JP2001332923A - Film antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the length dimension of a film antenna, to receive the radio wave of a desired frequency band and to simplify a configuration. SOLUTION: A plate-like film antenna element 2 is stuck onto a glass 6 supported by a conductive frame 4, and a power is supplied to these film antenna element 2 and frame 4 by a coaxial cable 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film antenna, and more particularly, to a film antenna mounted on a conductive frame such as a window frame.

[0002]

2. Description of the Related Art A film antenna is one in which an antenna element is formed using a conductive film, and is sometimes used, for example, by sticking it to a window glass or the like. Conventionally, as a film antenna, there is a film antenna configured as a dipole antenna having a length that resonates at a reception center frequency.

[0003]

When, for example, an antenna in the VHF band is constituted by such a dipole type film antenna, it is necessary to set the length of the element of the film antenna to resonate at the reception center frequency in the VHF band. There is. This length was relatively long, and it was difficult to stick it on a window glass or the like. In addition, not only VHF band but UH band
If a film antenna is used to form a common antenna capable of receiving signals even in the F band, the pattern becomes complicated, and it takes time to make the pattern.

An object of the present invention is to provide a film antenna which can receive radio waves in a desired frequency band and has a simple configuration even if the length is short.

[0005]

In order to achieve the above object, the present invention uses a conductive frame as a part of an antenna. That is, the film antenna according to the present invention includes a flat film antenna element attached to a support supported by a conductive frame, and a power supply unit that supplies power to the film antenna element and the frame.
I have it.

In this film antenna, since the power is supplied to the frame and the film antenna element by the feeder, the frame also functions as a part of the antenna. Therefore, even if the length of the film antenna element is shorter than the length for reception in the predetermined frequency band, the frame functions as a part of the antenna, so that reception in the predetermined frequency band is possible.
Therefore, the film antenna can be manufactured small.

[0007] The film antenna element may be formed in a rectangular shape. In this case, the conductive frame is
It has a pair of parallel plate-shaped parallel portions. The film antenna element is arranged parallel to the parallel portion.

In the thus configured film antenna, the plate-shaped parallel portion parallel to the rectangular film antenna resonates with a predetermined frequency and functions as a part of the antenna element. Therefore, even if the same film antenna element is used, the reception frequency band can be changed by changing the length of the parallel portion of the frame to which the film antenna element is attached. Further, since the film antenna element has a rectangular shape, its manufacture is easy.

In the case where the film antenna element is formed in a rectangular shape, the film antenna element is sandwiched in a direction perpendicular to the length direction of the film antenna element, and a rectangular shape having a longer dimension than the film antenna element is provided. A film reflective element having a shape can be attached to the support.

With this configuration, the antenna characteristics can be improved in the vicinity of a frequency band that resonates with the length of the film reflection element, and since the reflection element is in the form of a film, the antenna must be small even if the reflection element is provided. There is no alternative.

In each of the above-described film antennas, the film antenna element may be formed of a transparent conductive film. When a film reflection element is provided, this can also be formed by a transparent conductive film. In these cases, even when the support is made of a transparent material such as a window glass, the film antenna element and the film reflection element do not stand out, and the appearance is not spoiled.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A film antenna according to a first embodiment of the present invention has a film antenna element 2 as shown in FIG. This film antenna element 2 is formed of a transparent conductive film, and is formed in a substantially rectangular shape. The film antenna element 2 is attached to a support, for example, glass 6 supported by the frame 4. Because it is made of transparent conductive film,
Even if the film antenna element 2 is attached to the glass 6, it is not noticeable and does not impair the aesthetic appearance.

The frame 4 is provided, for example, in a window of a house, and has first parallel portions, for example, horizontal portions 4a and 4b, which are arranged parallel to each other and spaced apart from each other. It also has a second parallel portion, for example, a vertical portion 4c, 4d, which is perpendicular to the portions 4a, 4b and spaced apart parallel to each other. These horizontal parts 4a, 4b, vertical parts 4c, 4d
A rectangular glass 6 is supported in a space surrounded by. These horizontal parts 4a, 4b and vertical parts 4c, 4d
It is electrically conductive and its surface may be painted.

The film antenna element 2 has a horizontal portion 4a,
It is attached parallel to 4b and substantially at the center of the vertical portions 4c and 4d. The film antenna element 2 is for receiving television broadcast waves in a plurality of frequency bands, for example, UHF band and VHF band, and has a length dimension of, for example, 100 to 200 mm and a width dimension of, for example, 80 to 1, for example.
00 mm, and is arranged at a position about 30 mm away from the vertical portion 4c. This length is a considerably short length when considered for reception in the VHF band.

