JPS59210703A - Glass antenna for vehicle - Google Patents

Abstract

PURPOSE:To improve the mean gain and directivity to FM broadcast radio wave in Japan, and Europe and America by providing a T type antenna and two antennas which extend horizontally at both sides of the vertical part of the former antenna, and providing one of the antennas and giving both antennas left-right asymmetry. CONSTITUTION:Heating wire streaks 2 are provided on plate glass 1, and the 1st T type antenna consisting of a horizontal part 5 and folded parts 6b and 7b is provided above them. Elements 6 and 7 are the 2nd and the 3rd antennas which have horizontal parts 6a and 7a, and folded parts 6b and 7b, and provided to the vertical part 7c where a lead-out point 9 to a feeding point 8 is connected to the horizontal part 7a and folded part 7b of the 3rd antenna 7, and the lead-out point 9 is connected to the feeding point 8 by a conductor 10. The 1st antenna operates as a main antenna over the entire FM frequency range in said constitution, and the 2nd antenna eliminates the phase difference between a direct and a reflected wave to improve the directivity and mean gain. In addition, the 3rd antenna approximates the impedance of the antennas and that of a feeder to each other to improve the reception sensitivity.

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, automobile window glasses equipped with heating stripes and antenna stripes have begun to be used. There are two types of these so-called anti-fog glass antennas.

The first type is one in which a heating filament and an antenna filament are connected and the heating filament is used as an auxiliary antenna filament. In the second type, for example, as shown in FIG. 1, a heating line 2 and an antenna line 3 are provided independently on a rear window glass 1.

Each function is provided separately.

However, in the first type described above, it is necessary to prevent the received radio waves from passing through the ground of the heating wire and flowing to the earth, and the direct current supplied to the heating wire must be used to power the radio receiver. It is necessary to prevent it from flowing to the terminals.

For this reason, the circuit becomes very complicated, and the feeder line has 3
When a thin coaxial cable such as O-2V was used, there was a risk of a short circuit accident due to the direct current during anti-fog heating. Another drawback is that radio noise is generated while the heating wire is being energized.

On the other hand, although the second type does not have the drawbacks of the first type, it has a major drawback in that the average gain for FM broadcast waves and AM broadcast waves is low.

In particular, when receiving FM broadcast radio waves, the directional characteristics are strong as shown in FIG. 2, and depending on the direction of the vehicle, the gain decreases, making it difficult to receive FM broadcasts. In addition, Figure 2 shows the gain of the conventional whip antenna
This is a directional characteristic diagram of the antenna in Fig. 1 when B is set, and F is
indicates the direction in which the vehicle is fixed, and the radial direction indicates the direction in which the radio waves arrive.

Also, curve A is 80 MHz, curve opening is 83 MHz, and curve C is 86 MHz.

Indicates when FM radio waves are received.

The present invention improves the average gain for FM broadcast waves not only in Japan but also in the United States and Europe in the second type in which the heating strip and the antenna strip are provided independently, and also improves the directivity characteristics. The purpose of this invention is to provide a glass antenna for a vehicle, which is installed on the window glass surface of a vehicle. a second antenna having at least a horizontal portion extending in the horizontal direction connected to one side of the vertical portion; and a horizontal portion extending in the horizontal direction connected to the other side of the vertical portion; and a third part having a folded part whose end part is folded back.
From the second antenna, a lead-out point to the feeding point is provided at the vertical part connecting the horizontal part and the folded part of the third antenna, and the second antenna is connected to the second antenna. This is achieved by arranging the third antenna asymmetrically.

The present invention will be explained below based on one drawing.

FIG. 3 shows a glass antenna showing the first embodiment of the present invention.
The antenna pattern is particularly suitable for receiving FM broadcasts, and 1 is a base glass forming the rear window of a car, for example, and 2 is a heating strip provided on the glass plate 1.

Reference numeral 2 denotes a T-shaped first antenna consisting of a horizontal portion 4 and a vertical portion 5 provided above the heating line 2 on the plate glass surface.

