JP4569760B2 - Antenna device - Google Patents

Description

The present invention relates to an antenna device having an antenna unit , and in particular, receives a radio wave from an artificial satellite (hereinafter also referred to as “satellite wave”) or a radio wave on the ground (hereinafter also referred to as “terrestrial wave”), and digital radio. The present invention relates to an antenna device having an antenna unit for a digital radio receiver capable of listening to broadcasting.

  Recently, a digital radio receiver that can receive a digital radio broadcast by receiving satellite waves or terrestrial waves has been developed and put into practical use in the United States. That is, two broadcast stations, XM and Sirius, provide radio programs with a total of 250 channels or more nationwide. This digital radio receiver is generally mounted on a moving body such as an automobile, and can receive radio waves by receiving radio waves having a frequency of about 2.3 GHz. That is, the digital radio receiver is a radio receiver capable of listening to mobile broadcasts. Since the frequency of the received radio wave is about 2.3 GHz, the reception wavelength (resonance wavelength) λ at that time is about 128.3 mm. The terrestrial wave is a satellite wave that is once received by the earth station, then slightly shifted in frequency, and retransmitted with linearly polarized waves. That is, satellite waves are circularly polarized while terrestrial waves are linearly polarized.

  The antenna device for XM satellite radio receives circularly polarized radio waves from two geostationary satellites, and receives radio waves from the ground linear polarization equipment in the dead zone. On the other hand, the antenna device for Sirius satellite radio receives circularly polarized radio waves from three orbiting satellites (synchronous type), and receives radio waves by the ground linear polarization equipment in the dead zone.

  As described above, since radio waves with a frequency of about 2.3 GHz band are used in digital radio broadcasting, an antenna device that receives the radio waves must be installed outdoors. Therefore, when the digital radio receiver is mounted on a moving body such as an automobile, the antenna device must be attached to the roof of the moving body.

  Such an antenna device includes an antenna unit and an antenna case for covering the antenna unit. The antenna case includes a dome-shaped top cover and a bottom plate. The antenna unit includes an antenna element, a circuit board, and a shield case. The antenna element is composed of, for example, a ceramic patch antenna and receives satellite waves. On the circuit board, a circuit (hereinafter referred to as a signal processing circuit) for performing various signal processing such as signal amplification on the signal received by the antenna element is formed. The shield case is for shielding the signal processing circuit.

  A conventional ceramic patch antenna used as an antenna element is obtained by performing screen printing on both surfaces of a dielectric made of a ceramic material.

  Conventional ceramic patch antennas have antenna characteristics with a large antenna directivity gain at a low elevation angle. However, in an antenna device for Sirius satellite radio, an antenna element having an antenna characteristic with a large directivity gain at a high elevation angle is desired.

Accordingly, an object of the present invention is to provide an antenna apparatus having an antenna unit including a patch antenna having an antenna characteristic with a high antenna directivity gain at a high elevation angle.

According to the onset bright, the patch antenna (20), attached to the bottom surface of the patch antenna, the circuit board signal processing circuit is formed (22), a shield case for shielding the signal processing circuit (24) , in the antenna device (10) having an antenna unit (12) provided with said antenna unit (12) has said patch antenna (20) of the provided on the top surface was waveguide (40) The antenna device (10) includes a bottom plate (14) and a unit fixing member (30) disposed between the antenna unit and the bottom plate, and the unit fixing member includes the antenna unit. Is fixed on the bottom plate, an antenna device is obtained.

In the antenna device according to the present invention, the director (40) includes a cushion member (41) attached to the top surface of the patch antenna, and a metal ring (42) installed on the cushion member. It is preferable that it is comprised from these. Such an antenna device is used, for example, as a satellite radio reception antenna device . The bottom plate (14) includes a plurality of bosses (142) having screw holes (142a) into which a plurality of screws (26) are screwed, and the unit fixing member (30) includes the plurality of bosses (142). The antenna unit has a plurality of boss receiving portions (31) provided at positions corresponding to the bosses, and the plurality of boss receiving portions have communication holes (31a) communicating the plurality of screws. (12) may include an ear (241) having a through hole (24b) penetrating at least two of the plurality of screws. The unit fixing member (30) has a pair of downwardly extending claws (32) for temporarily fixing the antenna device (10) to the moving body, and the bottom plate (14) It is desirable to have two holes (141b) through which the claws pass.

