JPS63269625A - Antenna system for automobile - Google Patents

Abstract

PURPOSE:To contrive the improvement of the reception sensitivity from the VHF to the UHF band by using an output of an antenna having excellent reception sensitivity as a main output and applying the diversity reception while using the other antenna as the sub antenna. CONSTITUTION:In applying VHF reception, when the reception sensitivity of one antenna in two antennas 2, 3 tuned optimizingly to the VHF is excellent, the output of the antenna is extracted, and when the reception sensitivity is lowered depending on the direction of a radio wave, the UHF antennas 4, 5 near the antenna are selected as the sub antennas to cover the directivity and the outputs are synthesized with the outputs of the VHF antennas 2, 3. On the other hand, in the case of the UHF reception, when the UHF antennas 4, 5 whose reception sensitivity is deteriorated are used as the main antennas, the VHF antennas 2, 3 in the vicinity of the antennas are selected as the sub antennas and the outputs are synthesized. Thus, the diversity reception is applied so as to extract selectively the output of the antenna whose output is always at a high level and the reception sensitivity from the VHF to the UHF band is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an antenna device for an automobile that can perform diversity reception using an antenna arranged on a window glass of an automobile or the like.

(Prior art) When receiving FM radio broadcasts or television waves in a moving car, FM reception requires short cycles due to periodic fading that occurs due to fluctuations in the field strength of the received radio waves in the direction of travel. It may be difficult to recognize what is being received, such as when the received sound is interrupted, or when the TV is receiving VHF or UHF, the image disappears.

Conventionally, when receiving radio FM radio waves, the first and second antennas arranged on the window glass of a car are connected to a switch circuit, and the output of the antenna with better reception sensitivity is selected. A glass antenna for automobiles that enables directional diversity reception has been proposed (
(See Japanese Unexamined Patent Publication No. 196702/1983).

(Problem to be solved by the invention) However, in this type of antenna device, when an antenna with good reception sensitivity is used as the main antenna, two antenna patterns with different directivity are effectively used by supplementing with the other antenna. However, even when receiving FM radio waves, it is difficult to achieve omnidirectionality for incoming radio waves depending on the direction of travel of the vehicle, and deterioration in sound quality due to fluctuations in receiving sensitivity cannot be avoided. In addition, such an automotive antenna can be
Especially when used for receiving TV radio waves such as HF and UHF,
Radio waves with short wavelengths like UHF have properties similar to light rays in terms of their propagation, so car antennas almost always receive the waves directly, and when the car is running, they receive less energy than FM radio waves from a radio. Even if the directivity of each antenna becomes even higher, and one of the two antennas is used as the main antenna and the other as the sub-antenna, there remains the problem that the reception sensitivity will drop significantly depending on the direction of the incoming radio waves. It had been.

(Means for solving the problem) A means for solving the above problem is to convert two antennas of the antennas arranged on the window glass into VHF in a four-system diversity receiving glass antenna device. In addition to optimal tuning, the other two antennas are set to UHF.
The present invention relates to an antenna device for an automobile, characterized in that the four antennas tuned to the above are connected to a comparison switching unit that selects a UHF antenna as a sub-antenna when receiving VHF.

With the above configuration, when the main output is from an antenna with good receiving sensitivity, the present invention performs diversity reception using the other antenna as a sub-antenna, thereby achieving VH.
The aim is to improve reception sensitivity in the F to UHF bands.

(Function) When performing VHF reception, if the receiving sensitivity of one of the two antennas optimally tuned for VHF is good, the output of this antenna is extracted, but the receiving sensitivity may vary depending on the direction of the radio waves. When the antenna decreases, a UHF antenna near this antenna is selected as a sub-antenna to cover the directivity, and its output is combined with the output of the VHF antenna. On the other hand, when performing UHF reception, if a UHF antenna with reduced reception sensitivity is used as the main antenna, a VHF antenna near this antenna is selected as a sub-antenna, and its outputs are combined as described above. Therefore, diversity reception is performed such that the output of the antenna whose output is always at a high level is selectively extracted, so that reception sensitivity in the VHF to UHF band is improved.

(Example) Embodiments of the present invention will be described below based on the drawings.

<First Embodiment> An antenna device 1 for an automobile is shown in FIG.
and a second VHF antenna 2゜3, and a first and second
The main parts include UHF antennas 4 and 5, a comparison switching unit 6 to which the four antennas are connected, and are configured to perform diversity reception.

First VHF antenna 2 and second VHF antenna 3
has a length Q so that it can be tuned optimally to the VHF band.
The wavelength is approximately one-fourth the wavelength of VHF. 1st V
The HF antenna 2 is buried in a substantially horizontal direction below a left rear quarter window (hereinafter abbreviated as left rear window) 7, which is formed into a substantially trapezoidal shape and whose upper width is narrower than its lower width. Further, the second VHF antenna 3 is buried in a substantially horizontal direction below a right rear quarter window (hereinafter abbreviated as right rear window) 8, which has a substantially trapezoidal shape like the left rear window 7. and the first and second VH
The F antennas 2 and 3 are connected to the comparison switching unit 6 via a conductive wire 16 from a feeding point 9.9 provided at the rear side of the left and right windows 7.8.

First UHF antenna 4 and second UHF antenna 5
has length j2 so that it can be tuned to the UHF band.
2 is formed to be approximately one quarter of the wavelength of UHF, and is shorter than the first and second VHF antennas 2 and 3. The first UHF antenna 4 is installed on the left rear window 7.
It is buried above the first VHF antenna 2 in parallel with the first VHF antenna 2, and is arranged to match the shape of the left rear window 7.

