JPH01120903A - Window glass antenna for automobile - Google Patents

Abstract

PURPOSE:To obtain a broad band nondirectional antenna with less occupied area of the face of glass by providing a zigzag conductor which forms triangular waves whose amplitude is gradually increased and a slit dividing the zigzag conductor into small and large amplitude parts. CONSTITUTION:The conductor pattern of the title antenna is basically formed for an antenna of a logarithmic period. That is, an open angle alpha is set with respect to the origin O at both sides of a horizontal axis X passing through the origin O, and the zigzag antenna (or triangle waveform antenna) where apexes A, B, C... of triangles are connected one after another by a conductor 1 is formed within the open angle. In selecting the length of the conductor 1 tying the apexes A, B, C... or the amplitude of a triangle wave so as to be increased at a prescribed rate, the characteristic is alike a logarithmic period antenna and the antenna is usable at a broad band. Since the antenna consists of horizontal and vertical conductor components, the antenna copes with both horizontal and vertical polarized waves. In constituting said antenna in a way that the use at a high band with a slit 6 given to the conductor 1 and the use at a low band without the slit 6 to the conductor 1 are switched electrically, the antenna with low loss feeding at the broadest band is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to automotive window glass antennas, and in particular to broadband VHF or UHF antennas.

[Summary of the invention]

This is an antenna that has a triangular wave-shaped zigzag conductor with gradually increasing amplitude attached to the window glass of a car, and exhibits broadband and omnidirectional characteristics.

(Prior Art) A well-known AM or FM broadcasting antenna for a car is one in which a conductive pattern of the antenna is formed by printing and baking a conductive paste on a window glass.

Various attempts have also been made to similarly form VHF and UHF antennas for in-vehicle telephones using printed conductors on glass surfaces.

[Problem that the invention seeks to solve]

Since the area of an automobile window glass is limited, it has been extremely difficult to obtain a broadband and omnidirectional VHF or UHF antenna using a printed conductor.

In view of this problem, it is an object of the present invention to obtain a wideband, omnidirectional antenna that occupies a small area on a glass surface.

[Means for solving problems]

The automobile window glass antenna of the present invention includes a triangular wave-shaped zigzag conductor whose amplitude gradually increases. An improved windowpane antenna of the present invention which achieves the same object also includes a slit that divides the zigzag conductor into a small amplitude section and a large amplitude section.

[Effect]

An antenna characteristic that combines characteristics similar to a logarithmic periodic antenna and characteristics similar to a zigzag antenna can be obtained.

Furthermore, by providing slits to connect and disconnect the separated conductors, it becomes possible to switch between local conductors and the entire conductor, thereby further widening the bandwidth.

〔Example〕

FIG. 1 shows the conductor pattern of the automobile window glass antenna of the present invention. This antenna is for receiving TV broadcasts, and
It is used in the low band 90 to 110 MHz and high band 170 to 230 MHz of the HF band. The conductor pattern basically resembles a log-periodic antenna. That is,
Set an opening angle α with respect to the origin O on both sides of the horizontal axis X passing through the origin 0, and within this opening angle, the vertices A, B,
A zigzag antenna (or triangular wave antenna) is formed by connecting C-.

If the length of the conductor 1 or the amplitude of the triangular wave connecting the vertices A, B, C...--11 increases at a predetermined ratio, a log-periodic antenna-like structure can be created. showing the characteristics,
Can be used in wideband. In addition, a zigzag antenna with a series of triangular waves consists of a horizontal conductor component and a vertical conductor component, so
It has the feature of being able to handle both horizontal and vertical polarization.

Each vertex A, BXC in Fig. 1.
The distance (height) Y7 of ---- from the X-axis is a function of the opening angle α and the position from the origin O along the X-axis.

In the example of FIG. 1, for example, at α-30°, each vertex A, B, C・−1 −−−−−−−−
−・・・・・position is determined.

The antenna pattern in Fig. 1 consists of a pair of antennas la and 1b that are symmetrical with respect to the origin O, and as shown in Fig. 2, the conductor ends on the origin O side are used as feeding terminals 2a and 2b, and are balanced via a parallel feeder. Use with power supply. In the example in Figure 2,
Such an antenna conductor 1 is arranged below the anti-fog heater wire 4 of the rear window glass 3. Note that the antennas 1a and 1b
In this example, each horizontal total length a is about 37 cm.

Figure 3 shows an example in which an unpaired zigzag log-periodic antenna is attached to the 1J quarter window glass 5. In this case, the starting end of the conductor 1 is used as the feeding terminal 2C and is used for unbalanced feeding via a coaxial feeder. .

