JPH0119764B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a glass antenna for a vehicle, and more particularly to a glass antenna for a vehicle suitable for receiving radio waves provided on a window glass of an automobile.

In recent years, so-called anti-fog glass antennas that are equipped with heating stripes and antenna stripes have begun to be used in the rear window glass of automobiles.

However, when such an anti-fog glass antenna receives FM broadcast radio waves, the reception gain is minimum for radio waves arriving from the front and rear of the car, and the reception gain is maximum for radio waves arriving from the side of the car. Therefore, the gain difference was large, and high gain could not be obtained over the entire frequency band.

Moreover, the difference in gain is large. Therefore, conventional anti-fog glass antennas have strong directional characteristics, and when receiving FM broadcast radio waves in a place with weak electric field strength, the gain decreases depending on the direction of the vehicle or the frequency. The drawback was that it became difficult to receive broadcasts.

The present invention eliminates such drawbacks and improves not only the directivity characteristics but also the average gain over the entire frequency range of FM broadcast radio waves, and is also suitable for receiving FM broadcasts (vertical polarization) in the United States, Europe, etc. The purpose of the present invention is to provide a suitable glass antenna for vehicles, which includes a heating wire/receiving antenna installed in the heated area of the window glass of a vehicle, especially an automobile, and a receiving antenna installed above the heating line outside the heated area. The antenna has a horizontal part and a vertical part, and the vertical part has a T-shaped main antenna connected to the heating filament and receiving antenna, and an auxiliary antenna consisting of at least one horizontal filament connected to one side of the vertical part. This is accomplished by providing a partially open or completely closed impedance adjustment antenna connected to the other side of the vertical portion via a horizontal line, and providing a feeding point to the impedance matching antenna.

The present invention will be explained below based on the drawings.

FIG. 1 shows a glass antenna showing a first embodiment of the present invention, and is an antenna pattern particularly suitable for receiving domestic FM broadcasting (horizontally polarized waves). 1 is a glass plate forming the rear window of a car, for example. , 2 is a heating filament and receiving antenna (hereinafter referred to as heating filament);
3 is a T-shaped main antenna having a horizontal portion 4 and a vertical portion 5, 6 is an auxiliary antenna, 7 is an impedance matching antenna, and 8 is a feeding point.

Fig. 2 shows a glass antenna showing a second embodiment of the present invention, Fig. 3 shows a glass antenna showing a third embodiment of the invention, and Fig. 4 shows a glass antenna showing a fourth embodiment of the invention. The equivalent of FIG. 1 (first embodiment) is shown.

When the vehicle glass antenna of the present invention receives FM broadcast waves, the T-shaped antenna acts as the main antenna over the entire FM frequency range, the heating wire acts as a receiving antenna, and the auxiliary antenna acts as a receiving antenna for waves reflected by the vehicle body, etc. Since it has the effect of reducing the influence, the antenna gain is improved and the directivity characteristics are improved.Also, by providing an impedance matching antenna, the impedance of the antenna and the receiver are approximated, increasing reception sensitivity, and the impedance matching antenna. By adjusting the appropriate connection position (tap) and the length of the main antenna, it is possible to improve the antenna gain and frequency characteristics.

In a vehicle glass antenna with such a configuration, the glass dimensions shown in Fig. 1 are A = 1100 mm,
A′=1450mm, B=590mm, and the dimensions of each part of the antenna wire are M=510mm, L=520mm, l=160mm,
d=10mm, e=60mm, f=30mm, x=320mm, y
=500mm, p=15mm, q=15mm, c=30mm, g=
30 mm, j = 10 mm, k = 20 mm, h = 40 mm, and the FM band directivity characteristics of the antenna were measured using the heating wire 2 with 13 wires arranged at an interval of 35 mm. Characteristics as shown in Figs. 1, 6, and 7 were obtained. Figure 5 is 80MHz, Figure 6 is 83M
Hz, Figure 7 shows the directional characteristics of horizontally polarized FM band at 86 MHz (the dotted line shows the directional characteristics of a whip antenna with a length of 1 m).

