JP2005160050A - Patch antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure antenna directivity at a low elevation angle. <P>SOLUTION: In a patch antenna (10) including a dielectric (12) having a top surface (12u), a bottom surface (12d) and a side surface (12s), a radiation element (14) formed on the top surface (12u) of the dielectric, and a ground conductor (16) formed on the bottom surface (12d) of the dielectric, a ring-shaped non-feeding element (18) is formed on the side surface (12s) of the dielectric. The non-feeding element (18) preferably may be formed on the side surface of the dielectric in the vicinity of the top surface of the dielectric. In addition, the non-feeding element (18) may be formed by pasting a copper tape or by thick film printing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a patch antenna, and in particular, receives digital radio broadcasts by receiving radio waves from artificial satellites (hereinafter also referred to as “satellite waves”) or radio waves on the ground (hereinafter also referred to as “terrestrial waves”). It relates to a patch antenna that can be used as an antenna for a digital radio receiver.

  Recently, a digital radio receiver that can receive a digital radio broadcast by receiving a satellite wave or a ground wave has been developed and put into practical use in the United States. This digital radio receiver is mounted on a mobile station 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.

  As described above, since radio waves having a frequency of about 2.3 GHz band are used in digital radio broadcasting, an antenna for receiving the radio waves must be installed outdoors. Therefore, when a digital radio receiver is mounted on a vehicle, the antenna must be attached to the roof of the vehicle.

  This type of antenna needs to have a wide directivity. This is because the digital receiver needs to receive a satellite wave coming from a relatively low elevation satellite having an elevation angle in the range of 20 ° to 60 °. This is also because the elevation angle of the ground wave is substantially 0 °.

  In general, a planar (planar) antenna such as a patch antenna has a narrow directivity, and thus has been considered unsuitable for this type of antenna. However, even if it is a patch antenna, it is known that antenna directivity spreads by using a ground board (earth board) with a large area (for example, refer patent document 1).

  In particular, when a digital radio receiver is mounted on an automobile, the antenna is attached to the roof of the automobile as described above. In this case, since the roof of the automobile itself works as a ground plate, it has been confirmed that even a patch antenna can be sufficiently used as an antenna for a digital radio receiver.

  On the other hand, there is a demand for listening to digital radio broadcasts not only from the inside of a car but also from a portable acoustic electronic device such as a CD radio cassette player. In order to respond to this requirement, it has been proposed to install a patch antenna in a door-type lid that is provided on the top surface of the case of a portable acoustoelectronic device and that can be opened and closed for attaching and detaching an optical disk. . In this case, it is necessary to provide a ground plate (ground plate) under the patch antenna.

  One type of planar antenna is a microstrip antenna. As this microstrip antenna, one in which a parasitic element is provided on the edge of the top surface of the ground plane is known (for example, see Patent Document 2).

  A small planar patch antenna used for a global positioning system (GPS) is also known (see, for example, Patent Document 3).

JP 2003-163521 A JP-A-11-284429 JP-A-7-94934

  As described above, in the patch antenna, it is necessary to use a ground plate having a large area in order to obtain antenna directivity at a low elevation angle. However, if only the ground plate is provided, the antenna directivity of the patch antenna is uniquely determined depending on the size thereof, and it is difficult to obtain the antenna directivity at a low elevation angle beyond that.

  On the other hand, in Patent Document 2, a parasitic element is provided on the top surface of the ground plane, which is intended to prevent diffracted waves from the end of the ground conductor. Even the device described in Patent Document 2 can improve the antenna characteristics. However, in a structure in which a parasitic element is provided on the top surface, interference with the radiating element is increased. Further, since adjustment in the height direction is impossible, there may be a case where desired antenna characteristics cannot be satisfied.

  Therefore, the subject of this invention is providing the patch antenna which can ensure the antenna directivity in a low elevation angle.

  Another object of the present invention is to provide a patch antenna that can reduce interference with a radiating element.

  Still another object of the present invention is to provide a patch antenna that can be easily adjusted in the height direction.

  Still another object of the present invention is to provide a patch antenna that can secure the area of the dielectric on the top surface without increasing the size of the antenna itself.

  According to the present invention, the dielectric (12) having the top surface (12u), the bottom surface (12d), and the side surface (12s), the radiating element (14) formed on the top surface of the dielectric, the dielectric A patch antenna (10) having a grounding conductor (16) formed on the bottom surface of the antenna, and having a ring-shaped parasitic element (18) formed on a side surface of the dielectric An antenna is obtained.

