JPH0516681B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a windowpane antenna for automobiles, and is particularly suitable for use in receiving VT broadcast waves in the VHF or UHF band.

[Conventional technology]

2. Description of the Related Art Conventionally, it is known that an antenna wire for receiving radio broadcast waves is attached to the inner surface of a rear window glass of an automobile along with a heater wire for preventing fogging. These antenna wires are generally tuned to obtain good reception output in the AM and FM bands, and in order to receive TV broadcast waves.
Requires a separate dedicated antenna tuned for TV.

However, TV broadcast frequencies are limited to low bands (first to
3rd channel 90~180MHz) to high band (4th channel ~ 12th channel 170~222M)
Hz), requiring very wideband antennas. Window glass antennas currently in practical use have a relatively narrow FM band (70 to 90M).
Hz), but the reality is that no matter how much tuning you do, you cannot obtain satisfactory performance for the entire TV broadcast band. Moreover, the area of the rear window glass is limited, and the position and area of the antenna wire are often restricted in order to attach a heater wire or to ensure rearward visibility. Therefore, the shape of the antenna is limited, and it is difficult to attach a high-sensitivity, broadband antenna wire with a large number of elements to a window glass.

[Problem that the invention seeks to solve]

In view of the above-mentioned problems, an object of the present invention is to provide a window glass antenna for an automobile, which has excellent characteristics of high sensitivity and wide band, and can also receive VHF and UHF TV broadcast waves.

[Means for solving problems]

The automobile window glass antenna of the present invention is provided by dividing a pair of substantially similar antenna element groups 2a and 2b constituting one balanced feeding type antenna wire into two parallel planes formed by the window glass. It is characterized by this. With this configuration, the area of the window glass can be doubled and a high-sensitivity, broadband antenna wire can be attached.

〔Example〕

FIG. 1 is a diagram showing an antenna pattern on the rear window glass surface of an automobile, showing an embodiment of the window glass antenna of the present invention. In this embodiment, antenna elements are attached to the front surface 1a and back surface 1b of the rear window glass 1 by silver paste printing or the like. Antenna element group 2a on the front side and antenna element group 2b on the back side
The pair constitutes one parallel-fed antenna,
A pair of power feeding points 3a, 3 provided on the front and back surfaces
Receives balanced power from b. That is, a balanced feeding type antenna consisting of a pair of symmetrical or substantially similar antenna element groups is folded into two and arranged on the front surface 1a and the back surface 1b of the rear window glass 1.

The antenna pattern shown in FIG. 1 is a log-periodic antenna, in which each vertical element a,
The length and spacing of b have been varied. The antenna element groups 2a and 2b on the front surface 1a and the back surface are each symmetrical with respect to the center line of the rear window glass 1, and the element lengths are gradually shortened from the center toward both sides. Note that the longest element a is located at the center of the surface 1a.
, the second element b is on the back surface 1b
Then, the third element is again placed on the surface 1a, and so on. That is, the antenna element groups 2a and 2b have substantially similar shapes on the front surface 1a and the back surface 1b. If the length of the element exceeds the width of the rear window glass 1, the tips of the vertical elements a and b can be bent at right angles to extend them to both sides in the horizontal direction, as shown in FIG.

The received output derived from each feeding point 3a, 3b in FIG. 1 is converted into an unbalanced output by a balun 3 as shown in FIG.
Derived from TV Chuyuna. Note that the output may be directly led to the tuner using a parallel feeder line without converting to an unbalanced output.

Fig. 3 is a frequency characteristic diagram of the VHF band of the window glass shown in Fig. 1, and Fig. 4 is a frequency characteristic diagram of the FM band. As shown in FIGS. 3 and 4, very high sensitivity and wideband reception characteristics can be obtained. Although not shown in FIG. 3, the receivable frequencies extend to the UHF band, and it is also possible to receive TV broadcasts in the UHF band.

5 and 6 show a method of arranging antenna elements when the weather resistance of the antenna element 3a on the front side of the window glass 1 is a problem. Figures 5 and 6
In the illustrated example, a laminated glass is used in which two glass plates 6 and 7 are bonded together via an adhesive intermediate layer 8 such as polyvinylbratyl. Antenna element group 2
In FIG. 5, a and 2b are provided on the front surface 6a and the back surface 6b of the glass plate 6 on the inside of the vehicle. Further, in FIG. 6, an antenna element group 2b is attached to the front surface 6b of the glass plate 6 on the inside of the vehicle, and an antenna element group 2a is attached to the back surface 7b of the glass plate 7 on the outside of the vehicle.
Each element group 2a, 2b is insulated by an adhesive intermediate layer 8. According to the configurations shown in FIGS. 5 and 6, the antenna element 2a is not exposed to the outside of the vehicle, so there is no problem with weather resistance.

7 and 8 show modified examples of the antenna pattern. FIG. 7 shows an arrangement in which almost completely symmetrical logarithmically periodic antenna element groups 2a and 2b are divided into a front surface 1a and a back surface 1b. Also, Fig. 8 shows a log-periodic antenna almost similar to Fig. 7, but
In this example, the elements are arranged alternately on the front surface 1a and the back surface 1b in order of length. Therefore, each antenna element group 2
a and 2b are not symmetrical but similar.

In the above embodiment, the antenna element groups 2a and 2b are attached to the front and back surfaces of the rear window glass 1, but if there is a fixed fitted window glass (rear window glass) on the side of the vehicle that cannot be opened freely, , antenna elements may be arranged on the front and back surfaces of the antenna to receive balanced power feeding.

〔Effect of the invention〕

As described above, in the present invention, the pair of antenna elements constituting the balanced feeding type antenna wire is divided into two parallel planes formed by the window glass, so the area of the window glass is doubled. Even when the area of the window glass is small compared to the area occupied by the antenna, or when the antenna installation position on the window glass surface is limited, it is possible to attach a high-sensitivity, broadband antenna line with a large number of elements. becomes possible.

[Brief explanation of the drawing]

Fig. 1 is a pattern diagram of an automobile rear window glass antenna showing an embodiment of the present invention, Fig. 2 is an output circuit diagram of the antenna of Fig. 1, and Figs. 3 and 4 are diagrams of the antenna of Fig. 1. Frequency characteristic diagrams for VHF band and FM band, Figures 5 and 6 are cross-sectional views of glass when an antenna element is attached to laminated glass, and Figures 7 and 8 are first diagrams showing modified examples of antenna patterns.
It is a pattern diagram of the rear window glass surface similar to the figure. In addition, in the codes used in the drawings, 1...Rear window glass, 1a...Front surface, 1b...Back surface, 2
a, 2b... antenna element group, 3... balun, 4
...Coaxial feeder wire, 6,7...Plate glass, 8...
...an adhesive intermediate layer.

Claims (1)

[Scope of Claims] 1. An automobile characterized in that a pair of antenna elements of substantially similar shape constituting one balanced feeding type antenna strip is divided into two parallel planes formed by window glass. Window glass antenna. 2. The automobile window glass antenna according to claim 1, wherein the antenna wire has a logarithmically periodic antenna pattern.