JP2005136562A - Circular polarized wave antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circular polarized wave antenna which has a simple configuration and is easily manufactured. <P>SOLUTION: Four antenna elements 6 each having an L shape are disposed at an interval of about 90° on the one main surface 2a of a substrate 2. Each of the antenna elements 6 is provided with a perpendicular portion 6b approximately perpendicular to the main surface 2a, and a horizontal portion 6a extending almost parallel to the main surface 2a to the end of this perpendicular portion 6b. A power feeding circuit 8 is directly connected to each of the perpendicular portions 6b to feed power to each of the antenna elements 6 with phase difference of 90°. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a circularly polarized antenna.

  Digital radio broadcasting is being planned to transmit the same program from satellites and ground stations using signals with the same frequency and different polarizations. In order to receive this broadcast, at least a circularly polarized antenna that receives circularly polarized radio waves from an artificial satellite is required. An example of this circularly polarized antenna is disclosed in Patent Document 1.

  In the technique of Patent Document 1, a loop antenna portion is formed along a peripheral surface of a cylindrical body obtained by rounding a flexible insulating film member around a central axis into a cylindrical shape. The loop antenna portion is provided with electromagnetic coupling lines perpendicular to the loop portions at intervals of 90 degrees. Four feed lines that are electromagnetically coupled by arranging the electromagnetic coupling lines in parallel with a gap are provided.

JP 2003-174314 A

  In the technique of Patent Document 1, the electromagnetic coupling line and the feed line are electromagnetically coupled in order to improve the point that the impedance increases when the loop antenna unit is directly fed. However, for this reason, not only the feeder line but also the electromagnetic coupling line has to be formed, and the configuration is complicated.

  An object of the present invention is to provide a circularly polarized antenna having a simple configuration.

  The circularly polarized antenna of the present invention has a substrate. This substrate can be disposed above a reference potential portion that functions as a reflector at a predetermined distance. This substrate has two main surfaces facing each other. Four antenna elements are arranged at intervals of approximately 90 degrees on one main surface of the substrate. For example, they can be arranged at 90 degree intervals on a virtual circle drawn around an arbitrary point on one main surface. Each of these four antenna elements includes a vertical portion that is substantially perpendicular to the one main surface, and a horizontal portion that extends substantially parallel to the one main surface at the end of the vertical portion opposite to the one main surface. And is generally L-shaped. A feeding circuit is connected to the vertical portions of these four antenna elements. This power supply circuit supplies power to these vertical portions with a phase difference of 90 degrees from each other.

  In this circularly polarized antenna, the four antenna elements are mechanically arranged at intervals of 90 degrees and are fed with a phase difference of 90 degrees from each other, so that circularly polarized waves can be transmitted and received. In addition, since power is fed directly to the vertical portion of the antenna element, no electromagnetic coupling wire is required, and the configuration is simplified. Moreover, since the four antenna elements are formed in an L shape, the height dimension is short, and the circularly polarized antenna can be miniaturized.

  These four antenna elements can also be formed by metal bars. In this case, each antenna element can be manufactured by a simple operation of bending a metal rod having a predetermined length in the middle.

  The four antenna elements can be formed on the outer surface of a cylindrical body made of an insulator. It is desirable that the cylindrical body is obtained by rounding a flexible insulating film, for example. If comprised in this way, four antenna elements can be easily manufactured, for example by an etching etc., and it can fix simultaneously four antenna elements by fixing a cylindrical body on a board | substrate.

  Furthermore, the four antenna elements can tilt the joint between the vertical portion and the horizontal portion. By configuring in this way, the impedance can be easily adjusted by changing the tilt state, and the configuration can be simpler than providing an electromagnetic coupling line.

  The total length of the four antenna elements is preferably about ¼ of the wavelength λ of the signal to be transmitted or received. For example, it is desirable that the horizontal portion and the vertical portion each have a length of λ / 8. As described above, when the total length is λ / 4, it is possible to satisfactorily receive circularly polarized radio waves.

  Four parasitic elements can be provided outside the four antenna elements so as to correspond to the four antenna elements, respectively. In this case, since the parasitic element is provided corresponding to each antenna element, the half width can be widened.

