JPH0623311U - Antenna device - Google Patents

Abstract

(57) [Abstract] [Purpose] The transmission / reception frequency band is expanded, and at the same time, downsizing and low profile of the configuration are realized. [Structure] An antenna device 11 includes a first conductor 12 and a second conductor 13, and one end of the first conductor 12 is connected to a ground conductor 14 and is divided into a plurality of partial conductors 15, 16 and 17. . Lumped constant coils (hereinafter abbreviated as coils) 18 and 19 are interposed between the partial conductors 15, 16 and 17, respectively. A power supply unit 20 is connected to the partial conductor 15. The second conductor 13 has a power feeding portion 21 at one end thereof and a loading coil 22 at the free end portion side. In such an antenna device 11, a radome 23 is provided so as to cover the first conductor 12 and the second conductor 13, and the feeding portions 20 and 21 serve as feeding circuits provided for the partial conductor 15 and the conductor portion 24. Power supply cable 2 provided
5, 26 are connection parts.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an antenna device, and more particularly to a vehicle-mounted antenna device used together with a vehicle-mounted television receiver, which is a transmission line type antenna device capable of transmitting / receiving in a plurality of signal bands.

[0002]

[Prior art]

 Conventionally, as an antenna device used together with an on-vehicle television receiver, a transmission line type antenna called an F-type or inverted F-type antenna installed on the upper surface of a vehicle roof or a rear trunk part has been used. There is. As a conventional example of such a transmission line type antenna, there is JP-A-61-238107. FIG. 8 is a system diagram showing the configuration of the conventional antenna device 1. The antenna device 1 includes a plurality of section conductors 2, 3, and 4, one end of the section conductor 2 is connected to a ground conductor 5, and a lumped constant coil (hereinafter abbreviated as a coil) is provided between the section conductors 2 to 4. ) 6 and 7 are connected respectively. Further, the power feeding portion 8 is connected to the section conductor 2.

The total length L1 of the section conductor 2 is set to a quarter wavelength of the wavelength corresponding to the resonance frequency f1, and the total length L2 including the section conductors 2 and 3 and the coil 6 is set to another predetermined resonance frequency f2. The 1/4 wavelength of the corresponding wavelength is selected, and the total length L3 including the section conductors 2 to 4 and the coils 6 and 7 is selected to the 1/4 wavelength of the wavelength corresponding to another predetermined resonance frequency f3. The antenna device 1 is configured to include the section conductors 2 to 4 and the coils 6 and 7.

Such an antenna device 1 can perform transmission / reception with respect to three types of bands having the resonance frequencies f1 to f3 as center frequencies. As an example of such three types of frequency bands, the frequency band of various television broadcasts in Japan VHF television frequency band 60 to 108 MHz 170 to 222 MHz UHF television frequency band 470 to 770 MHz to set the VHF television. Reception in the frequency band and the UHF television frequency band can be performed.

On the other hand, in order to use such an antenna device 1 as a vehicle-mounted antenna, the section conductors 2 to 4 of the antenna device 1 are set at a height h1 (30 to 40 mm as an example) from the ground conductor 5. ing. Such a setting of the height h1 is performed when a vehicle equipped with such an antenna device 1 is driven into and out of a garage having a ceiling, or when passing under a railway-related elevated facility. The height h1 is set to be as low as possible from the viewpoints such as the height limit to be set and wind noise during running.

[0006]

[Problems to be solved by the device]

 It has been confirmed that when the VHF television frequency band is to be received using the antenna device 1 having the above-described configuration, sufficient reception strength cannot be secured in the high band portion, that is, 170 to 220 MHz reception. That is, according to the experiments by the inventor of the present invention, it is confirmed that the reception characteristic of the antenna device 1 has only an effective band of about 40 MHz from 170 MHz to the high frequency band side, as shown by the line 9 in FIG. ing. Therefore, it has been confirmed that in the vicinity of 222 MHz, which is the upper limit frequency of the VHF television frequency band, reception failure or reception failure occurs.

In order to improve such a situation, a technique of increasing the height h1 from the ground conductor 5 such as the section conductors 2, 3, 4 is considered, but if the height h1 is increased by 10 mm as an example. , Only about 1 MHz band increase is observed. Therefore, in order to obtain an increase of the band of 10 MHz in the antenna device 1, it is necessary to increase the height h1 by about 100 mm, and the total height becomes about 13 to 14 cm, which is mounted on the vehicle and exposed to the outside. No. 1 is extremely defective in view of the factors that determine the height h1 as described above.

An object of the present invention is to solve the above-mentioned technical problems and to provide a small-sized, low-profile antenna device capable of expanding a band capable of transmitting / receiving.