6.7 horizontal parts 6a, 7a and folded parts 61)
, 7b. A lead-out point 9 to the feed point 8 in the third antenna is provided in the vertical part 7C connecting the horizontal part 7a and the folded part 7b of the third antenna 7, and the lead-out point 9 is connected to the feed point 8 by conductive a10. Connected.

FIG. 4 shows a glass antenna showing a second embodiment of the present invention, and FIG. 5 shows a glass antenna showing a first embodiment of the invention, and the reference numerals indicate the same ones as in FIG. 3 (first embodiment).

When the vehicle glass antenna of the present invention receives FM broadcast waves, the T-shaped first antenna acts as a main antenna over the entire FM frequency range.

T' and 7. provided on one side of the vertical part of the main antenna. A second antenna with a horizontal section that also extends horizontally connects the vehicle body with direct waves.

It eliminates the phase difference between waves reflected by buildings, human bodies, etc., improves the directivity characteristics, and also improves the average gain.
The impedance of the antenna is converted to the impedance of the feeder m (coaxial cable) by the third antenna, which is provided on the other side of the vertical part of the main antenna and has a horizontal part extending in the horizontal direction and a folded part where the end part is folded back. (7
5Ω), thereby increasing reception sensitivity.

In a glass antenna for a vehicle having such a configuration, the glass dimensions shown in Fig. 3 are A=1.100, A'
= 1,450 Same, B = 590 theory, the dimensions of each part of the antenna are M = 520 @ B, n = 550 mm, 1
=40mm, d==IOB, e==506. f
=25mm, y=530na, S=256°C=
2am, g=25M+Im, n=25111
When we measured the directivity characteristics of the antenna with 40M, we obtained the characteristics shown in Figures 6, 7, and 8. ε1) Figure 6 shows 80MH2, Figure 7 shows 83MH2, Figure 8 shows the FM band directivity diagram of 86MH2K as a solid line (the dotted line shows the directional characteristic when there is no whip antenna with a length of 1m, and the dashed line shows the directivity when there is no second antenna). As is clear from FIGS. 7 and 8, the glass antenna of this example can obtain extremely good omnidirectionality for radio waves arriving from any direction. Also, the reception gain of this example is Figure 6, Figure 7,
It can be seen that they are similar when compared with the whip antenna in Figure 8, but if the average gain in the FM band is expressed as the gain difference when the 11th gain of the conventional glass antenna in Figure 1 is 10 dB. +7.0dB at 80MHz, 83MH2
+5.2 dB at 86 MHz, +6 at 86 MHz
．． 4dB.

The average was +6.2dB, which is a significant improvement.

Recognize.

In addition, in the antenna pattern of the first embodiment, when there is no T-shaped first antenna 2, when there is no second antenna 6, or when power is supplied by an FF conductive wire instead of the third antenna 7. of.

The average gain of the horizontally polarized FM band is measured astronomically and is expressed as a gain difference when the gain of the antenna of the first embodiment is OdB.
T-shaped first antenna? (second antenna 6
and third antenna 7 only), -10,3 dB at 80 MHz, -4,9 dB at 83 MH2
B, -4.8 dB at 86 MHz, average -
It can be seen that the 9th first antenna of 6.7 clB contributes very greatly to the gain improvement and is the main antenna.

Next, if there is no second antenna 6 (if only the first antenna? and third antenna 7), in SOMH2 -
2,6 dB, -1,6 dB at 83 MH2.

It contributes to gain improvement of -1.2 dB at 86 MHz and -1.6 dB on average, and if you look at the directivity diagrams without the second phase adjustment antenna 6 in Figs. 6, 7, and 8. The dip in gain is deep, and this is thought to be based on the phase difference between the direct wave and the indirect wave caused by the ground, the vehicle body, etc., and the second antenna for phase adjustment of the present invention works to eliminate the dip. It can be seen that this contributes to improving the directional characteristics.

Next, when feeding only with a conductive wire instead of the third antenna 7, -7.0 dB at 80 MH2, 83 M
-8,2 dB at Hz, - at 86 MH2
3,4(tB.

