JPH0373169B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an antenna glass in which an antenna wire is disposed on the window glass of an automobile, and is particularly suitable for reception when FM broadcast radio waves to be received span a wide band on the high frequency side. This invention relates to an antenna glass for automobiles that maintains good performance. [Prior Art] In general, whip antennas are widely used as antennas for automobile radio receivers, but since this type of antenna becomes an external protrusion relative to the vehicle body, as a means to avoid this, ,
Recently, so-called antenna glasses, in which antenna wires are disposed on the rear window glass or front window glass of automobiles, have begun to appear. Taking a rear window glass as an example of this type of antenna glass, for example, as shown in FIG. 11, the rear window glass 1 of an automobile is usually provided with a heater wire H as a heater member for defogging. Up,
An antenna wire A for receiving FM broadcast waves is provided, for example, in the upper region of the rear window glass 1 so as not to interfere with the heater wire H. This type of antenna wire A connects one end of the main antenna wire 3 extending along the substantially horizontal direction of the window glass 1 to the feeding point 2, and has the main antenna wire 3 above the main antenna wire 3. Sub-antenna wires 4 are arranged approximately in parallel, and the intermediate portion of the sub-antenna wires 4 and the other end of the main antenna wire 3 are connected by a connecting wire 5 for phase adjustment. It is. In FIG. 11, reference numeral 6 denotes a substantially inverted L-shaped auxiliary antenna wire provided at one end of the main antenna wire 3. For example, an antenna wire A1 for receiving AM broadcast radio waves is disposed below the antenna wire A, and this type of antenna wire A1 includes, for example, a plurality of antenna wires substantially parallel to the main antenna wire 3. Along with arranging 7 and 8,
Each antenna wire 7, 8 is connected by a suitable connecting wire 9. In such antenna glass, for example
The phases of the sub-antenna wire 4 and the main antenna wire 3 are matched by the connecting wire 5 in the low frequency band of FM broadcast radio waves, and the phases of the sub-antenna wire 4 are matched in the high frequency band of the FM broadcast radio wave. If the connecting wire 5 is made to function as a reactance element, the main antenna wire 3 and the sub-antenna wire 4 can be
It is possible to divide and receive the FM broadcast radio wave band as appropriate, and the AM antenna wire A1, together with the main antenna wire 3, can secure a certain reception area as a whole. This makes it possible to receive the information efficiently. [Problems to be solved by the invention] However, with such conventional antenna glass, it is difficult to obtain a certain degree of sufficient gain and omnidirectionality for the domestic FM broadcast radio wave band (76 to 90 MHz). However, it has been found that it is difficult to obtain sufficient gain for the high-frequency and wide-band FM broadcast radio wave band (88 to 108 MHz) such as in the United States. In order to solve these problems, it is possible to improve the antenna gain by using an amplifier for amplification, but using an amplifier inevitably causes the problem of cross modulation to become noticeable.
Not desirable as a solution. For this reason, the inventor of the present application has been studying various antenna patterns that can obtain high gain without an amplifier, and has come up with the present invention. [Means for Solving the Problems] The present invention has been made by focusing on the above problems, and is applicable to cases where the FM broadcast radio wave band to be received is high frequency and covers a wide band. Another object of the present invention is to provide an antenna glass for automobiles that allows high gain to be obtained without using an amplifier. That is, the present invention provides an automobile antenna glass in which an antenna wire is disposed on the window glass of an automobile, in which a pair of basic antenna wires having different frequency characteristics are provided as the antenna wire, and at least one of the basic antenna wires is It is made up of two substantially T-shaped auxiliary antenna wires branched from each other. In such technical measures, there are no particular restrictions on the type of window glass for a car, but a rear window glass is preferable from the viewpoint that it does not significantly affect visibility from inside the vehicle. In addition, the materials for the antenna wire include conductive metal powder such as Ag, Al, Pd, or other conductive material powder, glass frit,
A conductive paste is produced by mixing a binder and other desired additives, and the conductive paste is baked onto a glass plate in the form of thin stripes in a predetermined pattern using a screen printing method or the like. In addition, various other conductive materials can be used as appropriate. Furthermore, as a mounting surface for the antenna wire, for types where the window glass is made up of a single glass plate, the antenna wire is usually attached to the surface of the window glass, but it is possible to attach multiple glass plates together. In the case of a type of window glass that is made of so-called laminated glass, antenna wires may be interposed not only on the surface of the window glass but also between the glass plates.
