JP4223174B2 - Film antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a film antenna, and more particularly to a film antenna that is attached to a conductive frame such as a window frame.
[0002]
[Prior art]
A film antenna is an antenna element formed using a conductive film, and may be used by being attached to, for example, a window glass. Some film antennas are conventionally configured as dipole antennas having a length that resonates with the reception center frequency.
[0003]
[Problems to be solved by the invention]
When a VHF band antenna is constituted by such a dipole film antenna, for example, it is necessary to set the length of the element of the film antenna so as to resonate at the reception center frequency of the VHF band. This length was relatively long, and it was difficult to affix it to window glass or the like. In addition, when a shared antenna capable of receiving not only in the VHF band but also in the UHF band is configured by a film antenna, the pattern becomes complicated, and it takes time and effort to create it.
[0004]
An object of the present invention is to provide a film antenna that can receive radio waves in a desired frequency band and has a simple configuration even when the length dimension is short.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has a pair of horizontal portions that are spaced apart from each other, and a pair of vertical portions that connect both ends of the pair of horizontal portions, respectively. Are affixed in parallel with the pair of horizontal portions to a support supported by a selected one of a plurality of different conductive frames, and the length is short for receiving radio waves to be received. A rectangular film antenna element, a filter antenna element, and a power feeding unit that feeds power to one of the pair of vertical parts are provided.
[0006]
In this film antenna, a pair of horizontal portions parallel to the rectangular film antenna element 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 horizontal portion of the frame to which the film antenna element is attached. Moreover, since the film antenna element has a rectangular shape, its manufacture is easy.
[0007]
The film antenna element may have a length dimension of 100 to 200 mm and a distance between the film antenna element and the one vertical portion of about 30 mm. In addition, the power feeding unit can feed power to the film antenna element at an end portion close to the one vertical portion of the film antenna element.
[0009]
In addition, two rectangular film reflecting elements having a length longer than that of the film antenna element can be attached to the support in parallel with the pair of horizontal portions with the film antenna element interposed therebetween. .
[0010]
When configured in this way, the antenna characteristics near the frequency band that resonates with the length of the film reflecting element can be improved, and the reflecting element is in the form of a film. Absent.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The film antenna of the 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 affixed to a support, for example, glass 6 supported by a frame 4. Since it is made of a transparent conductive film, even if the film antenna element 2 is attached to the glass 6, it does not stand out and the aesthetic appearance is not impaired.
[0013]
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 in parallel with each other and spaced apart from each other, and further, the first parallel portion 4a, It also has second parallel parts, for example, vertical parts 4c and 4d, which are perpendicular to 4b and are spaced in parallel to each other. A rectangular glass 6 is supported in a space surrounded by the horizontal portions 4a and 4b and the vertical portions 4c and 4d. These horizontal portions 4a and 4b and vertical portions 4c and 4d have conductivity, and the surface may be painted.
[0014]
The film antenna element 2 is affixed in parallel with the horizontal portions 4a and 4b and substantially at the center of the vertical portions 4c and 4d. The film antenna element 2 is for receiving television broadcast radio waves in a plurality of frequency bands, for example, UHF band and VHF band, and the length dimension is, for example, 100 to 200 mm, and the width dimension is, for example, 80 to 100 mm. It is arranged at a position about 30 mm away from the vertical portion 4c. This length dimension is considerably short when considered for reception in the VHF band.
[0015]
A copper foil portion 8 for feeding is attached to a position near the vertical portion 4 c in the film antenna element 2. The copper foil portion 8 is connected to a power feeding portion, for example, a core wire 12 of the coaxial cable 10. In addition, the outer conductor 14 of the coaxial cable 10 serving as a power feeding portion is connected to a window key 16 provided in the vertical portion 4c. The key 16 also has conductivity, and is mechanically fixed to the vertical portion 4c by a fixing portion 16a. The outer conductor 14 is coupled to the fixed portion 16a. When the fixed portion 16a is not coated, the external conductor 14 is directly screwed to the fixed portion 16 for connection. When the fixed portion 16a is painted, it is indirectly coupled. For example, electrostatic coupling is performed.