[0009]

[Means for Solving the Problems]

 The present invention is arranged substantially parallel to a ground conductor, has one end connected to the ground conductor, and is divided into a plurality of partial conductors with one or more lumped constant coils interposed therebetween. A first conductor selected such that the distance from the one end is approximately ¼ wavelength of a wavelength corresponding to a plurality of predetermined resonance frequencies; and a ground conductor on the ground conductor side of the first conductor. A second conductor arranged substantially in parallel and supplied from one end with a total length selected to be about ¼ wavelength of a wavelength corresponding to any one of the plurality of resonance frequencies. And the antenna device.

[0010]

[Action]

 An antenna device according to the present invention includes a first conductor and a second conductor, and one end of the first conductor is connected to a ground conductor. The first conductor is divided into a plurality of partial conductors, and lumped constant coils are interposed between the partial conductors. The distance between such a partial conductor and the one end is selected to be about ¼ wavelength of the wavelength corresponding to a plurality of predetermined resonance frequencies. Therefore, the first conductor can perform transmission / reception in a plurality of bands with the plurality of resonance frequencies as the center frequency band.

On the other hand, the second conductor is arranged substantially parallel to the ground conductor on the side closer to the ground conductor than the first conductor, and is fed from one end thereof, and its total length corresponds to any one of the plurality of resonance frequencies. The wavelength is selected to be about 1/4 wavelength. That is, in the plurality of frequency bands in which the first conductor transmits / receives, when the frequency band to be actually transmitted / received deviates from the frequency band in the first conductor, the resonance frequency of the first conductor Bands are chosen to match the offset frequency band.

[0012] This makes it possible to perform transmission / reception in a desired frequency band with the first conductor and the second conductor without changing the shape of the first conductor, for example, by increasing the overall height. Good transmission / reception can be performed in the entire band in which transmission / reception is actually performed in each frequency band. As a result, the band in which transmission / reception is performed can be expanded, and at the same time, the antenna device can be downsized and its posture can be reduced.

[0013]

【Example】

 FIG. 1 is a system diagram showing a basic configuration of an antenna device 11 according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of the antenna device 11. The antenna device 11 includes a first conductor 12 and a second conductor 13, and one end of the first conductor 12 is connected to the ground conductor 14 and a plurality of (for example, three) partial conductors 15, 16, It is divided into 17. Lumped constant coils (hereinafter abbreviated as coils) 18 and 19 are respectively interposed between the partial conductors 15, 16 and 17, and the length L11 of the partial conductor 15 corresponds to a predetermined resonance frequency f 1. The length is selected to correspond to a quarter wavelength of the wavelength.

The total length L12 of the partial conductor 15, the coil 18 and the partial conductor 16 is selected to be about ¼ wavelength of the wavelength corresponding to another predetermined resonance frequency f2, and the partial conductor 15, the coil 18 and the partial conductor The total length L13 of the conductor 16, the coil 19 and the partial conductor 17 is selected to be about ¼ wavelength of the wavelength corresponding to another predetermined resonance frequency f3. A power supply unit 20 is connected to the partial conductor 15. The height h2 of the first conductor 12 from the ground conductor 14 is selected to be about 35 mm, for example.

The second conductor 13 has a power feeding portion 21 at one end thereof, and a loading coil 22 1 at the free end portion side. The total length L14 of the second conductor 22 including the loading coil 22 is selected to be about 1/4 wavelength of the wavelength corresponding to the predetermined resonance frequency f4. Such an antenna device 11 is provided with a redom 23 which covers the first conductor 12 and the second conductor 13, and the feeding parts 20 and 21 are provided with respect to the partial conductor 15 and the conductor part 24. It is a connection portion of the power supply cables 25 and 26 provided in the.

FIG. 3 is a cross-sectional view showing an exploded state of the antenna device 11 of the present embodiment, FIG. 4 is a plan view of the first wiring board 27 on which the above-mentioned first conductor 12 is formed, and FIG. FIG. 6 is a sectional view taken along the section line X5-X5 in FIG. 4, and FIG. 6 is a plan view of a second wiring board 28 on which the second conductor 13 is formed. The antenna device 11 is provided with a base 29 on the surface of which a metal film is formed as a ground conductor 14 by a metal foil or plating made of a synthetic resin material, and on the base 29, a first wiring board is formed as described later. A plurality of support members 30 that support 27 and a plurality of support members 31 that support the second wiring board 28 are provided.

