JPH03250905A - Glass antenna for vehicle - Google Patents

Abstract

PURPOSE:To reduce the loss and to improve the transmission reception gain by connecting a 1st antenna shaped as a grating whose interval of grids is selected to be 1/16 of a wavelength lambda of a radio wave to be sent or received or below to an inner conductor of a coaxial cable and connecting a 2nd antenna comprising horizontal elements to an outer conductor. CONSTITUTION:A 1st antenna 3 formed to be a grating together with a heater wire 2 for frost resistance, a 2nd antenna 4 comprising horizontal elements together with a 1st feeding point 5 are formed onto the in-cabin side of a plate glass 1 by screen print and baking by means of conductive paste. Then the glass plate 1 is mounted to a rear opening of the car body, the 1st antenna connects to an inner conductor 7 of a coaxial cable 6, the 2nd antenna connects to an outer conductor 8 and the outer conductor connects to ground at a receiver side at the end. The lateral length M of the 1st antenna is selected to be 10-120mm and the longitudinal length L is selected within a range of 20-60mm and the most parts are formed to be a grating. The length N of the 2nd antenna is selected to be 30-300mm, preferably 60-150mm and the interval from the car body is to be 20mm or over.

Description

DETAILED DESCRIPTION OF THE INVENTION [Fields of Application] The present invention relates to a glass antenna provided on the window glass of a vehicle such as an automobile, and particularly to a glass antenna suitable for transmitting and receiving car telephones and personal radios.

[Prior Art] Conventionally, ball antennas have been put into practical use as vehicle antennas for transmitting and receiving car telephones and personal radios, but since they have a structure that protrudes from the vehicle body, they are not desirable in terms of safety and appearance. Not only does it not work, it also poses a problem when washing the car, and there is also a risk of breakage.

Therefore, in recent years, there has been a demand for glass antennas, and Japanese Patent Application Laid-open No. 62-69704, Japanese Utility Model Application No. 62-26912, etc. have been proposed.

However, both have considerably lower transmission and reception gains than ball antennas, so they have not yet been put into practical use.

[Object of the Invention] The present invention has been made with these points in mind, and it is an object of the present invention to provide a glass antenna for a vehicle for a car telephone or personal radio that can be put to practical use.

[Means for Solving the Problems] The present invention provides a glass antenna in which a linear antenna is provided on a vehicle window glass, in which the linear antenna has a horizontal length of 10 to 120 va and a vertical length of 20 to A first antenna, at least most of which is formed in a lattice shape, by horizontal elements and vertical elements each having a side length of 20 days or less, within a range of 60 cm; A second antenna consisting of horizontal elements with a diameter of 30 to 300 degrees is arranged, and the first antenna is connected to the internal conductor of the coaxial cable, and the second antenna is connected to the external conductor. It is characterized by

[Function] The present inventors believe that since car telephones and personal radios transmit and receive vertically polarized waves, a vertical element is an effective component, but it is not possible to obtain high gain over a wide band by itself. If the grid is combined with a horizontal element and the grid spacing is 1/16 or less of the wavelength λ of the radio waves to be transmitted and received, it is almost equivalent to a metal plate with the same area, so these are arranged in a specific range. The present invention was based on the discovery that broadband performance can be obtained by using the antenna as the first antenna.

In other words, as shown in the examples described later, the grid spacing is 5cm, which is 1716 or less of the wavelength λ of the radio waves to be transmitted and received, and the vertical length is λα/, which is the resonance length of the car phone or personal radio. 4 (α is the wavelength shortening rate of about 0.6), fixed at a value close to 40, and changing the lateral length M,
When the transmitting and receiving gains of a car telephone band from 860 MHz to 940 MHz were measured and the average value was calculated, the results shown in FIG. 6 were obtained.

As is clear from this result, the lateral length M is 10~
It can be seen that the number should be 120 squares, preferably 15 to 80 squares.

Further, when the length M in the horizontal direction was fixed at 20 cm and the length in the vertical direction was changed, the average value was measured in the same manner, and the results shown in FIG. 7 were obtained.

As is clear from this result, the length L in the vertical direction is 20~
It can be seen that the number should be 60 pieces, preferably 30 to 50 cranes.

Furthermore, the present invention provides a second antenna composed of a horizontal element and connects it to the external conductor of the coaxial cable, thereby making the glass antenna an ungrounded antenna and reducing the impedance with the unbalanced feed system (coaxial cable). Since it has a matching effect, it reduces loss and improves transmission and reception gain.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a front view showing Embodiment 1 in which the glass antenna of the present invention is provided on the rear window glass of an automobile, and FIGS. 2 to 5 show only the antenna portion of Embodiments 1 to 4 of the present invention, respectively. 6 and 7 are a characteristic diagram showing the relationship between the horizontal length M and the gain of the first antenna, and a characteristic diagram showing the relationship between the vertical length and the gain, respectively.

This is an example in which a single pane of glass is installed as a rear window glass of a vehicle, and as shown in FIG. 1, on the inside of the vehicle side of the pane glass 1, there is a first antenna 3 formed in a lattice shape along with anti-fog heating strips 2. , the second antenna 4 composed of horizontal elements, together with the first feeding point 5, is formed by screen printing and firing with a conductive paste. After that, it is attached to the rear opening of the vehicle, and the first
connect the second antenna to the external conductor 8,
The external conductor is grounded at the receiver end.