As is clear from FIGS. 5, 6, and 7, the glass antenna of this embodiment can provide extremely good omnidirectionality for radio waves arriving from any direction. In addition, the reception gain of this example is the fifth
It can be seen that the gains are similar and high when compared with the whip antennas shown in Figures 6 and 7, but the average gain in the horizontally polarized FM band is the gain of a 1m long rear whip antenna. The gain difference when 0dB is -5.5dB at 80MHz, -4.7dB at 83MHz, -7.4dB at 86MHz, and an average of -5.8dB, which means that the average gain of a conventional good glass antenna is about -8dB. Therefore, it can be seen that it is extremely high.

In addition, in the antenna pattern of the first embodiment, when there is no auxiliary antenna and when there is only a conductive wire instead of the impedance matching antenna, one end of which is connected to the vertical part and power is fed to the other end, the horizontally polarized FM band When we actually measured the average gain of
0.4 dB, -2.7 dB at 83 MHz, -1.2 dB at 86 MHz, and -1.2 dB on average.
-14.2dB at 15.3MHz, 83MHz, - at 86MHz
10.6dB, average -13.3dB, and it can be seen that the auxiliary antenna and the impedance matching antenna, especially the impedance matching antenna, greatly contribute to the gain improvement.

In particular, since it sufficiently compensates for the drop in gain of the whip antenna, it is very effective as a glass antenna in a so-called diversity receiving antenna, which uses both a whip antenna and a glass antenna and switches to the antenna with the best reception condition each time.

Next, the glass antenna shown in FIG. 2, which shows the second embodiment of the present invention, is similar to the antenna of the first embodiment except that the stub of the impedance matching antenna is open, and the dimensions are almost the same. The average gain in the FM band was actually measured, and the gain difference when the gain of a 1m long rear whip antenna was 0dB was -7.0dB at 80MHz, 83M
-4.2dB at Hz, -3.8dB at 86MHz,
It can be seen that the average value is -5.6 dB, showing similar characteristics.

Next, the glass antenna shown in FIG. 3, which shows the third embodiment of the present invention, is the antenna of the first embodiment with two auxiliary antennas, and the dimensions of each part are A =
1100mm, A′=1450mm, B=590mm, M=520mm,
L=530mm, L′=510mm, d′=30mm, e′=30mm, f
=30mm, x=320mm, y=500mm, p=15mm, q=
15mm, c=30mm, g=30mm, j=10mm, k=20
mm, h = 40 mm, and the heating wires were arranged under the same conditions as in the first embodiment.The average gain of the horizontally polarized FM band was actually measured, and the gain of a 1 m long rear whip antenna was calculated. Indicated by the gain difference when set to 0dB,
-7.5dB at 80MHz, -7.5dB at 83MHz
It can be seen that at 5.5 dB and 86 MHz, it is -8.2 dB, and the average is -7.1 dB, showing almost the same characteristics.

Next, the glass antenna shown in FIG. 4 showing the fourth embodiment of the present invention is particularly suitable for receiving FM broadcasting (vertical polarization) in the United States and Europe, and the dimensions of each part are A=1100, A' =1450mm, B=590mm, M=
300mm, L=415mm, e=60mm, f=30mm, x=
320mm, y=500mm, p=15mm, q=15mm, c=30
mm, g = 30 mm, j = 10 mm, k = 20 mm, h = 40 mm, and 13 wires are arranged at a spacing of 35 mm as heating wire 2.
When we measured the average gain in the FM band, the gain difference was -18.9dB at 90MHz, when the gain of a 1m long rear whip antenna was 0dB, which was -18.9dB at 100M.
-15.8dB at Hz, -7.9dB at 108MHz,
The average gain is -14.2 dB, which is extremely high since the average gain of a conventional good glass antenna is about -20 dB.

The antenna of the fourth embodiment has a reception frequency of 90MHz~
Since the frequency is as high as 108 MHz, compared to the antenna of the first embodiment, the horizontal length of the main antenna is shortened, and the auxiliary antenna is configured with only a relatively short horizontal portion without folding back its ends. It has almost the same configuration as the antenna of the first embodiment, and the gain of the antenna of the first embodiment was calculated by actually measuring the average gain in the vertically polarized FM band.
Assuming 0dB, the gain difference is -5.8dB at 90MHz, +19.3dB at 100MHz, +3.9dB at 108MHz, and +5.8dB on average, resulting in vertical polarization.
It is clear that this antenna is suitable for receiving FM radio waves.