Each of the support members 30 and 31 is composed of shaft portions 32 and 33, and projections 34 and 35 which further protrude from the upper ends of the shaft portions 32 and 33 and have a smaller diameter than the shaft portions 32 and 33. It is formed higher than 33. On the other hand, a plurality of insertion holes 36 through which the shaft portion 32 of the support member 30 is inserted, and the protrusion 35 of the support member 31 are fitted into the second wiring board 28, and the diameter is larger than that of the protrusion 35 and larger than that of the shaft portion 33. A plurality of small-diameter through holes 37 are formed.

That is, with the shaft portion 32 of the support member 30 inserted through the insertion hole 36, the projection 35 of the support member 31 enters into the through hole 37, and the peripheral portion of the through hole 37 at the lower end of FIG. It abuts on the stepped portion between 35 and the shaft portion 33, whereby the second wiring substrate 28 is supported by the support member 31. On the other hand, in the first wiring board 27, a plurality of through holes 38 having a diameter larger than that of the protrusion 34 of the support member 30 and smaller than that of the shaft portion 32 are formed at positions corresponding to the insertion holes 36. On the other hand, the protrusion 34 is formed so as to further protrude toward the radome 23 side than the first wiring board 27 after being inserted through the through hole 38.

The radome 23 is a plate-shaped member made of a synthetic resin material, and a plurality of fitting holes 39 into which the protrusions 34 are fitted are formed on the back surface of the radome 23. On the other hand, the radome 23 includes a plate-shaped covering portion 40 that covers the first wiring board 27, and a side wall 41 that hangs from the peripheral portion of the covering portion 40 toward the first wiring board 27. A plurality of fitting protrusions 43 that fit into the through holes 42 formed in the first wiring board 27 are formed at the free end portion.

That is, with the second wiring board 28 supported by the support member 31 and the first wiring board 27 supported by the support member 30 at a predetermined distance from the second wiring board 28, the radome 23 is The support member 30 supports the first wiring board 27 with a predetermined gap, and the fitting protrusions 43 fit the first wiring board 27.

In the first wiring board 27, as shown in FIG. 5, a partial conductor 16 is formed on a support plate 44 made of a synthetic resin material or the like, as shown in FIGS. 4 and 5. The tip of the partial conductor 16 is connected to the outermost portion of the spiral coil 19 formed on the same surface of the support plate 44, and the innermost portion of the coil 19 is connected through a through hole 45 formed in the support plate 44. The other end of the connecting conductor 46 is connected to the connecting conductor 46 formed on the opposite surface of the supporting plate 44, and the other end of the connecting conductor 46 is also formed on the same side surface of the supporting plate 44 through a through hole 47 formed in the supporting plate 44. It is connected to the formed partial conductor 17. That is, the first wiring board 27 is a so-called double-sided board. Both side surfaces of the support plate 44 are covered with protective films 48 and 49 made of a synthetic resin material.

On the other hand, as shown in FIG. 6, the second wiring board 28 may be a single-sided board, and the conductor portion 24 and the crank-shaped loading coil 22 are formed on the supporting plate 44 similar to the supporting plate 44, and Like the protective films 48 and 49, it is covered with a protective film.

FIG. 7 is a graph showing the operation of the antenna device 11 of this embodiment. The antenna device 11 of the present embodiment is an antenna device for receiving a television signal used in combination with an in-vehicle television receiver, and as described in the section of the prior art, it receives the VHF television frequency. It is intended to go over the entire band. In the present embodiment, the resonance frequencies f1 to f3 of the first conductor 12 are used to enable reception of the VHF frequency band, that is, 90 to 108 MHz (low band) and 170 to 222 MHz (high band), In this respect, the antenna device 1 has the same configuration as that of the conventional antenna device 1 described with reference to FIG.

Therefore, as shown by the line 50 in FIG. 7, only the first conductor 12 has a characteristic that the reception sensitivity is low in the frequency band near 222 MHz in the frequency band of the VHF frequency band (170 to 222 MHz). Therefore, in the vicinity of 222 MHz, reception becomes impossible or reception becomes poor. On the other hand, the signal reception characteristic of the second conductor 13 is shown by line 51 in FIG. That is, the frequency band in which the reception characteristic of the first conductor 12 causes poor reception or the like is to be compensated by the characteristic of the second conductor 13. Therefore, the combined characteristics of the first conductor 12 and the second conductor 13 are as shown by a line 52 in FIG. 7, which enables reception in the entire high band 170 to 222 MHz of the VHF television frequency band. it can.

As described above, in the present embodiment, the first conductor 12 and the second conductor 13 can be used to enable transmission / reception over the entire desired frequency band as described above. . As a result, the frequency band of transmission / reception that can be realized by the antenna device 11 can be expanded, and the height h2 of the first conductor 12 from the ground conductor 14 is too large as described in the section of the prior art. The antenna device 11 having a small size and a low attitude can be realized without increasing the number of antennas.