Further, the second UHF antenna 5 is attached to the right rear window 8.
It is buried above the second VHF antenna 3 in parallel with the second VHF antenna 3, and is arranged to match the shape of the fabric rear window 8 like both the antennas 2 and 4. The first and second UHF antennas 4 and 5 are connected to the left and right windows 7.
．． The comparison and switching unit 6 is connected to the power supply points 9, 9 provided on the rear side of the power supply unit 8 via a conductive wire 16.

In this example, each antenna is described as a single antenna line, but it has a plurality of branch antennas buried in a substantially horizontal direction so as to deal with directivity in any direction. Needless to say.

The comparison switching unit 6 is equipped with a comparison circuit, a changeover switch, etc., and its output side is connected to a TV tuner 10 (not shown), and the comparison circuit compares the output of each antenna with a predetermined level value, and the changeover switch So-called diversity reception is performed by sending a selection signal to select an antenna with a good reception condition and switching a changeover switch.

Since the present embodiment is configured as described above, when performing VHF reception, the outputs of the antennas 2 to 5, which vary depending on the direction of travel of the automobile C, are compared with a predetermined standard level value in the comparator circuit. At this time, the first VHF antenna 2 and the first UHF antenna 4 are located almost at right angles to the incoming radio waves indicated by the arrow marks, and the receiving sensitivity is in a good state.
The comparison circuit detects that the output of the first VHF antenna 2 among the four antennas is at a high level.

As a result, when the selection signal is output from the comparator circuit to the changeover switch, the changeover switch operates to select the first VH.
The F antenna 2 is connected to the tuner 10, and its output is introduced into the tuner 10.

On the other hand, when the first VHF antenna 2 is located almost parallel to the incoming radio wave and the reception sensitivity drops below a predetermined level, a selection signal is output from the comparator circuit, the selector switch is operated, and the first UHF antenna 4 is connected to the tuner 6 as a sub-antenna. As a result, as shown in FIG. 4, the output of the main first VHF antenna 2 and the output of the sub first UHF antenna 4 are combined and introduced into the tuner 1o.

Next, when performing UHF reception, as shown in the case described above for VHF reception, the first UHF antenna 4 becomes the main antenna, and the first vHF antenna 2 becomes the sub-system, as shown in FIG. 4. The operation is performed and its output is introduced into the tuner 10.

Further, the second vHF antenna 3 and the second UHF antenna 5 of the right rear window 8 shown in FIG.
It is shown on the side A and operates in the same manner as described for side A above.

In this diversity reception, while the car C is running, the antenna closer to the incoming radio wave is selected preferentially, and even if the output of the main antenna decreases, the antenna near the main antenna is used as the sub antenna. Since the outputs of the main and sub antennas are combined and introduced into the tuner 10, a high level antenna output is always introduced into the tuner. Therefore, diversity reception is performed in which the output from the VHF band to the UHF band is in an optimal state.

<Second Embodiment> This example is shown in FIG.
This is an example in which four antennas are arranged. That is, the battery (
Rear window glass 1 that can be prevented from fogging by connecting a heater 13 between the busbars 12 and 12 connected to the rear window glass 1 (not shown)
A first VHF antenna 2 is arranged below the left side of 1,
A first UHF antenna 4 is arranged above. on the other hand,
A second VHF antenna 3 is provided below the right side R of the rear window glass 11, and a second UHF antenna 5 is provided above. The rest is the same as the first embodiment.

<Third Embodiment> This example is shown in FIG.
This is an example in which four antennas are arranged on the rear window glass 11. That is, the right side R above the front window glass 14
, the first VHF antenna 2 is installed, and the first UH antenna is installed on the left side.
An F antenna 4 is disposed, and a feeder line 15.15 is routed from above the center of the front window glass 14 to below. On the other hand, a second VHF antenna 3 is disposed on the right side R above the rear window glass 11, and a second UHF antenna 5 is disposed on the left side. The rest is the same as the first embodiment.

(Effects of the invention) Since the invention has the above configuration, when an antenna with good reception sensitivity is selected as the main antenna, diversity reception is performed using the other antenna as a sub antenna, so the output of the antenna that is always at a high level is Since it can be taken out, reception sensitivity can be improved and reception performance in the VHF band to the UHF band can be improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an antenna device for an automobile showing a first embodiment of the present invention, FIG. 2 is a front view of a rear window glass on which an antenna is arranged, showing a second embodiment of the present invention, and FIG. FIG. 4 is a perspective view of a car equipped with an antenna according to a third embodiment of the present invention, and FIG. 4 is a diagram illustrating a switching state when antennas are selected at the time of receiving the antenna. 1... Car antenna device, 2...
1st VHF antenna, 3...2nd VHF antenna, 4...1st UHF antenna, 5...
...Second UHF antenna, 6...Comparison switching unit, 10...Tuner, 11...
...Rear window glass, C...Car.

Claims (2)

[Claims] (1) In a 4-system diversity reception glass antenna device, two antennas are optimally tuned to VHF among the antennas arranged on the window glass, and the other two antennas are tuned to UHF. The four antennas are connected to a comparison switching unit that can select the UHF antenna as a sub-antenna when receiving VHF, and select the VHF antenna as the sub-antenna when receiving UHF. An antenna device for an automobile characterized by the following. (2) A UHF antenna is installed above one window glass, a VHF antenna is installed below, and a UHF antenna is installed above the other window glass, and a VHF antenna is installed below.
An antenna device for an automobile according to claim 1, wherein an antenna for a vehicle is provided.