The average value is -6.2 dB, and the third antenna contributes to the gain improvement.When we measured the antenna impedance at the feeding point when there was a third antenna (for comparison, the third antenna is shown in parentheses). This shows the impedance when there is no power supply, that is, when power is supplied only by conductive wires.)
At 80MHz, embryo (net resistance) = 172Ω (
12Ω), Xe (reactance, + is @ row property, - is capacitance) = +68Ω (+1419), Rs = 540 (504Ω) at 83MH2.

XEl = -40Ω (-4869), R8 = 560 (133Ω) at 86MH2, Xe = OΩ (-241Ω
) and the pure resistance Rs is 75Ω.

, and the reactance l
It can be seen that it works by stably matching the impedance and fully demonstrating the unique characteristics of the antenna.

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

In addition, for comparison with the glass antenna of the present invention, the shape and dimensions (1
-y=530w, d=g=25m+n, and other dimensions are the same as in the first embodiment. ), the second and third antennas are provided symmetrically, and the lead-out point to the feed point is provided in the vertical part connecting the horizontal part and the folded part of the third antenna, as in the first embodiment. When the average gain in the horizontally polarized FM band was measured by -3,0 dB at 86 MH2 -4,3
dB, the average gain is -3.6 dB, and the second.
It can be seen that it is better to make the third antenna asymmetrical.

Next, FIG. 4 shows a second embodiment in which the second and third antennas are arranged alternately as a modification of the first embodiment, and the dimensions of each part shown in FIG. = 1, 10
0mm, N=1.450mm, B=590vr
m,! A=5401TTjn, L=550yB,
1=y==530mm, (1=g=30
1Lm.

e'=n=30+rs, f'=s==30m,
The average gain in the FM band was measured using C=2omffl and h=40th tone, and it is expressed as the gain difference when the gain of the antenna of the first embodiment is OdB.
-0.7dB at 80MH2, '83 MHz
-0.5dB at 86MHz -0.3dB at 86MHz
dB, and an average of -0.5 dB.

Next, the glass antenna shown in FIG. 5, which shows the third embodiment of the present invention, is the antenna of the first embodiment in which the second antenna is configured only by the horizontal part without folding back the end part.
FM with L=530fi and other dimensions (glass and antenna) the same as in the first embodiment.
When the average gain of the band is measured and the gain of the antenna of the first embodiment is OdB, the gain difference is -1.3 dB at 80 MHz2 and -1.0 dB at 83 MHz.
, -1,24B at 86MH2, average -1,2d
It can be seen that the result is B, showing the same characteristics.

The above embodiment is a glass antenna suitable for receiving domestic FM broadcasts of 76 MH2 to 90 MHz, but the glass antenna of the present invention is not limited to domestic use, and is suitable for receiving 88 MH2 to I08 MH2 in the United States and Europe. It is also suitable for receiving FM broadcasts.

For example, in the antenna pattern of Fig. 5 (third embodiment), the F
The actual measurement of the average gain in the M band and the gain difference when the gain of the conventional glass antenna in Figure 1 is OdB is 90MH.
+4.5d at 2, B, + at 100 Mn2
2.5eLB, +3.1dB at 108MH2
It can be seen that there is an improvement of +3.4 dB on average.

In the above example, the effect of this example was explained by specifying the dimensions of each part of the antenna strip and actually measuring the characteristics of the antenna. However, the dimensions of each part of the antenna strip are The optimal value varies depending on the type of car (opening, angle of addition of crow, length of feeder, arrangement rrH!' Sen D1, etc.), and 76 Ml (z ~ 9
When the FM wave at 0 M'H2 is <H i: ;, the length M of the horizontal part that mainly operates as the main antenna is, for example, assuming the wavelength of the FM broadcast frequency as λ, and (λ/4
)α±(λ/20)α(αt: TThe wavelength shortening rate of the glass antenna is approximately 0.7) In other words, in the range of 450 to 750 m, the length for phase adjustment is the same as 1M, for example, (λ/4)α±(λ/20) a exactly 450
In the range of ~750 ror, y of the impedance coupling antenna is ((λ/8)σ−(λ/20)c
l ) ~ ((λ/4)a+(λ/20)α), that is, 2
In the range of 00 to 750 rnIn, the capacitance is increased for the long folded part for phase adjustment, and the impedance has an effect over a wide band with less change, but in this case, when ■・ is the resonance length It is better not to fold back, but in other cases it is better to fold within the range of 300 rIa or less, and other d,, e', f, S, C,
As for the invasion of g, n, and h, the optimum values may be selected as appropriate within a range of at least 3 or more so as to reduce the stray capacitance with elements on adjacent parallel sides.

