JPS59196606A - U-shaped on-vehicle tv antenna - Google Patents

Abstract

PURPOSE:To obtain an antenna suitable for receiving a horizontally polarized TV broadcast wave by imbedding a U-shaped metallic plate in a window glass of a car. CONSTITUTION:The U-shaped metallic plate 1 is imbedded to a rear (or front) window glass 4 of the car and a coaxial cable 3 is connected to the middle part of the metallic plate. Then, the length (l) of the U-shaped metallic plate 1 is nearly a 1/2 wavelength of the TV broadcast wave or over, and much horizontal components exists in electric lines of force produced between the U-shaped conductor and a metallic car body 2 as shown in the arrow of figure. Thus, the U- shaped metallic plate is suitable for receiving a horizontally polarized TV broadcast wave.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an on-vehicle antenna for receiving VHF, UHF TV broadcasts in a vehicle.

In recent years, TV receivers have become more compact, making it easier to watch TV broadcasts in a car. Along with this, it has become necessary to have a receiving antenna suitable for use in vehicles.

Traditionally, portable TV receivers are equipped with a Rondo antenna, but in order to obtain sufficient reception sensitivity, one
It is necessary to extend the length up to 2 m, making it difficult to use in a narrow automobile and making it difficult to obtain good image quality. Moreover, some small TV receivers are equipped with an antenna terminal, and these TV receivers use an antenna that is attached to the front side of the vehicle body or on the side window. These antennas have a structure that protrudes from the car body, which is not only undesirable in terms of appearance, but also requires removal when washing the car, and can be easily tampered with when the car is parked and left. There were other problems, such as safety issues as people could get caught, and the paint on the car body could be scratched during installation, leading to rust on the car body. Additionally, since the car body is a good conductor, there is a problem in that good sensitivity cannot be obtained unless the sensor is placed at a sufficient distance from the car body.

The present invention eliminates the disadvantages of conventional antennas.The purpose of the present invention is to use the car window to effectively broadcast TV broadcasts without protruding to the outside of the car body or narrowing the space inside the car. The purpose is to perform reception inside a car. The present invention will be explained in detail below.

FIG. 1 shows an embodiment of the present invention, in which 1 is a U-shaped conductor, 2 is a metal car body, 8 is a coaxial feeder line, and 4 is a window glass. The U-shaped conductor 1 is provided along the upper and lower horizontal sides and the right vertical side of the window at an appropriate distance from the vehicle body. Both ends are grounded to the vehicle body. (It may not be grounded.)
"-The total length l of the U-shape between the grounding end of the side and the grounding end of the bottom side is approximately 1/2 wavelength of the lowest frequency used or longer."
It is desirable that it be Yu. Connect the center conductor of the coaxial feeder line to the U-shaped conductor, and the outer conductor to the vehicle body near the center of the right side.
Then, it is excited as an antenna. The antenna and the vehicle body may be coupled by capacitive coupling. Figure 2 is an elevational view of the U-shaped conductor attached to the rear window, and arrows indicate the lines of electric force 5 that occur between the U-shaped conductor and the vehicle body. . According to the figure, the electric lines of force generated between the U-shaped conductor on the right side and the vehicle body have a horizontal component, and it has the function of receiving horizontally polarized TV radio waves that are normally broadcast. are doing. Other parts work as loading.

Figure 3 shows an example of actually measured horizontally polarized radiation directivity of this antenna. It has great sensitivity in the longitudinal direction of the vehicle body. Fourth
Figure 1 shows an example of actual VSWR measurement.

Normally, there is a daylight camera baked into the window glass in the rear car window, but as shown in Figure 5(a), the U-shaped antenna element is placed almost around daylight daylight 6 (a little apart from daylight daylight)... For example, if the antenna is placed on the opposite side of the window glass from where the diffuser burns, the main part of the electric field will be generated between the U-shaped conductor and the vehicle body, so the antenna will maintain normal operation.

The width W (see FIG. 1) of the U-shaped conductor is related to radiation impedance, so it is best to select an appropriate value. As a practical structure, one in which several thin wires 7-1 are arranged in parallel as shown in FIG. 6 can be considered.

This is made by arranging and fixing ultrafine wires on a U-shaped transparent plastic plate 7-2, and this plastic plate is attached and placed around the window.

Since the radiating element used as an antenna is an ultra-fine wire, the plastic plate acts both as a strength-retaining material and as an insulating spacer between the diffuser conductor printed on the window glass. If an antenna element having such a structure in which ultrafine wires are fixed to a transparent plastic plate is used, it is advantageous because it is hardly noticeable in appearance.

FIG. 5(b) shows that the shape of the day camera 6 has been changed,
This is a practical example of a U-shaped conductor printed on a glass plate.