  As described above, when four parasitic elements are provided, the four antenna elements are formed on the outer surface of a cylindrical body made of an insulator, and are spaced so as to surround the outer surface of the cylindrical body. It is also possible to form four parasitic elements on the outer surface of another arranged insulating cylindrical body. In this case, not only the antenna element but also the parasitic element can be easily manufactured and can be easily attached.

  It is also possible to provide a power supply circuit on the substrate. If comprised in this way, a circularly polarized wave antenna can be comprised further small.

  As described above, according to the present invention, a compact circularly polarized antenna having a simple configuration can be obtained.

  The circularly polarized antenna according to the first embodiment of the present invention is for receiving, for example, a circularly polarized wave in the 2 GHz band, and has a substrate 2 as shown in FIGS. 1 (a) and 1 (b). Yes. The substrate 2 is a rectangular one made of, for example, an insulator and has opposed main surfaces 2a and 2b. As shown in FIG. 1B, the substrate 2 has a length of about ¼ of a wavelength λ of a center frequency (about 2.3 GHz) of a radio wave to be received at a predetermined interval on the main surface 2b side. Are arranged on a reference potential portion, for example, on the ground plate 4.

  Four antenna elements 6 are formed on the main surface 2 a of the substrate 2. As shown in FIG. 1A, these antenna elements 6 are arranged at intervals of about 90 degrees around a center point drawn at an arbitrary position on the main surface 2a of the substrate 2. These antenna elements 6 are made of a metal rod, for example, and have a horizontal portion 6a substantially parallel to the main surface 2a. At one end portion of these horizontal portions 6a, a vertical portion 6b extending downward and perpendicular to the horizontal portions 6a is formed. That is, these antenna elements 8 are formed in an L shape, and are formed at intervals of 90 degrees in the same direction.

  Each of the horizontal portion 6a and the vertical portion 6b of the antenna element 6 has a length of about 1/8 of the reception wavelength λ, for example, and the total length is about λ / 4. For example, the horizontal portion 6a has a length of about 19.5 mm, and the vertical portion 6b has a length of about 17 mm. The antenna element 6 constitutes one antenna element by the horizontal portion 6a and the vertical portion 6b. In addition, the distance between the horizontal parts 6a located in parallel with each other is about 15 mm. The height of the antenna element 6 is small because it is bent from the middle so as to form the horizontal portion 6a while maintaining the total length of about λ / 4.

  On the main surface 2a of the substrate 2, a power feeding circuit 8 is formed as shown in FIG. The power feeding circuit 8 is directly soldered to the lower end portion of the vertical portion 6 b of each antenna element 6. The feeding circuit 8 is formed so that the antenna elements 6 can be fed with a phase difference of 90 degrees from each other. Note that the configuration of the power supply circuit 8 is a known one, and a detailed description thereof will be omitted. As described above, the feeding circuit 8 is directly connected to the vertical portion 6b of the antenna element 6, and unlike the above-described conventional technique, an electromagnetic coupling line is not required.

  The power supply circuit 6 is connected to a circularly polarized coaxial plug provided on the substrate 2 (not shown). Since each antenna element 6 is mechanically arranged with a difference of 90 degrees from each other and is fed with a phase difference of 90 degrees with each other, circularly polarized waves can be transmitted and received by these antenna elements 6. In this embodiment, each antenna element 6 is arranged and electrically connected so as to receive the left-handed circularly polarized wave.

  A monopole antenna 10 for receiving linearly polarized waves is provided at substantially the center of the space surrounded by each antenna element 6. The lower end portion of the monopole antenna 10 is connected to the antenna power supply circuit 12. Although not shown in the figure, the power feeding circuit 12 is connected to a monopole antenna plug provided on the substrate 2.

  FIG. 2 shows vertical directivity characteristics on the x and z planes in the x, y, and z coordinates shown in FIGS. 1A and 1B among the vertical directivity characteristics of this antenna. FIG. Of the vertical directivity characteristics, the vertical directivity characteristics in the y and z planes are shown. As can be seen from both figures, the full width at half maximum is shown on both sides. Note that the directional characteristics in the x and y planes, that is, the horizontal directional characteristics indicate omnidirectional characteristics.