In this case, the antenna wire is not exposed on the window glass surface, which is desirable from the viewpoint of protecting the antenna wire. Furthermore, regarding the pattern of the antenna wire, as long as it has at least a basic pattern consisting of a pair of basic antenna wires and two T-shaped auxiliary antenna wires, other appropriate auxiliary antenna wires may be attached. However, at least the effective length of the above-mentioned basic antenna wire should be set so that the desired receiving frequency band can be received with good performance. It is particularly preferable that the length be within the range of the wavelength of the desired frequency x 1/4) x (shortening rate of the antenna glass) to (the wavelength of the desired frequency x 1) x (the shortening rate of the antenna glass). For example, one of the above basic antenna wires is set to {2780 mm/4 (1/4 wavelength of 108 MHz) to ensure an effective length corresponding to the high band (98 to 108 MHz) of the FM broadcast radio wave band to be received. ×0.64 (shortening rate of antenna glass)} ~ {3060
mm (one wavelength of 98 MHz) x 0.64 (same as above)}, that is, approximately 440 mm to 1960 mm. Regarding the other basic antenna wire, the range determined by In order to secure the effective length corresponding to the band range (88 to 98MHz),
wavelength) x 0.64 (same as above)}, i.e., abbreviated
A range of 490 mm to 2180 mm is particularly preferred.
In addition, it is necessary to design the approximately T-shaped auxiliary antenna wire so as to expand the practical reception area of the basic antenna wire, and specifically, it is necessary to design the substantially T-shaped auxiliary antenna wire in such a way that component 50~1000mm
In addition to setting the vertical component in the range of 5 to
It is particularly preferable to set it within a range of 100 mm. Furthermore, when attaching an auxiliary antenna wire in addition to the basic pattern of the antenna wire, the design of the auxiliary antenna wire may be changed as appropriate, such as a substantially T-shaped one or a substantially L-shaped one. ,
In order to further improve the matching with the load impedance of a radio receiver or the like, a matching element for input impedance matching may be interposed between the basic antenna wire and the feeding point. [Operation] According to the technical means as described above, the above-mentioned abbreviation T
Two auxiliary antenna strips are provided on one of the basic antenna strips, so even if radio waves are re-radiated from one of the basic antenna strips during reception, most of these re-radiated radio waves are from the auxiliary antenna strip. Since the antenna is received again by the antenna wire portion, the radio wave loss is suppressed accordingly, and as a result, the effective reception area of the corresponding basic antenna wire portion is expanded and the gain of this basic antenna wire portion is increased. It is thought to have the effect of increasing [Example] Hereinafter, the present invention will be described in detail based on the example shown in the accompanying drawings. ◎Example 1 In this example, as shown in Fig. 1, an anti-fog heater wire H is provided approximately at the center of the rear window glass 1 of an automobile, and a heater wire H is placed above the heater wire H. On the surface of the upper region of the window glass 1,
An antenna wire A having a predetermined pattern printed by baking with a conductive paste, for example, a silver paste is disposed. This antenna wire A includes a first basic antenna wire 10 arranged near the upper side of the window glass 1 and a second basic antenna wire 20 arranged below this basic antenna wire 10. We are prepared.