  In addition, the code | symbol in the said parenthesis is attached | subjected in order to make an understanding of this invention easy, and it is only an example, and of course is not limited to these.

  In the present invention, since the director is provided on the top surface of the patch antenna, the directivity gain at a high elevation angle can be increased.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  An antenna apparatus 10 including a patch antenna according to an embodiment of the present invention will be described with reference to FIG. The illustrated antenna device 10 is an antenna device for a digital radio receiver, and is used by being installed on the roof of a moving body such as an automobile.

  The illustrated antenna device 10 includes an antenna unit 12 and an antenna case (described later) for covering the antenna unit 12. The antenna case includes a dome-shaped top cover (not shown) and a bottom plate 14. The antenna unit 12 is housed in the top cover.

  The antenna unit 12 includes an antenna element 20, a circuit board 22, and a shield case 24. The illustrated antenna element 20 is composed of a ceramic patch antenna and receives satellite waves. The circuit board 22 is formed with a circuit (hereinafter referred to as a signal processing circuit) that performs various signal processing such as signal amplification on the signal received by the antenna element 20. The antenna element 20 and the circuit board 22 are joined by a double-sided tape or the like (not shown).

  Connected to the circuit board 22 is a cable (not shown) for taking a received signal out of the antenna case. A shield case 24 for shielding the signal processing circuit is attached to the main surface of the circuit board 22 opposite to the side where the antenna element 20 is disposed.

  The shield case 24 has an opening 24a for passing a cable. The shield case 24 has a pair of ears 241 extending outward from both side surfaces. These ears 241 have through holes 24 b for passing through the screws 26.

  The antenna device 10 includes a unit fixing member 30 disposed between the antenna unit 12 and the bottom plate 14. As will be described later, the unit fixing member 30 is for temporarily fixing the antenna device 10 to the roof of the moving body (vehicle body) and fixing the antenna unit 12 on the bottom plate 14. That is, the unit fixing member 30 is disposed directly below the antenna unit 12.

  On the other hand, the bottom plate 14 has a recess 141 for accommodating the unit fixing member 30. The bottom plate 14 has three bosses 142 in which screw holes 142a into which the three screws 26 are screwed are cut. Two of these three bosses 142 are provided at positions corresponding to the pair of ears 241 of the shield case 24.

  The unit fixing member 30 has three boss receiving portions 31 that receive the bosses at positions corresponding to the three bosses 142 of the bottom plate 14. These boss receiving portions 31 are provided with communication holes 31 a for communicating the three screws 26. The unit fixing member 30 has a hole 30a for passing a cable. Further, the unit fixing member 30 has a pair of claws 32 extending downward to temporarily fix the antenna device 10 to the roof of the moving body (vehicle body).

  The bottom plate 14 has a hole 141 a for passing the cable through the recess 141 and two holes 141 b for passing the pair of claws 32.

  Hereinafter, a method for fixing the antenna device 10 having such a configuration to a moving body (vehicle body) will be described with reference to FIG.

  First, the pair of claws 32 of the unit fixing member 30 are passed through the two holes 141 b of the bottom plate 14. At this time, the three bosses 142 of the bottom plate 14 are received while being inserted into the boss receiving portions 31 of the unit fixing member 30.

  Next, the three screws 26 are screwed into the screw holes 142 a of the boss 142 through the two through holes 24 b of the shield case 24 and the three communication holes 31 a of the unit fixing member 30. As a result, the antenna unit 12 is fixed on the bottom plate 14 via the unit fixing member 30.

  Next, a cylindrical bolt 50 extending downward from the bottom surface of the bottom plate 14 is passed through an opening (not shown) formed in the roof (not shown) of the moving body (vehicle body). Thereby, the antenna apparatus 10 is temporarily fixed on the roof of a moving body (vehicle body).

  And this antenna apparatus 10 is permanently fixed on the roof of a mobile body (vehicle body) by screwing a nut (not shown) with the volt | bolt 50. As shown in FIG.

  As described above, in the present embodiment, the unit fixing member 30 for temporarily fixing the antenna device 10 on the moving body (vehicle body) and fixing the antenna unit 12 on the bottom plate 14 is directly below the antenna unit 12. The unit fixing member 30 is arranged so as to overlap the antenna unit 12. As a result, the space required in the antenna case can be reduced. Therefore, it is possible to provide the antenna device 10 that is smaller and has high design.

