JP2009159225A - Antenna device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna device omnidirectional in a horizontal plane, and capable of responding to a plurality of polarized waves, and providing a uniform omnidirectional pattern in a horizontal plane. <P>SOLUTION: This antenna device 100 includes: a cylindrical conductor 20; a first-stage patch antenna array 11 having patch antennas 10a-10d arranged around the circumference of the conductor 20, at equal distances from the outer peripheral surface thereof, and at equal intervals from one another; and a second-stage patch antenna array 12 having patch antennas 10e-10h arranged around the circumference of the conductor 20, at equal distances from the outer peripheral surface thereof, and at equal spacings from one another, and arranged in parallel to the first-stage patch antenna array 11 at a position rotatively moved from the first-stage patch antenna array 11 around a cylinder axis of the conductor 20. Each of the patch antennas 10a-10h constituting the first-stage and second-stage patch antenna arrays 11 and 12 has two power-feed ports fed with power by the same power feed circuit, and each power-feed port is subjected to phase-difference power feed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an antenna device, and more particularly to an omnidirectional antenna device in a horizontal plane that can handle a plurality of polarized waves used in a base station or the like in a mobile communication system.

2. Description of the Related Art A base station antenna for a mobile phone is known in which a plurality of patch antennas are arranged in an array to ensure an omnidirectional pattern in a horizontal plane. As an example of such an antenna device, the antenna devices described in Patent Documents 1 to 3 can be referred to.
In the antenna devices described in Patent Documents 1 to 3, an antenna array is formed by using a plurality of patch antennas on the outer peripheral surface of a substrate having a polygonal cylinder or cylinder shape, thereby generating omnidirectional pattern radiation in a horizontal plane. Configured to do.
US Patent Publication No. 2004 / 0174303A1 US Pat. No. 6,791,507 B2 International Publication No. 92/17915 Pamphlet

  However, in an antenna device configured by arranging a plurality of patch antennas in an array on the cylindrical surface in this way, the omnidirectional pattern in the horizontal plane usually has a fluctuation of about 2 to 3 dB. Therefore, it is difficult to realize a uniform omnidirectional radiation pattern. Conventionally, such an antenna device is only compatible with a single polarization, and it is desirable to be able to support a plurality of polarizations when assuming application of polarization diversity for further improvement in communication quality. .

  Further, the horizontally polarized omnidirectional antenna device provided with the patch antenna array generally has a complicated structure as compared with typical vertically polarized omnidirectional antenna devices such as a monopole antenna and a dipole antenna. Therefore, it is necessary to consider reducing the influence of manufacturing errors on various characteristics of the antenna. Since a plurality of patch antennas are used, it is also required to devise an arrangement so that the antenna device does not increase in size.

  In view of these points, the horizontal plane omnidirectional antenna device provided by the present invention that can handle multiple polarizations is arranged at equal intervals from the outer peripheral surface around the circumference of the cylindrical conductor and the circumference of the conductor. A first-stage patch antenna array having four patch antennas and four patch antennas arranged at equal intervals from the outer peripheral surface around the circumference of the conductor, and centering on the cylindrical axis of the conductor A second-stage patch antenna array disposed in parallel with the first-stage patch antenna array at a position rotationally moved from the first-stage patch antenna; Each patch antenna constituting the first-stage and second-stage patch antenna arrays has two feeding ports fed by the same feeding circuit, and each feeding port is fed with phase difference feeding.

  Further, the horizontal plane omnidirectional antenna device further capable of supporting a plurality of polarized waves provided by the present invention is arranged with a cylindrical conductor and equidistant from the outer peripheral surface around the circumference of the conductor. A first-stage patch antenna array having two patch antennas, and four patch antennas arranged equidistantly from the outer peripheral surface around the circumference of the conductor and having a first axis centered on the cylindrical axis of the conductor A second-stage patch antenna array disposed in parallel to the first-stage patch antenna array at a position where the first patch antenna array is rotated, and the first-stage patch antenna array and the second-stage patch antenna array; A plurality of sets are arranged in a balanced manner along the outer periphery of the conductor, and the patch antennas constituting the first-stage and second-stage patch antenna arrays are supplied by the same feeder circuit. Has two feeding ports, each feeding port is powered phase difference.

  In these antenna devices, the first-stage patch antenna array and the second-stage patch antenna array are arranged at positions where one is rotated by 45 ° from the other around the cylindrical axis of the conductor, Each power feeding port is fed with a + 45 ° phase difference or −45 ° phase difference, and transmits / receives + 45 ° polarization or −45 ° polarization.

  Alternatively, in these antenna devices, each feeding port of each patch antenna is further supplied with in-phase feeding, anti-phase feeding, + 90 ° phase difference feeding or −90 ° phase difference feeding, and vertically polarized waves, horizontally polarized waves, right-handed circles. Polarization or left-hand circular polarization may be transmitted and received. Furthermore, in the antenna device of the present invention, each patch antenna has a circular shape or a 4 × n polygonal shape that is symmetric with respect to a horizontal axis, a vertical axis, or a 45 ° axis passing through the center of the patch.

