadcasting, which will be explained later.
Effective against ghosts. Note that a and a' are power feeding points.

FIG. 3 shows an example in which a unipole antenna element 4 corresponding to the conductors 2 and 2' is attached to the side visor 1 in the same way as in FIG. car 100
It is configured as a vehicle body a′. After all, a single directivity can be obtained due to the reflection effect of the vehicle body.

FIG. 4 shows an antenna conductor 5 attached to the side visor 1 in the same way as in FIG. There is. The impedance of this antenna acts like a loop antenna, but the directivity characteristic is unidirectional as in the previous example.

By attaching the antenna conductor to the side visor as described above, there are no protrusions and the antenna is superior in terms of safety and appearance.

FIG. 5a shows the antenna of FIG. 2a with a matching circuit added. Resonance is achieved between the coil 7 and the variable capacitance diode 8, and the impedance is matched by tapping down from the midpoint of the coil 7. The variable capacitance diode 8 applies a required DC voltage from a receiver in the vehicle through the coaxial cable 10.

In addition, 9 connects the balanced system of the antenna to coaxial cable 1.
This is a balun for converting to a zero unbalanced system.

FIG. 5b shows a configuration in which the matching circuit for the antenna shown in a is constructed using other matching means, in which the reactance is matched by the coil 7 and the variable capacitance diode 8, and the impedance is matched by the capacitor 11. The balun 9 and coaxial cable 10 are the same as in FIG. 5a.

FIG. 5c shows the antenna shown in FIG. 3 with a matching circuit added thereto, which is matched by a coil 7 and a variable capacitance diode 8, and connected to a coaxial cable 10.

FIG. 5d shows the matching means of the antenna matching circuit shown in FIG. 5c implemented using another matching method, in which the reactance is changed using the coil 7 and the variable capacitance diode 8, and the impedance is transformed using the capacitor 11 for matching. I try to let them do it.

FIG. 5e shows the antenna shown in FIG. 4 with a matching circuit added thereto, in which matching is achieved using a coil 7 and a variable capacitance diode 8.

FIGS. 5f and 5g show the matching circuit of the antenna of e in which matching is performed using another method, in which impedance transformation is performed using a capacitor 12, and matching is achieved using a coil 7 and a variable capacitance diode 8.

Generally, if the antenna is placed close to the vehicle body,
The radiation resistance of the antenna decreases, and the sensitivity decreases as it is, but by matching using the above method, the sensitivity improves. In addition, the variable capacitance diode 8 explained in the figure is one that applies a control voltage from the receiver controller in the car to achieve optimal matching.If the band is relatively narrow, the variable capacitance diode 8 is replaced with an ordinary capacitor ( It is also possible to place the capacitor in a fixed capacitor or semi-fixed capacitor.

FIG. 6 is a top view and a directivity diagram of a vehicle antenna according to an embodiment of the present invention attached to an automobile. In the figure,
Reference numerals 13 and 14 indicate antennas attached to the side visor, and 15 and 16 indicate antennas attached to the windshield, which may be any vehicle antenna such as a whip antenna. This sixth
By arranging multiple antennas at multiple locations as illustrated in the figure, antennas 13, 14, 15,
Each of the antennas 16 has unidirectionality as shown in the figure, and by switching these antennas to only the antenna in the direction of arrival of the radio wave, that is, the antenna that provides the maximum sensitivity, it receives only the direct desired wave and eliminates reflections. Since fewer waves are received, a stable level of radio waves can be received while driving, reducing fluttering and picket fencing. moreover,
By reducing the reception of reflected waves, ghosts and multipaths are significantly reduced.

Figure 7 shows a book that enables automatic FM diversity reception by installing multiple antennas on a vehicle as shown in Figure 6 and automatically switching antennas to reduce the various types of interference explained earlier. FIG. 1 is a configuration diagram of main parts of an embodiment of the invention. 13, 14, 15 in the diagram,
16 is an antenna with a matching circuit mounted on the vehicle as shown in FIG. 6, and these are connected to electronic or mechanical switches 17, 18, 19, and 20. Here, when receiving radio waves, at least one switch is on, and the radio waves enter the input terminal of the receiving circuit 22 via the DC blocking capacitor 21. 23 is a high frequency blocking coil, and the tuning voltage provided in the receiving circuit 22 is supplied from an output terminal 24 through the coil 23 to a matching circuit of each antenna.

26 is a multipath detection circuit. 27 is a reception input level detection circuit. A control circuit 28 collects signals from the multipath detection circuit 26 and the reception input level detection circuit 27, searches for and connects an antenna with the least multipath interference and level fluctuation. Note that the switches 17 to 20 have a configuration as shown in FIG. In the figure, 29 is a switch section, and 30 is a tuning coil for a tuning voltage path that supplies the matching circuit.

With the above configuration, the matching circuit of the side visor-mounted antenna is optimally controlled from the receiver side, and the most effective antenna against various types of interference is automatically selected, allowing for good diversity reception. becomes.

As is clear from the above explanation, the vehicle antenna of the present invention has unidirectionality and helps to effectively solve the various types of interference mentioned above, and its effects are very large. There is something.

[Brief explanation of the drawing]

Fig. 1 is an external view of an automobile showing an example of use of the present invention, Figs. 2 a, b, 3 and 4 are views for explaining each embodiment of the present invention, and Figs. 5 a, b. ，
c, d, e, f, and g are block diagrams showing more detailed embodiments of the present invention and examples of matching circuits that can be used in the present invention. A top view and a directivity diagram, FIG. 7 is a main part configuration diagram of an embodiment of automatic diversity reception of the present invention,
FIG. 8 is a detailed diagram of the switch section. 1, 1'...Side visor, 2, 2'...Conductor, 2a...Dipole antenna element, 4...Unipole antenna element, 5...Antenna conductor, 8
... Variable capacitance diode, 13-16 ... Antenna element, 100 ... Automobile.

Claims (1)

[Claims] 1 A plurality of antennas including an antenna attached to a side visor are provided at a plurality of locations, a matching circuit is provided in the antenna, a variable capacitance diode is connected to the matching circuit, and a variable capacitance diode is connected to a control section of the receiver. A vehicle antenna to which a control voltage is applied, wherein each of the plurality of antennas includes a receiving circuit, a multipath detection circuit, a level detection circuit, and a control circuit, and the switch is switched by the control circuit.