The dimensions of each part of the glass antenna for a vehicle obtained in this way are As-1,180 Tsuru, A2 = 1,600-, B
x-735m, B2=120tm, B3-
35mm, a-5m, b-7,5m, cs=5m, d-
5m, e-5kaku, f-15m, g-5wm, L
-40w, M=20cm, and N''140m, the transmitting and receiving gain in vertically polarized waves in the 860 MHz to 940 MHz car phone band was measured, and the results shown in Table 1 were obtained.

Note that the transmission and reception gain is expressed as a gain difference (hereinafter abbreviated as Goupole ratio) when the reception gain of a standard half-wavelength dipole antenna is set to OdB.

Table 1 As is clear from the results, the transmission and reception gain of the conventional ball antenna used in practical use is approximately equal to that of the half-wavelength dipole antenna, so it can be seen that it is a good antenna comparable to this antenna.

In addition, when we measured the transmission and reception gain in vertically polarized waves of a personal radio with a center frequency of 904M)Iz, the dipole ratio was +0.5 dB, which means that the transmission and reception gain of a ball antenna in practical use is almost equivalent to a half-wavelength dipole antenna. Since they are equal, it can be seen that the antennas are the same or slightly superior.

Furthermore, TV broadcast waves U from 470MHz to 770MFIz
When we measured the reception gain (dipole ratio) for horizontal and vertical polarization in the HF band, they were -15 and 1 dB, respectively.
-13.5clB, which can be received by this antenna.

2 to 4 Embodiment 2 shown in FIG.
Embodiment 3 shown in FIG. antenna 10
．． 10' was newly installed and connected to the first feeding point 5, and a second feeding point 11 was established by making the second antenna into a thin wire shape, and the dimensions of each part were o=10m, P=20mSM-20
In the fourth embodiment shown in FIG. 5, the size of the grid of the first antenna 3 is increased, and the feeding point 11 of the second antenna is provided at the top, and the dimensions of each part are increased. ax5m, b-156, c-20m, d-5m,
e=5m, f=15m, L-45m, M=4
5 mm, and the other configurations are the same as in Example 1.

With such a glass antenna for vehicles, 860M
) When the transmission and reception gain of the car phone band from Iz to 940MHz was measured and the average value was calculated, the dipole ratio was -1.9 dB, -1.6 dB, and -2.1 dB, respectively, which were the same as the glass antenna of Example 1. Almost the same results were obtained.

In addition, when we measured the transmitting and receiving gains in vertically polarized waves of a personal radio with a center frequency of 904 MHz, the dipole ratio was -0.5 dB and +0.1 dB-0, respectively.
, 9 dB, and a result equivalent to or close to that of Example 1 was obtained.

Although the present invention has been described above using preferred embodiments, the present invention is not limited to these embodiments, and various applications are possible.

For the first antenna, the lateral length M is 10-12
The length in the 0-1 vertical direction is within the range of 20-60fi, and the most part or the entire part may be in the form of a lattice, and the interval of the lattice (a in the example, b, c) are 4~
The distance from the heating filament should be 15 m or more.

For the second antenna, the length N is 30 to 300 cm,
Preferably, it should be 60 to 150 mm, and the distance from the vehicle body is preferably 20 mm or more, and the distance f from the first power feeding point is 5 to 30 m, preferably 10 to 25 mm, as appropriate. Just choose.

Although it is not necessary to provide an auxiliary antenna, it may be provided as necessary to improve the transmitting/receiving gain characteristics and directivity characteristics when a single type of antenna is insufficient.

In addition, in the embodiment, an example was explained in which the antenna was provided at the bottom of the heating strip, but if there is space above the heating strip, in other words, another glass antenna for receiving FM radio broadcast waves, TV broadcast waves, etc. If it is not provided, it may be provided in this area. In this case, it is preferable to have the antenna of the embodiment rotated 180 degrees for convenience of power supply. Furthermore, it is not limited to the rear window glass, but also the side window glass. , may be provided on the front windshield or sunroof.

Although the glass antenna of the present invention can be used alone,
The blank area above the heating stripes on the rear two windows, the front window glass,
It is more preferable to perform diversity reception with another glass antenna or a pole antenna provided on a side window glass, etc., since the directivity characteristics will be improved and the transmission/reception gain will also be improved.

[Effects of the Invention] The glass antenna of the present invention is particularly suitable as a transmitting/receiving antenna for car telephones and personal radios, and improves the gain to a practical level.

Furthermore, TV broadcast waves in the UHF band can also be favorably received.

[Brief explanation of drawings]

FIG. 1 is a front view showing Embodiment 1 in which the glass antenna of the present invention is provided on the rear window glass of an automobile, and FIGS. 2 to 5 show only the antenna portion of Embodiments 1 to 4 of the present invention, respectively. 6 and 7 are a characteristic diagram showing the relationship between the horizontal length M and the gain of the first antenna, and a characteristic diagram showing the relationship between the vertical length and the gain, respectively. 1 ... 3 ... 4 ... 6 ... 7 ... 8 ... Plate glass First antenna Second antenna Coaxial cable Internal conductor External conductor

Claims (1)

[Claims] In a glass antenna in which a linear antenna is provided on a vehicle window glass, the horizontal length of the linear antenna is 10 to 12.
0 mm, a vertical length within a range of 20 to 60 mm, and a first antenna whose at least most part is formed in a lattice shape by horizontal elements and vertical elements with a side length of 20 mm or less; A second antenna consisting of a horizontal element with a length of 30 to 300 mm is disposed closer to the outer edge, and the first antenna is connected to the inner conductor of the coaxial cable, and the second antenna is connected to the outer conductor of the coaxial cable. A glass antenna for a vehicle characterized by being connected.