As seen in Figure 4, the input impedance of this antenna changes depending on the frequency. Therefore, an actance compensation matching circuit as shown in FIG. 7 is inserted between the coaxial feeder line and the antenna element at the antenna excitation point to improve sensitivity.

Figure a) shows that when a diode is connected in parallel to the compensation coil and used at low frequencies (Low channel region), all L of the coil is connected in series with the antenna element, and when used at high frequencies (Hfgh Channel region). When used, current is passed through the diode in the forward direction to short-circuit the coil, and the antenna and feed line are directly connected.

This increases the low channel sensitivity by 10 dB.
I can be more senior than you.

Figure 7 1)) is possible by connecting a capacitor in series with the coil and short-circuiting them with a diode.
The optimum beam actance is inserted in series with the low channel, high channel, or UHF band and the frequency band, and the antenna beam actance is canceled out so that the highest sensitivity can always be obtained.

In FIG. 7C), series C is used as a varactor, and C is adjusted by the applied voltage of k.

As mentioned above, various measures can be taken to impedance matching between the antenna and the coaxial feed line, but as the frequency range becomes wider, it is unavoidable that reactance components remain in the antenna.

For this reason, it is effective for the reception C/H to insert an appropriate amplification circuit directly after the compensation circuit at the feed point and operate it as an active antenna, as shown in FIG. Figure a) is
As an active circuit, a common emitter type transistor amplifier b) is a common-emitter type C) is a source follower type F
It is an ET amplifier. These can be used depending on the dimensions of the structural antenna element of the vehicle body.

In the explanation so far, the U-shaped conductor is arranged along the upper and lower sides and the right vertical side of the car window, but there is no problem in placing it along the left vertical side.

Also, if U-shaped conductors are provided on both the left and right sides as shown in Figure 9, and both are excited in opposite phases using the phase shifter 8 and combiner 9, the longitudinal axis of the vehicle body as shown in Figure 10 can be created. A symmetrical composite directivity is obtained with respect to

As described above, according to the present invention, it is possible to satisfactorily receive TV broadcasts inside a car without extending the antenna conductor from the car body or narrowing the space inside the car. be.

[Brief explanation of the drawing]

1, 2, 5(a) and 9, and 9 show embodiments of the present invention, in which a U-shaped in-vehicle TV antenna is attached to the window of an automobile. Figure 3 shows the horizontal polarization directivity when one set of antennas of the present invention is installed, and @IO diagram shows the horizontal polarization directivity when two sets are installed (a) (b) (c) Beam actance compensation An example of the circuit is shown in Fig. 8(a)(b) (
C) shows an example of an increase [1] circuit. In the figure, 1 is a U-shaped conductor, 2 is a metal car body, 3 is a coaxial power supply line, 4 is a window glass, 5 is an electric line of force, 6 is a diffogger,
7-1 is a conductor thin wire, 7-2 is a plastic plate, 8 is a phase shifter, and 9 is a synthesizer. 3 Shuminfang 20 Yoshi 4 figure (.) T field (b) W8 figure

Claims (5)

[Claims] (1) A conductor placed along the window glass or enclosed within the window glass with an appropriate gap from the window frame along the top and bottom horizontal sides and either the left or right vertical sides of the front or rear window frame of the vehicle. A U-shaped in-vehicle TV antenna characterized by using a plate or a group of thin conductor wires as the antenna. (2) The U-shaped in-vehicle TV set forth in claim (1), wherein the conductor thin wire group is arranged and fixed on a plastic flat plate, and the plastic flat plate is arranged along a window glass. antenna. (3) Install it along the lower horizontal side of the front or rear window frame of the vehicle and along either the left or right vertical side with an appropriate gap between the window frame and the window frame, or by enclosing it inside the window glass. A U-shaped in-vehicle TV antenna, characterized in that the antenna is a conductor plate or a group of thin conductor wires, and a reactance compensation circuit is connected to the antenna. (4) The window frame at the front or rear of the vehicle should be placed along the window glass or enclosed within the window glass with an appropriate gap from the window frame along the lower horizontal side and either the left or right vertical side. 1. A U-shaped in-vehicle TV antenna, characterized in that a conductor plate or a group of thin conductor wires is used as an antenna, and a reactance compensation circuit and an amplifier circuit are connected to the antenna to operate as an active antenna. (5)! J 7 A reactance compensation circuit is composed of a circuit including one or more inductances, capacitances, and diodes, and at relatively low frequencies, at least one of the diodes is not made conductive and the entire reactance compensation circuit is inductive, and compared. Claims (3) or (4) characterized in that at least one or more of the diodes is made conductive at high frequencies to cause the reactance compensation circuit as a whole to operate as a receptive or slightly inductive circuit.
) U-shaped in-vehicle TV antenna described in item 2.