A copper foil portion 8 for feeding power is attached to a position near the vertical portion 4c of the film antenna element 2. A power supply unit, for example, a core wire 12 of a coaxial cable 10 is connected to the copper foil unit 8. The outer conductor 14 of the coaxial cable 10 serving as a power supply unit is connected to a window key 16 provided in the vertical part 4c. The key 16 also has conductivity, and is mechanically fixed to the vertical part 4c by the fixing part 16a. The outer conductor 14 is fixed to the fixing portion 16a.
Is joined to. When the fixing portion 16a is not coated, the external conductor 14 is directly screwed to the fixing portion 16 for connection. When the fixing portion 16a is coated, it is indirectly connected. For example, electrostatic coupling is performed.

Since the frame 4 is thus connected to the external conductor 14, the frame 4 functions as an antenna element.
In particular, since the horizontal parts 4a and 4b are arranged in parallel with the film antenna element 2, it is considered that these parts function as antenna elements.

As the frame 4, various sizes can be used. For example, as shown in FIG.
Frame 4 with a length of 850 mm and a height of 300 mm
0, and the length and height are 7 as shown in FIG.
A frame 41 having a length of 10 mm, a frame having a length of 900 mm and a height of 820 mm as shown in FIG. 4C, and having a length and height of 1030 as shown in FIG.
mm frame 43 can be used.

These frames 40, 41, 42, 43
The gain versus frequency characteristics in a state where the film antenna element 2 having a length of 150 mm and a width of 90 mm is attached are indicated by reference numerals a, b, c, and d in FIG. The symbol a indicates the frame 40, the symbol b indicates the frame 41, the symbol c indicates the frame 42,
The symbol d indicates the case where the frame 43 is used. As is clear from FIG. 3, in each case, a gain of a practical level is obtained in the VHF band and the UHF band, and this antenna can be used as a wideband antenna.

If the lengths of the horizontal portions 4a and 4b, that is, the lengths of the frames 40 to 43 are different, the gain versus frequency characteristics are different. In particular, when the frame 42 is used, VH
The gain is greatly improved in the low band of the F band (76 MHz to 108 MHz), and when the frame body 40 is used, the gain is greatly improved in the UHF band (470 MHz to 770 MHz).

Each of the frames 40, 41, 4 shown in FIG.
2, 43, length dimension is 150mm, width dimension is 90m
FIG. 4 shows a directional characteristic diagram at 90 MHz which is a low band of the VHF band in a state where the film antenna element 2 of FIG.
Shown in FIG. 11A shows a case where the frame is attached to the frame 40, FIG. 10B shows a case where the frame is attached to the frame 41, FIG. 10C shows a case where the frame is attached to the frame 42, and FIG. 43.

Each frame 40, 41, 42, 43 shown in FIG.
FIG. 5 shows a directional characteristic diagram at 195 MHz which is a high band of the VHF band when the film antenna element 2 having a length of 150 mm and a width of 90 mm is attached. FIG. 11A shows a case where the frame is attached to the frame 40, FIG. 10B shows a case where the frame is attached to the frame 41, FIG. 10C shows a case where the frame is attached to the frame 42, and FIG. 43.

Each frame 40, 41, 42, 43 shown in FIG.
FIG. 6 shows a directivity diagram at 620 MHz in the UHF band in a state where the film antenna element 2 having a length of 150 mm and a width of 90 mm is attached. FIG. 11A shows a case where the frame is attached to the frame 40, FIG. 10B shows a case where the frame is attached to the frame 41, FIG. 10C shows a case where the frame is attached to the frame 42, and FIG. 43. 4A to 4D, FIGS. 5A to 5D, and FIGS. 6A to 6D correspond to the front and back directions on the paper surface of FIG.

As is clear from these figures, the directional characteristics are slightly inclined rightward in each figure from the 0-180 degree direction.

Each frame 40, 41, 42, 43 shown in FIG.
FIG. 7 shows the reflection loss in the VHF band (40 MHz to 300 MHz) when the film antenna element 2 having a length of 150 mm and a width of 90 mm is attached. 11A shows the reflection loss of the frame 40, FIG. 10B shows the reflection loss of the frame 41, FIG. 10C shows the reflection loss of the frame 42, and FIG.

Each frame 40, 41, 42, 43 shown in FIG.
FIG. 8 shows the reflection loss in the UHF band (470 MHz to 800 MHz) when the film antenna element 2 having a length of 150 mm and a width of 90 mm is attached. FIG. 11A shows the case where the frame 40 is used, FIG. 10B shows the case where the frame 41 is used, and FIG.
Represents the reflection loss in the case of the frame 43.