In the above example, the effects of this example were explained by specifying the dimensions of each part of the antenna wire and actually measuring the characteristics of the antenna. However, the optimum dimensions of each part of the antenna wire can vary depending on the type of car (opening, glass installation angle, feeder length, wiring location, etc.).
When receiving horizontally polarized FM waves between 76MHz and 90MHz, the length M of the horizontal part that mainly operates as the main antenna is (λ/4)a±(λ/20) where the wavelength of the FM broadcast frequency is λ. ) a (a is the wavelength shortening rate of the glass antenna, approximately 0.7), that is, 450
~850mm, the length L for phase adjustment is the same as M (λ/4)a±(λ/20)a, that is, in the range of 450~850mm, and the length y of the impedance matching antenna is (λ /8)a-(λ/20)
a) ~ (λ/4) a + (λ/20) a) i.e. 200
~850 mm, the capacitance is increased for the length l of the folded part, and the impedance has an effect over a wide band with less change, but L
When is the resonance length, Q (= 1/ωCR) will be high and the gain will be high, so in this case it is better not to fold back, but in other cases it is better to fold back, 300
mm or less, the length x of the connection point of the impedance matching antenna is in the range o to y (x = y in the case of Fig. 12 described later), and other d,
For the lengths of e, f, p, q, c, g, j, k, and h, select the optimal value for each within a range of at least 3 mm to reduce stray capacitance with other parallel elements. Bye.

Although the present invention has been described above using four embodiments, the antenna of the present invention is not limited to these, and the following modifications are also possible.

(1) The T-type main antenna wire is shown in Figures 8, 9, and 1.
As shown in FIG. 0, the horizontal portion may be composed of two or more filaments (FIG. 8), or the ends thereof may be folded back (FIG. 9). Further, the vertical portion may also be configured to have two filaments instead of one so that the T-shape forms a loop (FIG. 10).

(2) The number of horizontal lines on the auxiliary antenna is 1 in Figure 1.
It is not limited to books; it may be larger than that as shown in FIG. 3, and exhibits almost the same characteristics.

(3) The impedance matching antenna is shown in Figure 11.
As shown in FIG. 12, there are not only stub-shaped ones as in the embodiment, but also FIGS. 13, 14,
It may also be shaped as shown in FIG. It should be noted that what is most effective in matching the impedance here seems to be things other than conductive wires, such as stub-shaped ones or 〓-shaped ones in Figure 13, but the conductive wires connected to these Since the strips do not have any effect on impedance matching, they are treated as part of the impedance matching antenna in this specification.

Further, in the embodiments of the present invention, the glass antenna is printed and baked with a conductive paste, but it goes without saying that it may also be formed by embedding thin metal wires in the laminated window glass.

As described above, the glass antenna of the present invention has improved directional characteristics over the entire FM frequency band compared to conventional glass antennas, and the average gain is significantly improved, as well as the average gain in the vertically polarized FM frequency band. This has the great effect of increasing the gain.

[Brief explanation of drawings]

1, 2, 3, and 4 are plan views of a glass antenna showing one embodiment of the present invention, and FIG.
Figures 6 and 7 are directional characteristic diagrams at 80MHz, 83MHz, and 86MHz, respectively, of the glass antenna in Figure 1 (first embodiment) (the dotted line is a 1m long rear whip antenna), Figures 8 and 9. 10 show modified examples of the main antenna of the present invention, and FIGS. 11, 12, 13, 14, and 15 show modified examples of the impedance matching antenna of the present invention. DESCRIPTION OF SYMBOLS 1... Plate glass, 2... Heating wire/receiving antenna, 3... Main antenna, 4... Horizontal part, 5... Vertical part, 6... Auxiliary antenna, 7... Impedance matching antenna, 8... Feeding point.

Claims (1)

[Claims] 1. In a glass antenna for a vehicle that has a heating filament/receiving antenna installed in the heated area of the plate glass and an antenna installed above the heating line outside the heated area, the antenna installed outside the heated area is
a T-shaped main antenna having a horizontal part and a vertical part, the vertical part being connected to the heating wire and receiving antenna;
An auxiliary antenna consisting of at least one horizontal filament connected to one side of the vertical part of the main antenna line, and a part connected via a horizontal filament to the other side of the vertical part of the main antenna line is open. Alternatively, a glass antenna for a vehicle is provided with a completely closed rectangular impedance matching antenna, and the impedance matching antenna is provided with a lead-out point to a feeding point.