Although the present invention has been described above with reference to preferred embodiments, the antenna of the present invention is not limited to these embodiments, and the following modifications can be made.

(As shown in Figures 9, 10, and 11 [r, the first T-shaped main antenna may have its horizontal portion composed of two or more filaments; Figure 9), The ends may be folded back (FIG. 10).

Furthermore, the vertical portion may also be configured with two lines instead of one so that the T-shape forms a roof (FIG. 11).

(2) Regarding the folding of the second antenna, it is better not to fold it back when L is the resonance length as described above, but it is better to fold it in other cases.

The horizontal portions of the +31 m2 antenna and the third antenna extending in the horizontal direction are formed in a straight line as in the first and third embodiments, or are formed in a staggered manner as in the second embodiment. Of course, they may be placed on different levels.

In the embodiment 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.

Further, in the embodiment of the present invention, an anti-fog antenna having heating stripes 2 on the rear glass of an automobile is shown, but the heating strip may not be provided, and the antenna of the present invention may be provided on the windshield.

As described above, the glass antenna of the present invention has the characteristics of a separate type that does not connect with the heating wire, and also eliminates the drawbacks of the separate type, and is suitable for use in Japan (76 MHz to 90 MHz).
) as well as the United States and Europe (88MHz to 108MHz
), the average gain is high over the entire FM broadcast range, and the directivity characteristics can also be improved.

[Brief explanation of drawings]

Figure 1 is a plan view of a conventional glass antenna, and Figure 2 is a top view of a conventional glass antenna.
3, 4, and 5 are plan views of a glass antenna showing an embodiment of the present invention.
Figures 7 and 8 are directional characteristic diagrams at 80 MHz, 83 MHz, and 86 MHz, respectively, in Figure 3 (first embodiment) (the dotted line is the 1m-long rear whip antenna, and the one-dot chain line is the one in the first embodiment). 9, FIG. 10, and FIG. 11 show modifications of the first antenna of the present invention. DESCRIPTION OF SYMBOLS 1... Plate glass, 2... Heating wire, 2... First antenna 4... Horizontal part, 5... Vertical part, 6
...Second antenna 6a...Horizontal part, 7...
-Third antenna, 7a...Horizontal part 7b...Folded part, 7c...Vertical part, 8...Feeding point 9.
... Drawing point patent applicant Central Glass Co., Ltd. agent Patent attorney Sakae Sakamoto -1 Figure 1 Figure 3 Figure 8 F Figure 9 Figure 10 Figure 1 =] --- 13-

Claims (2)

[Claims] (1) In a glass antenna for a vehicle in which an antenna strip is provided on a plate glass surface, the antenna includes a T-shaped first antenna consisting of a horizontal part and a vertical part, and at least one antenna connected to one side of the vertical part. A second antenna having a horizontal part extending in the horizontal direction, and a third antenna having a horizontal part connected to the other side of the vertical part and having a folded part obtained by folding back the end of the horizontal part. , a lead-out point to the feeding point is provided in the vertical part connecting the horizontal part and the folded part of the third antenna, and the second and third antennas are provided. A glass antenna for vehicle weight that is characterized by its asymmetrical arrangement. (2) The length of the folded part of the third antenna (Al1
)a±(λ/20)a (λ゛Wavelength of the received FM frequency; a wavelength shortening rate of the glass antenna) for an axle according to claim 1.