In the antenna device 11 of the present embodiment, the inverted F-type first conductor 12 and the inverted L-type second conductor 13 are used for the following reason. That is, as described in the section of the prior art, when only the inverted F type antenna device is used, if the frequency band that can be effectively received by the antenna device is narrower than the frequency band of the received signal, it is almost the same shape. Although a technique of adding a reverse inverted F-type antenna device is conceivable, the shape of such an added reverse F-type antenna device is almost the same as the original shape of the reverse F-type antenna device.

On the other hand, when such a pair of inverted F type antenna devices are used together, it is known that if the antenna devices are close to each other, only the operation as a single antenna device is performed. . Therefore, it is necessary to separate the inverted F-type antenna devices from each other. In such a case, when a pair of inverted F-type antenna devices are arranged so as to face each other, that is, when a symmetrical antenna device is added to the antenna device 1 in the conventional example of FIG. In the device, the currents flow in opposite directions and interfere with each other, degrading performance. Therefore, in order to reduce the size of the entire structure, the inverted L-shaped second conductor 13 is added in this embodiment.

Unlike the first conductor 12, the second conductor 13 does not have a short-circuit portion to the ground conductor 14, so that the installation position of the power feeding unit 21 can be appropriately selected, and therefore, the power feeding unit 20. , 21 can be set at almost the same position, and the power feeding cables 25, 26 can be made into a single line. Also in this respect, the configuration can be remarkably simplified.

Further, in the present embodiment, as described above, the effective transmission / reception frequency band of the first conductor 12 and the effective transmission / reception frequency band of the second conductor 13 are different from each other, and therefore both are effective. In addition, a wide receivable frequency band can be realized, and so-called diversity effect can be achieved.

[0030]

[Effect of device]

 As described above, the antenna device according to the present invention includes the first conductor and the second conductor, and one end of the first conductor is connected to the ground conductor. The first conductor is divided into a plurality of partial conductors, and lumped constant coils are interposed between the partial conductors. The distance between such a partial conductor and the one end is selected to be about ¼ wavelength of the wavelength corresponding to a plurality of predetermined resonance frequencies. Therefore, the first conductor can perform transmission / reception in a plurality of bands with the plurality of resonance frequencies as the center frequency band.

On the other hand, the second conductor is arranged substantially parallel to the ground conductor on the side closer to the ground conductor than the first conductor, and is fed from one end thereof, and its total length corresponds to any one of the plurality of resonance frequencies. The wavelength is selected to be about 1/4 wavelength. That is, in the plurality of frequency bands in which the first conductor transmits / receives, when the frequency band to be actually transmitted / received deviates from the frequency band in the first conductor, the resonance frequency of the first conductor Bands are chosen to match the offset frequency band.

With this, it is possible to perform transmission / reception in a desired frequency band with the first conductor and the second conductor without changing the shape of the first conductor, for example, by increasing the total height. Good transmission / reception can be performed in the entire band in which transmission / reception is actually performed in each frequency band. As a result, the band in which transmission / reception is performed can be expanded, and at the same time, the antenna device can be downsized and its posture can be reduced.

[Brief description of drawings]

FIG. 1 is a system diagram showing a basic configuration of an antenna device 11 according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of an antenna device 11.

FIG. 3 is a cross-sectional view showing an exploded state of the antenna device 11 of this embodiment.

FIG. 4 is a plan view of a first wiring board 27.

5 is a cross-sectional view taken along the section line X5-X5 in FIG.

FIG. 6 is a plan view of a second wiring board 28.

FIG. 7 is a graph showing the operation of the antenna device 11 of this embodiment.

FIG. 8 is a system diagram showing a configuration of a conventional antenna device 1.

FIG. 9 is a graph illustrating a problem of a conventional example.

[Explanation of symbols]

 11 Antenna Device 12 First Conductor 13 Second Conductor 14 Grounding Conductor 15-17 Partial Conductor 18,19 Coil 20,21 Feeding Part 22 Loading Coil

Claims (1)

[Scope of utility model registration request] 1. Arranged substantially parallel to the ground conductor,
One end is connected to a ground conductor and is divided into a plurality of partial conductors with one or more lumped constant coils interposed, and the distance between each partial conductor and the one end corresponds to a plurality of predetermined resonance frequencies. The first conductor selected to have a length of about 1/4 wavelength of the wavelength to be set, and is arranged substantially parallel to the ground conductor on the side of the ground conductor with respect to the first conductor and is fed from one end and has a total length of the plurality of A second conductor selected to have a length of about ¼ wavelength of a wavelength corresponding to any one of the resonance frequencies of 1.