  In the patch antenna according to the present invention, the parasitic element is preferably formed at the uppermost stage on the side surface of the dielectric. Further, the parasitic element may be formed by attaching a copper tape, or may be formed by thick film printing.

  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 ring-shaped parasitic element is provided on the side surface of the dielectric, the antenna directivity at a low elevation angle can be ensured.

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

  A patch antenna 10 according to an embodiment of the present invention will be described with reference to FIG. 1, (a) is a perspective view of the patch antenna 10, (b) is a plan view of the patch antenna 10, (c) is a front view of the patch antenna 10, (d) is a left side view of the patch antenna 10, e) is a right side view of the patch antenna 10, FIG. 5F is a rear view of the patch antenna 10, and FIG.

  The patch antenna 10 has a substantially rectangular parallelepiped dielectric 12. In the illustrated example, the dielectric 12 has a length (length) × width (width) × height of 20 mm × 20 mm × 4 mm. The dielectric 12 is made of a ceramic material or resin. The dielectric 12 has a top surface 12u, a bottom surface 12d, and a side surface 12s. Actually, as shown in FIG. 1, the corners of the side surface 12s of the dielectric 12 are chamfered.

  A radiating element 14 is formed on the top surface 12 u of the dielectric 12. A ground conductor 16 is formed on the bottom surface 12 d of the dielectric 12. Reference numeral 15 denotes a feeding point.

  A ring-shaped parasitic element 18 is formed on the side surface 12 s of the dielectric 12. In the illustrated example, the parasitic element 18 is formed on the uppermost stage of the side surface 12 s of the dielectric 12. In the illustrated example, the parasitic element 18 is formed by attaching a copper tape. The width of the copper tape is 1 mm. Instead of this, the parasitic element 18 may be formed by thick film printing.

  FIG. 2 shows the antenna radiation characteristic of the patch antenna 10 having the ring-shaped parasitic element 18 shown in FIG. 1, and FIG. 3 shows the antenna radiation characteristic of a conventional patch antenna without the ring-shaped parasitic element. 2 and 3 show the antenna radiation characteristics when the patch antenna is placed in the center of a 4 foot (about 120 cm) square ground plate. Each of FIGS. 2 and 3 shows a gain characteristic in the circumferential direction when the elevation angle is 20 °, 30 °, 40 °, 50 °, and 60 °.

  2 and 3 that the patch antenna 10 of the present invention has a larger gain than the conventional patch antenna. Specifically, when the elevation angle is 30 °, the average gain of the patch antenna 10 of the present invention is 2.10 [dB] larger than that of the conventional patch antenna.

  Thus, in the present invention, since the parasitic element 18 is provided on the side surface 12s instead of the top surface 12u, interference with the radiating element 14 can be reduced. Further, by adjusting the width and position of the parasitic element 18 in the height direction, the antenna characteristics at a low elevation angle can be easily adjusted. Furthermore, since the area of the dielectric 12 on the top surface 12u does not change, it is not necessary to increase the size of the antenna.

  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.

The structure of the patch antenna which concerns on one embodiment of this invention is shown, (a) is a perspective view, (b) is a top view, (c) is a front view, (d) is a left view, (e) is a right side (F) is a rear view, and (g) is a bottom view. It is a figure which shows the antenna radiation | emission characteristic at the time of mounting the patch antenna shown in FIG. 1 in the center of a 4-foot square ground board. It is a figure which shows the antenna radiation | emission characteristic at the time of mounting the conventional patch antenna on the center of a 4-foot square ground board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Patch antenna 12 Dielectric body 12u Top surface 12d Bottom surface 12s Side surface 14 Radiation element 16 Ground conductor 18 Parasitic element

Claims (4)

  A patch antenna comprising: a dielectric having a top surface, a bottom surface, and side surfaces; a radiating element formed on the top surface of the dielectric; and a ground conductor formed on the bottom surface of the dielectric. A patch antenna comprising a ring-shaped parasitic element formed on the side surface of the dielectric.   The patch antenna according to claim 1, wherein the parasitic element is formed on an uppermost stage of the side surface of the dielectric.   The patch antenna according to claim 1 or 2, wherein the parasitic element is formed by attaching a copper tape. The patch antenna according to claim 1 or 2, wherein the parasitic element is formed by thick film printing.

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