JPH05218718A - Glass antenna for automotive use - Google Patents

Abstract

PURPOSE:To obtain a glass antenna for automotive use capable of using it as a sub-antenna receiving an FM radio broadcasting wave and a TV broadcasting wave with a high reception gain in every direction which ensures the operation as the antenna for key less entry such as open/close of a door and device control. CONSTITUTION:In the glass antenna receiving a radio wave whose frequency is f (MHz) and whose wavelength is lambda provided on the lower space of defrosting heater wires 2 of a vehicle rear window glass 1, 2-4 horizontal wires whose length is 0.02lambda.f<1/2>(1+ or -0.2) from a feeding point 4 provided on one side are disposed and an antenna 5 whose both ends are closed to constitute a loop element is at least provided on the glass antenna.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention receives transmission control information from a portable transmission section which wirelessly communicates control information necessary for controlling on-vehicle equipment such as opening / closing of a door or trunk room of an automobile or turning on / off a room lamp. It relates to a glass antenna for.

[0002]

2. Description of the Related Art In recent years, the frequency from a transmitter has been reduced to 5 in place of a door lock device using a general key.
A method of receiving a code signal by a weak radio wave of about 0 MHz, 250 MHz, and 300 MHz to open and close a door and control a vehicle device has received attention, and various proposals have been made.

As an antenna for a keyless entry for receiving such a signal by wireless communication, Japanese Patent Application Laid-Open No. 62-62
There is a type in which a pickup including a loop coil such as that shown in No. 37275 is built in a pillar or the like, but the influence of noise is great, countermeasures against it are necessary, and since it is embedded in the vehicle body, it is difficult to tune. There is.

On the other hand, a glass antenna in which a linear antenna is formed on the glass by screen printing is also disclosed in JP-A-63-434.
Although it has been proposed as No. 03, etc., the antenna provided on the lower side of the side window fluctuates in receiving gain due to opening and closing of the window, and as a result, it is difficult to operate especially when it is open, and The antenna provided has a stronger directivity than that provided on the front or rear window glass, and has the drawback that it may not operate depending on the direction of the oscillator.

The present invention has been made in view of the above points, and even in a narrow space of a lower margin of a heating wire,
The reception gain is high in all directions, and it is possible to perform operations such as opening and closing doors and controlling equipment with certainty.
An object of the present invention is to provide a glass antenna that can be used as a sub antenna for receiving M radio broadcast waves, TV broadcast waves, and the like.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a glass antenna for receiving a radio wave having a frequency of f (MHz) and a wavelength of λ, which is provided in the lower margin of the anti-fogging heating wire of a rear window glass for a vehicle. In Fig. 2, a horizontal strip with a length of 0.02λf ^1/2 (1 ± 0.2) from the feeding point provided on one side is
It is characterized in that at least four antennas are provided and the both ends are closed to form a loop.

[0007]

In general, the resonance length of a glass antenna is about (1/4) λα, where λ is the wavelength of the radio wave and α (about 0.7) is the wavelength shortening factor due to the glass, and is about 0.17λ. However, the present inventors have made the present invention based on the knowledge that the resonance length does not always become this length, and the resonance length changes depending on the frequency. The frequencies actually usable are 250 MHz and 300 Hz. In addition to the optimum length of 380 mm, 350 mm, 600 m at 100 MHz
From m, the optimum length is f ^1/2 when the frequency is approximately f.
It is found that the proportional constant should be 0.02λ, and therefore the optimum length should be 0.0 considering some width.
2λ · f ^1/2 (1 ± 0.2), that is 300MHz
(Λ = 1000 mm), 250 MHz (λ = 1200 m
m), 100 MHz (λ = 3000 mm), 50 MHz
350 for each (λ = 6000 mm) radio wave
± 70 mm, 380 ± 76 mm, 600 ± 120 mm,
850 ± 170 mm, and by arranging 2 to 4 horizontal filaments having a length in this range at upper and lower sides, and closing both ends to form a loop, the directional characteristics are improved,
It improves the reception gain in all directions.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. 1 to 6 show Examples 1 to 6 in which the glass antenna of the present invention is provided on a rear window glass for an automobile.
7 is a directional characteristic diagram of the antenna shown in Example 1 at 250 MHz, and FIG. 8 is a directional characteristic diagram of the antenna shown in Example 2 at 300 MHz.
In each case, the arrow indicates the traveling direction of the automobile.