  A circularly polarized wave antenna according to a second embodiment of the present invention is shown in FIGS. The circularly polarized antenna of this embodiment is also for receiving circularly polarized radio waves in the 2 GHz band. As shown in FIGS. 4A, 4B, and 5, the antenna element 60 is made of an insulator. A cylindrical body, for example, a cylindrical body 62 is formed.

  Cylindrical body 62 is arranged on main surface 2 a of substrate 2. The cylindrical body 62 is formed by rounding a rectangular flexible insulating film. A plurality, for example, four antenna elements 60 are formed on the outer surface side of the cylindrical body 62. These antenna elements 60 are formed, for example, by etching a conductive film, for example, a metal film, formed by vapor deposition or the like on the outer surface of an insulator film.

  A total of four antenna elements 60 are formed at intervals of 90 degrees on the surface of the cylindrical body 62 with the center of the cylindrical body 62 as the center. Each of these antenna elements 60 has a horizontal portion 60a. These horizontal portions 60a are arranged substantially parallel to the main surface 2a. At one end of these horizontal portions 60a, a vertical portion 60b is formed substantially perpendicular to the horizontal portion 60a toward the main surface 2a side.

  The horizontal portion 60a is formed to have a length of, for example, about 13 mm, and the vertical portion 60b is formed to have a length of, for example, about 12 mm. The horizontal portion 60a and the vertical portion 60b each have a length of about λ / 8.

  As shown in FIGS. 4 and 5, an inclined portion 60c is formed at the coupling portion between the horizontal portion 60a and the vertical portion 60b, and impedance matching is performed.

  The lower ends of these vertical portions 60b are coupled, for example, soldered, to the respective end portions of the feeder circuit 80 formed on the main surface 2a. Since the power feeding circuit 80 is configured in substantially the same manner as the power feeding circuit 8 of the first embodiment, detailed description thereof is omitted.

  Also in the second embodiment, the electrical connection between each antenna element 60 and the power feeding circuit 80 is made directly, and an electromagnetic induction coupling circuit is not required, and the connection work can be easily performed.

  FIG. 6 shows the vertical directivity characteristics on the x and z planes in the x, y and z coordinates shown in FIGS. 4A and 4B among the vertical directivity characteristics of this antenna, and FIG. The vertical directivity characteristic in the plane is shown. As can be seen from both figures, the full width at half maximum is shown on both sides. Note that the directional characteristics in the x and y planes, that is, the horizontal plane directional characteristics indicate omnidirectional characteristics.

  8 to 10 show a circularly polarized antenna according to the third embodiment. This circularly polarized antenna is obtained by providing a parasitic element to the circularly polarized antenna of the second embodiment. The configuration other than the parasitic element is the same as that of the circularly polarized antenna of the second embodiment. ing. Equivalent parts are denoted by the same reference numerals and description thereof is omitted. In FIG. 8B, since the figure is complicated, the feeding circuit 80 and the monopole antenna 10 are not shown.

  As shown in FIG. 9, on the outer periphery of the cylindrical body 62, another cylindrical body, for example, the cylindrical body 12 is formed on the main surface 2 a of the substrate 2 concentrically with the cylindrical body 62 so as to surround the cylindrical body 62. Has been placed. Similarly to the cylindrical body 62, the cylindrical body 12 is also a cylindrical body having a diameter larger than that of the cylindrical body 62 by rounding a rectangular flexible insulating film. Its height dimension is shorter than that of the cylindrical body 62. The interval between the cylindrical body 12 and the cylindrical body 62 is set to about 4 mm (about 0.04λ).

  Four parasitic elements 14 are provided on the outer surface of the cylindrical body 12 at intervals of 90 degrees so as to correspond to the antenna elements 60. These parasitic elements 14 are formed along the surface of the cylindrical body 12 parallel to the main surface 2a, and the length along the cylindrical body 16 is about 20 mm (about 0.15λ), and the horizontal portion 8a. It is formed longer than. Each parasitic element 14 is formed at a height of about 5 mm (about 0.04λ) from the main surface 2a. Therefore, each of the vertical portions 60b of each antenna element 60 intersects with the vertical portions 60b. The parasitic element 14 has a width of about 2 mm. Each parasitic element 14 can be formed by using an insulating film having a metal thin film deposited on one surface as a material of the cylindrical body 12 and etching it.