The first basic antenna wire 10 is a window glass 1
It is composed of a lateral filament 11 extending substantially in the lateral direction, and a branched filament 12 branched from the middle of the lateral filament 11 and disposed substantially parallel to the lateral filament 11, The above second basic antenna wire 20
, a horizontal filament 21 extending substantially in the lateral direction of the window glass 1, and one folded filament 22, 23 which is folded back in a substantially inverted L shape from both ends of the horizontal filament 21 and spaced apart from each other. It is configured. Substantially T-shaped auxiliary antenna wires 13 and 14 are connected to the tip and intermediate portions of the branched wire 12 of the horizontal wire 11 of the first basic antenna wire 10, respectively. A substantially T-shaped auxiliary antenna wire 24 is connected to a substantially central portion of the horizontal wire 21 of the second basic antenna wire 20 . Further, a feed point 2 is set on one side below the second basic antenna wire 20, and a matching element 3 whose tip is bifurcated is provided at the feed point 2.
0 is connected and further branched matching element 3
0 is connected to the horizontal filament 11 of the first basic antenna filament 10 and the horizontal filament 21 of the second basic antenna 20, respectively. This matching element 30 is adjusted to have an appropriate impedance in order to facilitate matching between the load impedance of a radio receiver or the like and the input impedance of the antenna wire A. More specific dimensions of each part are as follows.
Note that the symbol M in FIG. 1 indicates the vertical center line of the window glass 1. a1=540, a2=495, a3=270, a4=150, a5=
330, a6=175, a7=150, a8=30, a9=30, a10
=440, a11=540, a12=50, a13=90, a14=30,
a15=30, a16=30, a17=400, a18=500, a19=
105, a20=30, a21=60 (unit: mm) Comparative Example This comparative example is equipped with the conventional antenna pattern shown in FIG. 11, and the specific dimensions are set as follows. c1=200, c2=400, c3=480, c4=10, c5=30,
c6 = 50, c7 = 60 (unit: mm) Comparison of reception performance between Example 1 and Comparative Example Now, for a car equipped with the antenna glass according to Example 1 and Comparative Example, as shown in Fig. 2, , while rotating the vehicle C 360 degrees from the reference position S ₀ , _a predetermined frequency (88
FM broadcast radio waves (~108 MHz) were transmitted in a uniform electric field of 60 dBμ/m, and the reception sensitivity level (unit: dBμ) corresponding to each position of the car C was measured. As a result, the average receiving sensitivity level (MEAN) and directivity (minimum receiving sensitivity level subtracted from the average receiving sensitivity level) of Example 1 and Comparative Example are shown in the table below, and the average receiving sensitivity level (MEAN) at each frequency is shown in the table below. The changes in the sensitivity level are shown in the graph in Figure 3, and the changes in directivity at each frequency are shown in the graph in Figure 4.
Shown in the graph diagram of Figure. In FIGS. 3 and 4, □ marks indicate the results of Example 1, and x marks indicate the results of Comparative Example.

[Table] When the receiving performance of the antenna glass according to Example 1 is evaluated based on the above table and graph, it is found that the receiving sensitivity level of this example is 3.9 dBμ higher on average than that of the comparative example. It is understood that this antenna pattern allows a high-gain antenna glass to be obtained without an amplifier. In addition, although the directivity of Example 1 is slightly sharper than that of the comparative example, it is not extremely sharp, so there is a situation where the omnidirectionality of the antenna glass of the above example is extremely impaired. is also avoided. ◎Example 2 As shown in FIG. 5, the antenna wire A in this example has a pair of basic antenna wires 10, 20 different from those in Example 1, and each basic antenna wire 10, 20 has a window. It is composed only of lateral filaments 11 and 21 extending in the substantially lateral direction of the glass 1, and the lateral filament 11 includes a substantially T-shaped auxiliary antenna filament 1.
