JPH03250906A - Glass antenna for vehicle - Google Patents

Abstract

PURPOSE:To reduce the loss and to improve the transmission reception gain by arranging a 2nd antenna comprising horizontal elements whose length is 30-300mm from a 1st antenna to an outer ridge of a window pain and connecting the 1st antenna to an inner conductor of a coaxial cable and connecting the 2nd antenna to an outer conductor respectively. CONSTITUTION:A 1st antenna 3 comprising a vertical element 3a and a horizontal element 3b together with a heater wire 2 for frost resistance, a rectangular impedance adjustment antenna 4, a 2nd antenna 5 comprising horizontal elements together with a 1st feeding point 6 and a 2nd feeding point 7 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 8 of a coaxial cable 8, the 2nd antenna connects to an outer conductor 10 and the outer conductor connects to ground at a receiver side at the end.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial 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 1 Ball antennas have been put to 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 from the safety and appearance standpoint. 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 in view of the above points, and an object of the present invention is to provide a glass antenna for a vehicle for a car telephone or a 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, the linear antenna having a length of 30 mm.
A first antenna having at least a plurality of vertical elements of ~100 cm, an impedance adjustment antenna connected to the first antenna, and a length of 30 to 300 cm located on the outer edge of the window glass from the first antenna. The present invention is characterized in that a second antenna composed of horizontal elements is provided, and the first antenna is connected to an internal conducting wire of the coaxial cable, and the second antenna is connected to an external conducting wire of the coaxial cable.

[Function] Since car phones and personal radios transmit and receive vertically polarized waves, the vertical element becomes an effective component, and its length is determined by the resonance length λα/4 (λ is the wavelength of the radio wave and α is the wavelength shortening rate. Approximately 0.6) It is generally preferable to add a horizontal element to the front and rear ends of 30 to 100 irises, and the length of the horizontal element should be in the range of 15 to 40 irises. As shown in Examples 2 and 3, which will be described later, it may be better to add a vertical element to this horizontal element. However, although it is not possible to obtain high gain over a wide band with only one element, wide band performance can be obtained by providing multiple elements.

In addition, the impedance adjustment antenna matches the impedance of the coaxial cable, thereby improving the transmission and reception gain.

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 performs a matching function, in combination with the function of the impedance adjustment antenna, loss is reduced and transmission/reception gain is improved.

[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 6 show only the antenna portion of Embodiments 1 to 5 of the present invention, respectively. FIG.

This is an example in which single-pane glass is installed as the rear window glass of a vehicle. As shown in Figures 1 and 2, on the inside of the vehicle side of the glass plate 1 are vertical elements along with anti-fog heating strips 2. 3a
and a horizontal element 3b.
, a rectangular impedance adjustment antenna 4, and a second antenna 5 composed of a horizontal element, together with a first feeding point 6 and a second feeding point 7, are formed by screen printing and baking with a conductive paste. After that, it is attached to the rear opening of the vehicle, and the first
A second antenna is connected to the external conductor 10, and the external conductor is grounded on the receiver side at the end. The dimensions of each part of the vehicle glass antenna thus obtained are A.
, -1,180■, A2=1, 600 cranes, B1 fable 73
5 cranes, B2 fable 120■, B, -30 cranes, a=5m, b-
26m, c-25m, d = 15m, 6-5m, f
-10m5 g = 36m, h = 150, L-55
(2) When the transmitting and receiving gain in vertically polarized waves in the 860 MHz to 940 MHz car phone band was measured using a device with M=58 m and N=130 wr, the results shown in Table 1 were obtained.

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

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

In addition, at this time, the resistance R (Ω) and reactance X (Ω) (+: inductive, -: capacitive) between the feeding point of the first antenna and the feeding point of the second antenna are determined by the impedance adjustment antenna. Resistance R (Ω) when there is no (comparative example),
Wi the reactance X (Ω)! As a result, the results shown in Tables 2 and 3 were obtained.