  The solid line in FIG. 10 shows the vertical directivity characteristics in the x and z planes of this circularly polarized antenna (the x and z planes are the same as the x and z planes in the second embodiment). Therefore, when the parasitic element 14 is removed from the circularly polarized antenna, that is, the vertical directivity characteristics in the x and z planes of the circularly polarized antenna of the second embodiment are indicated by broken lines. From the comparison of the two, it is clear that the half-value width is widened by providing the parasitic element 14.

  In the second and third embodiments described above, the antenna element 60 is provided on the outer surface of the cylindrical body 62 by etching. However, the present invention is not limited to this. For example, as in the first embodiment. An antenna element obtained by bending a metal rod into an L shape can also be used. Although the antenna element 60 is formed in the cylindrical body 62, it is not restricted to this, For example, it can also be formed in a square cylinder body. In each of the above-described embodiments, the power feeding circuits 8 and 80 are provided on the main surface 2a side of the substrate 2. However, the power feeding circuits can be provided on the main surface 2b side, or a power feeding circuit is provided separately from the substrate 2. It can also be provided. Similarly, the parasitic element 14 in the third embodiment is also provided in the cylindrical body 12 by etching. However, the parasitic element 14 is not limited to this, and a linear metal rod is attached to the antenna element 60 by an appropriate support. It can also be arranged near the vertical part.

It is the top view and front view of the circularly polarized antenna of 1st Embodiment of this invention. FIG. 2 is a directional characteristic diagram in the x and z planes of the circularly polarized antenna of FIG. 1. It is a directional characteristic diagram in the y and z plane of the circularly polarized antenna of FIG. It is the front view and top view of a circularly polarized wave antenna of 2nd Embodiment of this invention. It is a perspective view of the cylindrical body in which the antenna element in the circularly polarized antenna of FIG. 4 is formed. FIG. 5 is a directional characteristic diagram in the x and z planes in the x and z planes of the circularly polarized antenna in FIG. 4. FIG. 5 is a directional characteristic diagram in the y and z planes of the circularly polarized antenna of FIG. 4. It is the front view and top view of the circularly polarized wave antenna of the 3rd Embodiment of this invention. It is a perspective view of the cylindrical body in which the antenna element in the circularly polarized antenna of FIG. 8 is formed, and the cylindrical body in which the parasitic element is formed. FIG. 9 is a directional characteristic diagram in the x and z planes of the circularly polarized antenna of FIG. 8 and the antenna of FIG. 4.

Explanation of symbols

2 Substrate 6 60 Antenna element 6a 60a Horizontal portion 6b 60b Vertical portion 8 80 Feed circuit 12 Cylindrical body 14 Parasitic element 62 Cylindrical body (cylindrical body)

Claims (8)

A substrate having two opposing major surfaces;
On one main surface of the substrate, the substrate is arranged at intervals of approximately 90 degrees, and each of the vertical portions is substantially perpendicular to the one main surface, and the vertical portion has an end opposite to the one main surface. Four generally L-shaped antenna elements having a horizontal portion extending substantially parallel to one main surface;
A circularly polarized antenna having a feeding circuit connected to the vertical portions of these four antenna elements and feeding power with a phase difference of 90 degrees from each other.   The circularly polarized antenna according to claim 1, wherein each antenna element is formed of a metal rod.   2. The circularly polarized wave antenna according to claim 1, wherein the four antenna elements are formed on an outer surface of a cylindrical body made of an insulator.   4. The circularly polarized antenna according to claim 3, wherein the four antenna elements are inclined at a joint portion between the vertical portion and the horizontal portion.   2. The circularly polarized antenna according to claim 1, wherein the four antenna elements have a total length that is about 1/4 of a wavelength of a signal to be transmitted / received. The circularly polarized wave antenna according to claim 1, wherein four parasitic elements provided respectively corresponding to the four antenna elements are provided outside the four antenna elements.
A circularly polarized antenna.   7. The circularly polarized antenna according to claim 6, wherein the four antenna elements are formed on an outer surface of a cylindrical body made of an insulator, and the four parasitic elements are formed with the four antenna elements. A circularly polarized wave antenna formed on the outer surface of another insulating cylindrical member disposed so as to surround the outer surface of the cylindrical member.   The circularly polarized antenna according to claim 1, wherein the feeding circuit is provided on the substrate.

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