3 and 14 are connected, and the horizontal filament 2
One approximately T-shaped auxiliary antenna wire 24 is connected to the tip of the antenna. A performance test similar to that of Example 1 was conducted for this example as well, and it was found that the antenna glass according to this example could be used without an amplifier in the FM broadcast radio wave band (88 to 108 MHz) without significantly impairing the omnidirectionality of the antenna glass. It has been found that sufficient gains can be obtained. ◎Modifications Figures 6 to 10 show modifications of each of the above embodiments, and each of the above embodiments is only for receiving the FM broadcast radio wave band. As shown, a substantially T-shaped AM antenna wire A2 is provided below the second basic antenna wire 20.
may be arranged in close proximity to the heater wire H, and the AM antenna wire 2 and the heater wire H may be configured to receive the AM broadcast radio wave band, or the heater wire H may be arranged in the It is also possible to provide a unique AM antenna wire without using it also as an antenna. Further, as the auxiliary antenna wire, for example, as shown in FIG. 7, the horizontal wire 1 of the first basic antenna wire 10
A folded wire strip 15 may be further attached to one end of the antenna wire 1, or the design may be changed as appropriate, such as by forming an appropriate folded portion 16 on the approximately T-shaped auxiliary antenna wire strip 13, as shown in FIG. No problem. Furthermore, in each of the above embodiments, the antenna wire A is disposed above the heater wire H, but as shown in FIGS. 8 to 10, the antenna wire A of each pattern is disposed below the heater wire H. may be arranged. In this case, it has been experimentally shown that especially when applied to the rear window glass of a lift bag or hatchback type that can be opened/closed, particularly good reception performance can be obtained compared to the case where it is placed above the heater line H. has been confirmed. Furthermore, the above basic antenna wire 1
A matching element 30 for impedance matching is interposed between 0 and 20 and the feeding point 2, but by appropriately changing the antenna pattern, it is possible to match the load impedance of the radio receiver etc. and the input impedance. Of course, if this can be done easily, the basic antenna wires 10 and 20 may be designed to be directly connected to the feeding point 2 without particularly using the matching element 30. [Effects of the Invention] As explained above, according to the automotive antenna glass according to the present invention, even when the FM broadcast radio wave band to be received spans a wide band on the high frequency side, sufficient reception can be achieved without an amplifier. Gain can be ensured, and the receiving performance of the antenna glass can be kept good accordingly.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing Example 1 of the automotive antenna glass according to the present invention as seen from the interior of the vehicle, and FIG. 2 is an explanatory diagram showing an example of a method for measuring the reception performance of the antenna glass according to Example 1. Figure 3 is a graph showing changes in the average reception sensitivity level in each frequency band of Example 1 and Comparative Example (conventional example), and Figure 4 is a graph showing changes in average receiving sensitivity level in each frequency band of Example 1 and Comparative Example. A graph diagram showing changes in directivity, FIG. 5 is an explanatory diagram similar to FIG. 1 showing Example 2 of the automotive antenna glass according to the present invention, and FIGS. 6 to 10 are graph diagrams showing the automotive antenna glass according to the present invention. FIG. 11 is an explanatory view similar to FIG. 1 showing various modifications of the antenna glass, and FIG. 11 is an explanatory view showing an example of a conventional antenna glass for an automobile as seen from the inside of the vehicle. [Explanation of symbols], A... antenna wire, 1...
Rear window glass (window glass), 2...Power supply point, 10,
20... Basic antenna wire, 13, 14, 24...
...Auxiliary antenna striations.

Claims (1)

[Scope of Claims] 1. An antenna glass for an automobile in which an antenna wire is disposed on a window glass of an automobile, wherein the antenna wire has a pair of basic antenna wires having different frequency characteristics, and at least one of the basic antenna An antenna glass for an automobile, characterized in that the antenna wire is provided with two approximately T-shaped auxiliary antenna wires. 2. An antenna glass for an automobile according to claim 1, wherein one or more approximately T-shaped auxiliary antenna wires are branched from the other basic antenna wire. 3 The above-mentioned basic antenna filament consists of a horizontal filament extending substantially in the lateral direction of the window glass, and a horizontal filament that is folded back toward the center of the horizontal filament near both ends of the horizontal filament, and the tips thereof are spaced apart from each other. An antenna glass for an automobile according to claim 1 or 2, characterized in that the antenna glass has a folded line. 4. The automotive antenna according to any one of claims 1 to 3, wherein the basic antenna wire is connected to the feed point via a matching element for input impedance matching. glass.