  The patch antenna 20 made of ceramic is obtained by performing screen printing on both surfaces (top and bottom surfaces) of a dielectric made of a ceramic material. More specifically, the patch antenna 20 has a configuration in which a radiating element (not shown) is formed on the top surface of a dielectric, and a ground conductor (not shown) is formed on the bottom surface.

  The patch antenna 20 according to the present embodiment has a director 40 mounted on the top surface thereof. The director 40 includes a foam cushion member 41 and a rectangular metal ring 42. The cushion member 41 is made of, for example, a polyurethane foam, and is preferably made of a material having a dielectric constant as low as possible. The cushion member 41 is affixed to the top surface of the patch antenna 20. The metal ring 42 is made of a metal material such as aluminum or copper. The metal ring 42 is installed on the cushion member 41. In the illustrated embodiment, the metal ring 42 is formed of a metal tape.

  Since the director 40 is composed of the cushion member 41 and the rectangular metal ring 42, it has a very inexpensive and simple structure.

  FIG. 2 shows antenna directivity gains of a conventional patch antenna (20) including only the patch antenna 20 and a patch antenna (20, 40) of the present invention including a combination of the patch antenna 20 and the director 40. In FIG. 2, the thick line shows the antenna directivity gain of the patch antenna of the present invention, and the thin line shows the antenna directivity gain of the conventional patch antenna. As is apparent from FIG. 2, the patch antennas (20, 40) of the present invention have a higher antenna directivity gain at a high elevation angle than the conventional patch antenna (20).

  Thus, by attaching the director 40 to the top surface of the patch antenna 20, the antenna directivity can be adjusted.

  Although the present invention has been described above with reference to preferred embodiments, it is needless to say that the present invention is not limited to the above-described embodiments. For example, in the above-described embodiment, a waveguide composed of a combination of a cushion member and a metal ring is used, but any configuration may be used as long as the antenna directivity can be adjusted. Further, the metal ring is not limited to a rectangle, and various shapes may be employed. The dielectric constituting the patch antenna is not limited to ceramic, and a resin or the like may be used. A cushion member is not limited to a foaming thing, What is necessary is just a dielectric constant as small as possible. The metal ring is not limited to a metal tape.

  The antenna device described in the above embodiment is suitable for an antenna device for a digital radio receiver. However, the antenna device is not limited to this, and an antenna device for a GPS receiver, other satellite waves, It can also be applied as an antenna device for mobile communication for receiving terrestrial waves.

It is a disassembled perspective view which shows the antenna apparatus containing the patch antenna which concerns on one embodiment of this invention. It is a figure which shows the antenna directivity gain characteristic of the conventional patch antenna and the patch antenna shown in FIG.

Explanation of symbols

10 antenna device 12 antenna unit 20 antenna element (patch antenna)
22 Circuit board 24 Shield case 40 Waveguide 41 Cushion member 42 Metal ring

Claims (5)

In an antenna apparatus having an antenna unit comprising: a patch antenna; a circuit board attached to the bottom surface of the patch antenna; and a signal processing circuit formed thereon; and a shield case that shields the signal processing circuit.
The antenna unit has a director provided on the top surface of the patch antenna ,
The antenna device has a bottom plate, and a unit fixing member disposed between the antenna unit and the bottom plate,
The antenna device, wherein the unit fixing member fixes the antenna unit on the bottom plate . The antenna device according to claim 1 , wherein the director includes a cushion member attached to the top surface of the patch antenna, and a metal ring installed on the cushion member. The antenna device is a satellite radio receiving antenna device, an antenna device according to claim 1 or 2. The bottom plate has a plurality of bosses in which screw holes into which a plurality of screws are screwed are cut, and the unit fixing member is provided at a position corresponding to the plurality of bosses and has a plurality of boss receiving portions. The plurality of boss receiving portions are provided with communication holes for communicating the plurality of screws, and the antenna unit has a through hole that penetrates at least two of the plurality of screws. The antenna device according to claim 1, wherein the antenna device has an empty ear. 2. The unit fixing member has a pair of downwardly extending claws that temporarily fix the antenna device to the moving body, and the bottom plate has two holes through which the pair of claws are passed. 5. The antenna device according to any one of 1 to 4.

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