Incidentally, conductors l similar to those shown in FIG. 3 may be attached to the rear quarter window glasses 5 on both sides to form a diversity reception system.

FIG. 4 shows an example in which a zigzag log-periodic antenna is constructed by a pair of antennas 1a and 1b which are made axially symmetrical (vertically folded) with respect to the antenna conductor 1 shown in FIG.

Figure 5 shows the TV band Coro-Hand 90~ of the antenna in Figure 1.
110 MHz), and FIG. 6 shows the directional characteristics in the TV high band (170 to 200 MHz). As shown in each figure, the zigzag log-periodic antenna shown in Figure 1 exhibits almost omnidirectional characteristics without a large dip, and T
It can be seen that it exhibits wideband characteristics covering almost the entire V broadcast band (90 to 230 MHz). However, the gain is higher in the low band due to the input impedance.

FIG. 7 is a Smith chart showing the impedance characteristics of the antenna shown in FIG. 1, and the normalized characteristic impedance Z0 in this case is 100Ω. Also, when the standing wave ratio SWR of this antenna was measured, it showed 3.7 to 5.3 in the low band and 3.4 to 9.4 in the high band. That is, in the low band, the impedance matching with the feeder was good, and the glass antenna -C was within the standard practical range.

For boat fishing, if you change either the number of triangular waves (number of elements), opening angle α or logarithmic period γ of the antenna shown in Figure 1, and change the length of one segment of conductor 1, you can adjust the low frequency limit or The high range limit is extended. However, if the low range is extended, for example, high range deterioration (lower high range limit) is unavoidable. In other words, this type of log-periodic antenna has the characteristic that the frequency bandwidth (ratio of the highest frequency to the lowest frequency) is constant, and if one of the low band and high band characteristics is improved, the characteristics of the other will deteriorate. Tend.

Therefore, an attempt was made to improve the high frequency characteristics by inserting a slit in the middle of the antenna conductor 1 shown in FIG.

That is, a two-width slotted slot 6 was inserted at position S in FIG. 1 to divide the conductor into an inner conductor 1m and an outer conductor 1n.

Naturally, the action of the antenna becomes dominant on the inner conductor 1m on the feeding point side, and the band shifts to the higher frequency side.

FIGS. 8 and 9 are directional characteristics diagrams in the TV band colo-band and high band when the slit 6 is provided in the antenna shown in FIG. 1. As can be seen from these figures, the low band characteristics are significantly degraded, but the high band gain is significantly improved compared to the case without the slit 6 (FIG. 6). Also, as shown in the Smith chart in Figure 10, the biband normalized impedance is at the matching point (Z/ Zo = 1., O) compared to the case without the slit 6 (Figure 7).
It can be seen that the standing wave ratio (SWR) of the antenna pattern shown in FIG. 1 with and without the slit 6 is compared as shown in the following table.

SWR That is, bi-band SWR when slit 6 is inserted.
was extremely good. On the other hand, the SWR in the low band without the slit 6 is within the practical range, as previously reported.

As described above, if the conductor l is configured to electrically switch between the state in which the slit 6 is inserted and used in the high band, and the state in which the slit 6 is removed and used in the low band, the antenna with the widest band and low loss can be obtained. It turns out that you can get it.

To achieve this, a switch element connecting the slits 6 may be used. FIG. 11 shows an example in which a diode 7 is used as a switch element or switch member. A switching voltage is applied to this diode 7, and when the diode 7 is turned off, the diode 7 is set to high impedance to separate the outer conductor In and the inner conductor 1m of the antenna conductor 1, and when it is turned on, the diode 7 is set to a low impedance and the conductors In and 1m are connected. . The switching voltage can be automatically generated in connection with the TV channel selection operation, and the switching voltage can be generated automatically in connection with the TV channel selection operation.
The conductor pattern can be modified to supply this switching voltage through the conductor pattern.

Note that instead of the diode 7, a variable capacitance element such as an ordinary capacitor or a varicap may be used, or an analog switch such as an FET may be used.

FIG. 12 shows the conductor 1 in order to capacitively couple the slit 6.
This is an example in which auxiliary conductors 8m and 8n are extended from the ends of the inner conductor 1m and the outer conductor In in the slit 6 portion, and these are placed close to each other and face each other. By setting the opposing distance and opposing line length of these auxiliary conductors 8m and 8n as appropriate,
In the high band, the 1m inner conductor becomes the main body of the antenna.
In the low band, the inner and outer conductors 1m and In function as conductive antennas due to capacitive coupling between the auxiliary conductors 8m and 8n, so that low-frequency compensation can be performed.