Table 2 (Example) Table 3 (Comparative Example) As is clear from the results, the antenna of the present invention has a resistance R close to 50Ω and a dust actance X close to 0Ω compared to the comparative example. It can be seen that the impedance of the coaxial cable for feeding power to the bookmark, intransitive telephone, and personal radio is 50Ω, so the impedance is matched to that of the coaxial cable and efficient transmission and reception can be performed. It should be noted that the average gain of the comparative example is -7.5 dB in terms of dipole ratio, whereas the average gain of the present invention is -2.3 dB, which is a marked improvement.

In addition, when we measured the transmission and reception gain in vertically polarized waves of a personal radio with a center frequency of 904MHz, the dipole ratio was -0.5dB, which is because the transmission and reception gain of the ball antenna in practical use is almost equal to that of a half-wavelength dipole antenna. , it can be seen that the antenna is almost equivalent.

Furthermore, TV broadcast waves UH from 470MHz to 770MHz
When we measured the reception gain (dipole ratio) for F-band horizontally polarized waves and vertically polarized waves, they were -15, 3 dB, and -15, respectively.
It becomes 13.6 dB and can be received by this antenna.

2 to 5 Embodiment 2 shown in FIG. 3 has a vertical element 3c (b'-5Q■) added to the first antenna antenna 3, and a part (upper side) of the impedance adjustment antenna is made into an oven. Embodiment 3 shown in Figure 4 adds a vertical element 3c (b' = 50m) to one side of the first antenna 3,
A part of the impedance adjustment antenna (lower side) is left open, and the auxiliary antenna 11 (i=20 Tsuru, j
In the fourth embodiment shown in FIG. 5, the first antenna 3 is only the vertical element 3a,
A part (side) of the impedance adjustment antenna is opened, and an auxiliary antenna 12 (o=50 crane) is newly installed and connected to the first feeding point 6. Embodiment 5 shown in FIG. In this example, a new T-shaped element (L'-50■) is added to the first antenna, and a part of the impedance adjustment antenna (a part of the lower side) is made into an oven.The other configurations are as follows. Assume the same as Example 1.

With such a glass antenna for vehicles, 860M
When we measured the transmission and reception gain of the car phone band (Hz ~ 940M) and calculated the average value, the dipole ratio was -2.1 dB, -2.4 dB, -2.2 dB, respectively.
, -2.6 dB, and almost the same results as the glass antenna of Example 1 were obtained.

Also, 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 ratios were -0.5 dB and -0.8 dB, respectively.

-〇,6 dB -0,7 dB, which is the same as Example 1?
Results close to this were 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, a plurality of vertical elements having a length of 30 to 100 mm is an essential requirement, and a horizontal element and the vertical element 3c shown in Embodiment 2 and Embodiment 3 may be added. , and the distance from the heating filament is 1
It is better to have a distance of 51 or more.

As for the impedance adjustment antenna, in addition to rectangular and U-shaped antennas as shown in the embodiments, L-shaped antennas or a combination of these may also be used.

For the second antenna, the length N is between 30 and 300-1
Preferably, it should be 60 to 150 cranes, and the distance from the vehicle body should be 20 days or more, and the distance f from the first power feeding point is in the range of 5 to 30 cm, preferably 10 to 25 cm. You can select as appropriate.

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 depending on the vehicle model.

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 upper margin of the heating strip on the rear window glass, 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 are improved and the transmission/reception gain is also 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 6 show only the antenna portion of Embodiments 1 to 5 of the present invention, respectively. FIG. 1...3...4...5...8...9...10... Plate glass First antenna impedance adjustment antenna Second antenna Coaxial cable Internal conductor External conductor

Claims (1)

[Claims] In a glass antenna with a wire antenna provided on a vehicle window glass, the wire antenna has a length of 30 to 100 m.
a first antenna having at least a plurality of vertical elements of m, an impedance adjustment antenna connected to the first antenna, and a horizontal element with a length of 30 to 300 mm located closer to the outer edge of the window glass than the first antenna. A glass antenna for a vehicle, characterized in that the first antenna is connected to an internal conductor of a coaxial cable, and the second antenna is connected to an external conductor of a coaxial cable. .