[0016]
Since the frame body 4 is connected to the external conductor 14 in this way, the frame body 4 functions as an antenna element. In particular, since the horizontal portions 4a and 4b are arranged in parallel with the film antenna element 2, it is considered that these portions function as antenna elements.
[0017]
As the frame body 4, various sizes can be used. For example, as shown in FIG. 2A, a frame 40 having a length dimension of 850 mm and a height dimension of 300 mm, a frame body 41 having a length dimension and a height dimension of 710 mm as shown in FIG. As shown in the figure (c), a frame body 42 having a length dimension of 900 mm and a height dimension of 820 mm is used, and a frame body 43 having a length dimension and a height dimension of 1030 mm as shown in the figure (d). can do.
[0018]
The gain vs frequency characteristics in the state where the film antenna element 2 having a length dimension of 150 mm and a width dimension of 90 mm is attached to these frames 40, 41, 42, 43 are shown in FIG. Indicated by d. This is a case where the symbol a uses the frame body 40, the symbol b uses the frame body 41, the symbol c uses the frame body 42, and the symbol d uses the frame body 43. As is apparent from FIG. 3, in any 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.
[0019]
Further, when the lengths of the horizontal portions 4a and 4b, that is, the lengths of the frames 40 to 43 are different, the gain-frequency characteristics are different. In particular, when the frame body 42 is used, the gain is greatly improved in the low range (76 MHz to 108 MHz) of the VHF band, and when the frame body 40 is used, the gain is greatly improved in the UHF band (470 MHz to 770 MHz).
[0020]
Further, each frame 40, 41, 42, 43 shown in FIG. 2 is oriented at 90 MHz, which is the low frequency band of the VHF band in a state in which the film antenna element 2 having a length dimension of 150 mm and a width dimension of 90 mm is attached. A characteristic diagram is shown in FIG. When (a) is attached to the frame body 40, (b) is attached to the frame body 41, (c) is attached to the frame body 42, (d) is the frame body. 43 is attached.
[0021]
Directional characteristic diagram at 195 MHz, which is the high band of the VHF band, with the film antenna element 2 having a length dimension of 150 mm and a width dimension of 90 mm attached to each frame body 40, 41, 42, 43 shown in FIG. Is shown in FIG. When (a) is attached to the frame body 40, (b) is attached to the frame body 41, (c) is attached to the frame body 42, (d) is the frame body. 43 is attached.
[0022]
FIG. 6 shows a directional characteristic diagram at 620 MHz in the UHF band in a state where the film antenna element 2 having a length dimension of 150 mm and a width dimension of 90 mm is attached to each of the frames 40, 41, 42, and 43 shown in FIG. Show. When (a) is attached to the frame body 40, (b) is attached to the frame body 41, (c) is attached to the frame body 42, (d) is the frame body. 43 is attached. 4 (a) to (d), FIGS. 5 (a) to (d), and FIGS. 6 (a) to 6 (d), the 0 ° -180 ° direction is the front and back direction of the paper surface in FIG.
[0023]
As is clear from these figures, the directivity is slightly inclined from the 0-180 degree direction to the right in each figure.
[0024]
The reflection loss in the VHF band (40 MHz to 300 MHz) when the film antenna element 2 having a length dimension of 150 mm and a width dimension of 90 mm is attached to each of the frames 40, 41, 42, and 43 shown in FIG. 7 shows. 4A shows the reflection loss in the case of the frame body 40, FIG. 2B shows the frame body 41, FIG. 4C shows the frame body 42, and FIG.
[0025]
The reflection loss in the UHF band (470 MHz to 800 MHz) in a state where the film antenna element 2 having a length dimension of 150 mm and a width dimension of 90 mm is attached to each of the frames 40, 41, 42, and 43 shown in FIG. It is shown in FIG. When the figure (a) is the frame 40, the figure (b) is the frame 41, the figure (c) is the frame 42, the reflection loss when the figure (d) is the frame 43. It is.
[0026]
Thus, the antenna characteristics can be changed by selecting a frame body to which the film antenna element 2 is attached.
[0027]
FIG. 9 shows a film antenna according to the second embodiment. In this film antenna, film reflection elements 20a and 20b are provided in addition to the film antenna element 2 of the film antenna of the first embodiment. Since other configurations are the same as those of the film antenna of the first embodiment, the same parts are denoted by the same reference numerals and description thereof is omitted.