By changing the position S of the slit 6 in Fig. 1, it is possible to arbitrarily shift the reception band of the inner conductor 1m when there is a slit 6 with respect to the reception band of the entire antenna conductor 1 when there is no slit 6. It is. Figure 12 shows state A (local characteristics) with slit 6 inserted at position S shown in Figure 1.
and 0 local characteristic A, which is a frequency characteristic diagram showing the horizontal maximum receiving sensitivity of B (overall characteristic) when Surinoto 6 is eliminated.
is the high band of TV broadcast band (170-230MHz)
The sensitivity decreases rapidly below 170 M)lz. On the other hand, overall characteristic B is low band (90 to 110M
Hz), and the sensitivity gradually decreases above 140M)Iz. Therefore, each characteristic A and B almost overlaps with the high band and low band of the TV broadcast band, and the middle 11
(The area where there are no TV broadcast waves in the range of 1 to 170 MHz almost coincides with the area where the sensitivity of the antenna is reduced.

Note that if the slit 6 in FIG. 1 is placed further outside, the lower limit gain of characteristic A in FIG. 13 will extend further to the lower frequency side. Conversely, if the slit 6 is biased inward, the lower limit to the characteristics will move to the higher frequency side. Moreover, the overall characteristic B without the slit 6 does not change much. Therefore, depending on the purpose, the position of the slit 6 can be determined according to the required band so that characteristics A and B are connected continuously, or so that the characteristics A and B are switched discontinuously with a gap in the middle as shown in Fig. 13. can.

In the above embodiment, the amplitude of the zigzag triangular wave is set to a predetermined ratio γ, but each vertex A, B, C...・
The position of ...-------------- may be determined.

Alternatively, the amplitude or side length of the triangular wave may vary in an arithmetic series. Alternatively, as shown in FIGS. 14A to 14C, a zigzag triangular wave conductor may be formed with a predetermined polygonal line or curve as the outer edge (envelope).

FIG. 14A shows an example in which the amplitude of the triangular wave conductor 1 is increased at a predetermined opening angle and then made constant. Figure 14 B, C
are examples in which the outer edge of the triangular wave conductor l is changed in an exponential curve and a logarithmic curve, respectively.

〔Effect of the invention〕

As described above, the windowpane antenna of the present invention has the characteristics of a log-periodic antenna and a zigzag antenna, so it has a very wide band and is almost omnidirectional, even though it occupies a small area on the glass surface, and has polarization loss. It has the advantage that the characteristics do not change significantly depending on the conditions. According to the second aspect of the present invention, by separating or connecting the conductor 1 at the slit 6, the antenna can be switched between a local antenna with good high-frequency characteristics and a general antenna with good low-frequency characteristics. It is possible to further widen the band.

[Brief explanation of the drawing]

Fig. 1 is a conductor pattern diagram showing an embodiment of the automobile window glass antenna of the present invention, Fig. 2 is a conductor pattern diagram on the rear window glass surface of an automobile, and Fig. 3 is a conductor pattern diagram on the rear quarter window glass surface of an automobile. A pattern diagram, FIG. 4 is a diagram showing a modified example of 1E, FIGS. 5 and 6 are directional characteristics diagrams of the antenna in FIG. 1, FIG. 7 is a Smith chart showing input impedance characteristics, and FIGS. Figure 9 is a directivity characteristic diagram when a slit is made in the antenna conductor in Figure 1, Figure 10 is a Smith chart showing input impedance characteristics, and Figures 11 and 12 are diagrams showing the elements that couple the slits in the conductor. The partially enlarged view shown in Fig. 13 is the TV band roller of the slit antenna.
Frequency characteristic diagram showing band and high band sensitivity, No. 14
Figures A to C are diagrams showing modified examples of the zigzag conductor, respectively. In addition, in the symbols used in the drawings, 1...--------- Antenna conductor 2a
, 2b-Power supply terminal 3--...--Rear window glass 4
・−・・−・・−・−・−Antifog heater wire 5・・−・
・・−・−・・−・−・Rear quarter window glass 6・
・−・・・−・・・−・−−−−,2,IJt7・−
・・−・・−・−・・・・・−Diode 8m, 8n−
It is an auxiliary conductor.

Claims (1)

[Claims] 1. An automobile window glass antenna consisting of a triangular wave-shaped zigzag conductor whose amplitude gradually increases. 2. A triangular wave-like zigzag conductor whose amplitude gradually increases,
An automobile window glass antenna comprising a slit that divides the zigzag conductor into a small amplitude part and a large amplitude part.