Example 1 An example in which a single sheet glass is attached to a rear window glass of an automobile, and as shown in FIG. 1, the heating wire strips 2, 2, ... Together with the bus bars 3 and 3, the feeding point 4 and the antenna 5 forming a loop by closing both ends of the three horizontal filaments are screen-printed and baked with a conductive paste.

The dimensions of each part of the glass antenna for an automobile thus obtained are A ₁ = 1130 mm and A ₂ = 1.
330 mm, B = 710 mm, C = 380 mm, D ₁ =
When the reception gain of 250 MHz FM radio waves (horizontal polarization) from each direction was measured with D ₂ = 10 mm, E = 75 mm, and F = 10 mm, and the standard dipole antenna reception gain was set to 0 dB. When expressed by a gain difference (hereinafter, abbreviated as dipole ratio), it becomes as shown in the directional characteristic diagram of FIG. 7, and the reception gains every 5 ° (72 directions) are all higher than −20 dB, and in the 72 directions. -1 on average
Since it is 1.8 dB, and the reception gain required for operations such as opening and closing of doors and control of equipment is -25 dB, it can be operated well from all directions.

Example 2 In Example 2 shown in FIG. 2, the length C of three horizontal filaments is 350.
It has the same configuration and dimensions as the embodiment except that the auxiliary antenna 6 having a horizontal length of 100 mm and the auxiliary antenna 7 having a horizontal length of 290 mm are added.

With such a glass antenna for an automobile, the reception gain of an FM radio wave (horizontal polarization) of 300 MHz from each direction is measured and expressed as a dipole ratio.
As shown in the directional characteristic chart of FIG. 5, the reception gains every 5 ° (72 directions) are all above -20 dB, and the average value in 72 directions is -14.0 dB. Can be favorably operated from all directions.

Example 3 and Example 4 In Example 3 shown in FIG. 3, the antenna 5 has four horizontal filaments and D ₁ = D ₂ = D ₃ = 10 mm, and Example 4 shown in FIG. The tip of the antenna 5 of Example 3 on the center side is open, two sets of antennas 5 are arranged side by side, and an auxiliary antenna 8 is added. In each case, other configurations and dimensions are the same as those of Example 1. The same.

The reception gain of 250 MHz FM radio waves (horizontal polarized waves) from each direction was measured by such a glass antenna for an automobile, and when expressed as a dipole ratio, the antenna of Example 3 was averaged in 72 directions. The value is -12.4 dB,
The minimum value in 72 directions is −24.4 dB, the antenna of the fourth embodiment has an average in 72 directions of −12.9 dB, and the minimum value is −2.
The result is 1.5 dB, which is almost the same as that of the first embodiment, and the door and the like can be operated from all directions.

Example 5 Example 5 shown in FIG. 5 is one in which two horizontal filaments are provided as the antenna 5 and both ends are closed to form a loop, and D ₁ = 35 mm. Other configurations and dimensions are as follows. The same as in Example 1.

With such a glass antenna for an automobile, the reception gain of an FM radio wave (horizontal polarized wave) of 300 MHz from each direction was measured and expressed as a dipole ratio of 72.
The average value in one direction is -14.3 dB, and the minimum value in 72 directions is-
The value is 23.7 dB, which is almost the same as that of the second embodiment, and the operation of the door and the like can be performed from all directions.