[0028]
Similarly to the film antenna element 2, the film reflection elements 20 a and 20 b 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 of 150 mm and a width dimension of 90 mm, whereas the film reflection elements 20a and 20b have a length dimension of 300 mm and a width dimension of 90 mm. It has a length twice that of the element 2. These film reflecting elements 20a and 20b are parallel to the horizontal portions 4a and 4b of the frame 4 and are spaced from the film antenna element 2 by a predetermined distance so as to sandwich the film antenna element 2 therebetween. It is pasted.
[0029]
A gain vs. frequency characteristic when this film antenna is attached to 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, the gain vs. frequency characteristic when only the film antenna element 2 is provided in the same frame 41 is indicated by a symbol B. As is apparent from this figure, when the film reflecting elements 20a and 20b are provided, the gain is improved from around 89 MHz in the low frequency band of the VHF band as compared with the case of the film antenna element 2 alone, and particularly in the UHF band, the gain is greatly increased. Has improved. This is because the horizontal portions 4a and 4b function as a part of the antenna element, and the film reflection elements 20a and 20b also resonate as a part of the antenna element and are radiated from the film antenna element. This is because the reflected film wave is reflected by the film reflecting element.
[0030]
In the above embodiment, the film antenna element 2 has a rectangular shape, but other shapes such as a circular shape or a loop shape can also be used. In the above embodiment, the film antenna element 2 is attached to the window. However, as long as the support is supported by the conductive frame, other things such as a door can be used. . Moreover, the length dimension and width dimension of the film antenna 2 are not restricted to what was mentioned above, According to the frame used, various deformation | transformation are possible.
[0031]
【The invention's effect】
As described above, according to the film antenna according to the present invention, since the frame is used as a part of the antenna element, it is possible to reduce the size and widen the band .
[Brief description of the drawings]
FIG. 1 is a front view of a film antenna according to a first embodiment of the present invention.
2 is a front view of a state in which the film antenna of FIG. 1 is attached to various frames. FIG.
3 is a gain vs. frequency characteristic diagram in a state where film antennas are attached to the various frames shown in FIG. 2. FIG.
4 is a directional characteristic diagram in the low frequency range of the VHF band in a state where film antennas are attached to the various frames of FIG.
5 is a directional characteristic diagram in the high frequency region of the VHF band in a state where film antennas are attached to the various frames of FIG. 2;
6 is a directional characteristic diagram in the UHF band in a state where film antennas are attached to the various frames shown in FIG. 2;
7 is a graph showing reflection loss versus frequency characteristics in the VHF band in a state where film antennas are attached to the various frames shown in FIG. 2;
8 is a graph showing reflection loss vs. frequency characteristics in the UHF band in a state where film antennas are attached to the various frames shown in FIG.
FIG. 9 is a front view of a second embodiment of the present invention.
10 is a gain versus frequency characteristic diagram of the fill antenna of FIG. 9 and the film antenna of FIG.
[Explanation of symbols]
2 Film antenna 4 Frame 10 Coaxial cable (feeding part)
20a, 20b Reflective element

Claims (4)

Select from among a plurality of conductive frames having a pair of horizontal portions that are spaced apart and a pair of vertical portions that connect both ends of the pair of horizontal portions, each having a different size. A rectangular film antenna element that is affixed to a support that is supported in parallel with the pair of horizontal portions and that is short for receiving radio waves that are about to be received;
A power feeding unit that feeds power to the filter antenna element and one of the pair of vertical parts,
A film antenna. 2. The film antenna according to claim 1, wherein the length of the film antenna element is 100 to 200 mm, and the distance between the film antenna element and the one vertical portion is about 30 mm . The film antenna according to claim 1, wherein the power feeding unit feeds power to the film antenna element at an end portion close to the one vertical portion of the film antenna element . 2. The film antenna according to claim 1, wherein two rectangular film reflecting elements having a length dimension longer than that of the film antenna element are sandwiched between the film antenna elements, and are parallel to the pair of horizontal portions. A film antenna attached to the body .

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