As described above, by selecting the frame on which the film antenna element 2 is to be attached, the antenna characteristics can be changed.

FIG. 9 shows a film antenna according to the second embodiment. In this film antenna, film reflecting elements 20a and 20b are provided in addition to the film antenna element 2 of the film antenna of the first embodiment. Other configurations are the same as those of the film antenna of the first embodiment, and therefore, the same parts are denoted by the same reference numerals and description thereof will be omitted.

Like the film antenna element 2, the film reflection elements 20a and 20b are also made of a transparent conductive film and are formed in a rectangular shape longer than the film antenna element 2. For example, the film antenna element 2 has a length dimension 1
50 mm and a width of 90 mm, whereas the film reflecting elements 20 a and 20 b have a length of 300 mm.
, And has a width of 90 mm, which is twice as long as the film antenna element 2. These film reflecting elements 20a, 20b are connected to the horizontal portions 4a, 4b of the frame 4.
Is attached to the window glass 6 at a predetermined interval from the film antenna element 2 so as to be parallel to the film antenna element 2 and sandwich the film antenna element 2 therebetween.

The gain-frequency characteristic when this film antenna is mounted on a frame 41 having both a length dimension and a width dimension of 710 mm is indicated by a symbol A in FIG. For comparison, a symbol B indicates a gain versus frequency characteristic when only the film antenna element 2 is provided in the same frame 41. As is apparent from this figure, when the film reflecting elements 20a and 20b are provided, the gain is improved from the vicinity of 89 MHz in the low band of the VHF band as compared with the case of the film antenna element 2 alone, and particularly, the gain is greatly increased in the UHF band. Is improving. This is because, in addition to the horizontal portions 4a and 4b functioning as a part of the antenna element, the film reflection elements 20a and 20b
This is because, as well as resonating as a part of the antenna element, the film reflecting element reflects the radio wave radiated from the film antenna element.

In the above embodiment, the film antenna element 2 has a rectangular shape, but other shapes, for example, a circular shape or a loop shape may be used. Further, in the above-described embodiment, the film antenna element 2 is attached to the window, but any other material such as a door can be used as long as the support is supported by a conductive frame. . Further, the length dimension and the width dimension of the film antenna 2 are not limited to those described above, but can be variously modified according to the frame used.

[0031]

As described above, according to the film antenna of the present invention, since the frame is used as a part of the antenna element, the size can be reduced and the band can be widened. Further, since the transparent conductive film is used, the appearance is not impaired.

[Brief description of the drawings]

FIG. 1 is a front view of a film antenna according to a first embodiment of the present invention.

FIG. 2 is a front view showing a state where the film antenna of FIG. 1 is attached to various frames.

FIG. 3 is a gain-frequency characteristic diagram in a state where film antennas are mounted on various frames of FIG. 2;

FIG. 4 is a directional characteristic diagram in a low frequency band of a VHF band in a state where film antennas are attached to various frames of FIG. 2;

5 is a directional characteristic diagram in a high frequency range of a VHF band in a state where film antennas are attached to various frames in FIG. 2;

6 is a directional characteristic diagram in a UHF band in a state where film antennas are attached to various frames of FIG. 2;

FIG. 7 is a graph showing reflection loss vs. frequency characteristics in a VHF band in a state where film antennas are attached to various frames in FIG. 2;

8 is a graph showing reflection loss versus frequency characteristics in a UHF band in a state where film antennas are mounted on various frames in FIG. 2;

FIG. 9 is a front view of a second embodiment of the present invention.

10 is a gain-frequency characteristic diagram of the fill antenna of FIG. 9 and the film antenna of FIG. 1;

[Explanation of symbols]

 2 Film antenna 4 Frame 10 Coaxial cable (feeding part) 20a, 20b Reflecting element

Claims (5)

[Claims] 1. A film antenna, comprising: a plate-shaped film antenna element attached to a support supported by a conductive frame; and a power supply unit for supplying power to the film antenna element and the frame. . 2. The film antenna according to claim 1, wherein the film antenna element is formed in a rectangular shape,
The film antenna, wherein the conductive frame has a pair of parallel plate-shaped parallel portions, and the film antenna element is arranged in parallel with the parallel portions. 3. The film antenna according to claim 1, wherein the film antenna element is formed in a rectangular shape,
A film antenna in which a rectangular film reflecting element having a longer dimension than the film antenna element is attached to the support with the film antenna element interposed therebetween in a direction perpendicular to the length direction of the film antenna element. 4. The film antenna according to claim 1, wherein the film antenna element is formed of a transparent conductive film. 5. The film antenna according to claim 3, wherein the film antenna element and the film reflection element are formed of a transparent conductive film.