This antenna can obtain the same result as that of the first embodiment even with respect to a radio wave of 250 MHz. Example 6 Example 6 shown in FIG. 6 has the same configuration and dimensions as Example 1 except that the antenna 5 has three horizontal filaments, the horizontal length C thereof is 840 mm, and the auxiliary antenna 9 is added. It is a thing.

With such a glass antenna for automobiles, the reception gain of an FM radio wave (horizontal polarization) of 50 MHz from each direction is measured and expressed as a dipole ratio. The average value in 72 directions is -14.3 dB. , -2 at the minimum value in 72 directions
It is 3.7 dB, and doors can be operated from all directions.

The preferred embodiment has been described above.
The invention is not limited to these, and various applications are possible.
It is possible. For antenna 5, the number of horizontal filaments is 2
~ 4, the length C is 0.02λ · f^1/2(1 ± 0.
It may be appropriately selected within the range of 2). Also, between horizontal lines
Distance D ₁, D₂, D₃Is 5 to 50 mm, preferably 10 to
You can choose it within the range of 30 mm, the top horizontal line and heating
It is better to make the line spacing F closer to the range of 5 to 15 mm.
Yes.

Elements such as 6, 7, 8 and 9 are not necessarily required as auxiliary antennas, but various auxiliary elements for the purpose of improving reception gain and directivity can be added.

Further, the glass antenna of the present invention is used alone as an antenna for keyless entry.
It can also be used as a sub-antenna for receiving M radio broadcast waves and TV broadcast waves. In this case, the glass antenna provided on the margin above the heating wire, the glass antenna provided on the front window glass, and the side When diversity reception is performed by using a glass antenna or a pole antenna provided on the window glass as a main antenna, more preferable results can be obtained as compared with the main antenna alone.

When laminated glass is used for the rear window glass, the glass antenna may be formed by embedding a metal thin wire such as a copper wire in an intermediate film such as polyvinyl butyral.

[0023]

EFFECT OF THE INVENTION The glass antenna of the present invention is formed by combining horizontal filaments of a specific length to form a loop.
Even if the antenna is provided in the narrow margin below the heating wire, it can be used particularly suitably as an antenna for keyless entry, and FM radio broadcasting wave, TV broadcasting wave V
It can also be used as a sub-antenna for receiving the HF band and the UHF band.

[Brief description of drawings]

FIG. 1 is a front view showing a first embodiment in which a glass antenna of the present invention is provided on a rear window glass for an automobile.

FIG. 2 is a front view showing a second embodiment in which the glass antenna of the present invention is provided on a rear window glass for an automobile.

FIG. 3 is a front view showing a third embodiment in which the glass antenna of the present invention is provided on a rear window glass for an automobile.

FIG. 4 is a front view showing a fourth embodiment in which the glass antenna of the present invention is provided on a rear window glass for an automobile.

FIG. 5 is a front view showing a fifth embodiment in which the glass antenna of the present invention is provided on a rear window glass for an automobile.

FIG. 6 is a front view showing a sixth embodiment in which the glass antenna of the present invention is provided on a rear window glass for an automobile.

FIG. 7 is a directional characteristic diagram of the antenna according to the first embodiment at 250 MHz.

FIG. 8 is a directional characteristic diagram of the antenna according to the second embodiment at 300 MHz.

[Explanation of symbols]

 1 Plate Glass 2 Anti-fogging Heating Wire 4 Feeding Point 5 Antenna 6, 7, 8, 9 Auxiliary Antenna

Claims (1)

[Claims] 1. A glass antenna for receiving a radio wave having a frequency of f (MHz) and a wavelength of λ, which is provided in a lower margin portion of an anti-fog heating wire of a rear window glass for a vehicle, and is provided at one side portion of the glass antenna. The length from the feeding point is 0.02λ · f ^1/2 (1 ±
A glass antenna for an automobile, comprising: 2 to 4 horizontal filaments of 0.2) and at least an antenna forming a loop by closing both ends.