  The antenna device of the present invention has a configuration in which the first-stage patch antenna array and the second-stage patch antenna array are arranged at positions where one is rotated from the other around the cylindrical axis of the conductor. It is possible to improve the omnidirectionality in the horizontal plane as compared with the conventional antenna device, and obtain a uniform horizontal omnidirectional pattern. Further, by making the power supply circuits for a plurality of polarized waves the same, the isolation between the power supply ports can be increased, and the reflection characteristics of each power supply port can be improved. Since the plurality of patch antennas are arranged alternately, an increase in the size of the antenna device is avoided.

  Therefore, according to the present invention, all directions in a horizontal plane capable of dealing with a plurality of polarized waves having a small size, a small diameter, good isolation characteristics between two power supply ports, and good reflection characteristics of each power supply port. A directional antenna device can be provided. Furthermore, transmission / reception of vertically polarized waves, horizontally polarized waves, and right / left-handed circularly polarized waves can be made possible by the configuration of the feeding circuit.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a horizontal omnidirectional antenna apparatus according to an embodiment of the present invention. The antenna device 100 includes a cylindrical conductor 20 and a first-stage patch antenna array 11 and a second-stage patch antenna array 12 arranged on the outer periphery of the conductor 20.

  FIGS. 2A and 2B are top views of the antenna device 100 showing the positional relationship between the patch antennas of the first-stage patch antenna array 11 and the second-stage patch antenna array 12. As shown in the figure, the first-stage patch antenna array 11 is composed of four patch antennas 10a, 10b, 10c, and 10d that are arranged on the outer periphery of a cylindrical conductor 20 at 90 ° intervals. The second stage patch antenna array 12 includes four patch antennas 10e, 10f arranged at 90 ° intervals at positions where the patch antennas 10a, 10b, 10c, 10d are rotated by 45 ° about the cylindrical axis. It consists of 10g and 10h.

  Each patch antenna 10 is disposed on the surface of a dielectric 31 that covers the outer periphery of the conductor 20, for example, as shown in FIG. Or as shown in FIG.3 (b), you may arrange | position on the conductor 20 using the support | pillar 32 which consists of dielectric materials. At this time, if the distance between the patch antenna 10 and the conductor 20 is too long, undesired polarization is radiated, which is not preferable. In addition, if it is too close, there is a problem that the antenna becomes a narrow band. Accordingly, the patch antenna 10 is appropriately arranged according to a necessary band in consideration of these problems.

FIG. 4 schematically shows the configuration of the antenna device 100 on a plane. Each of the patch antennas 10a to 10h includes two power supply ports 1, 1 ', 2, 2' ..., and each of the power supply ports 1, 1 ', 2, 2' ... has the same power supply circuit. Is fed with a + 45 ° phase difference or −45 ° phase difference. Power feeding is performed from the inside of the conductor 20 via a pin or the like (not shown).
Here, prior to the description of the operation of the antenna apparatus 100 having such a two-stage patch antenna array, an antenna apparatus configured with only one patch antenna array will be described with reference to FIGS.

  FIG. 6 shows an antenna device 110 including a cylindrical conductor 20 and a one-stage patch antenna array 13 arranged on the outer periphery of the conductor 20. In this antenna device 110, the patch antenna array 13 is composed of four patch antennas 10 i, 10 j, 10 k, and 10 l disposed on the outer periphery of the conductor 20 at 90 ° intervals.

  FIG. 7 schematically shows the configuration of the antenna device 110 on a plane. Each of the patch antennas 10i to 10l includes power supply ports 1, 2, 3, and 4, and each of the power supply ports 1 to 4 has a phase difference corresponding to the arrangement angle of the patch antennas 10i to 10l, that is, a phase difference of 90 °. Power is supplied at. At this time, for example, if the outer circumference of the conductor 20 is 3λ and the size and shape of the patch antenna element is a square having a side of λ / 2, the patch antennas 10i to 101 are spaced apart from each other by about λ / 4. When considering the feeding phase to each of the patch antennas 10i to 10l, for example, there are two types of phase differences as shown in the table of FIG.

  FIG. 8 is a diagram showing a horizontal plane radiation pattern variation of the antenna device 110. As shown in the figure, the horizontal radiation pattern of the antenna device 110 has a variation of 4 Hz at an azimuth angle AZ0 ° to 360 °. That is, if the patch antenna array has only one stage, fluctuations appear in the radiation pattern on the horizontal plane, and it is difficult to achieve uniform omnidirectionality.

  Therefore, in order to cancel this fluctuation, the antenna device 100 according to the embodiment of the present invention uses a combination of two-stage patch antenna arrays. As described above, the first-stage antenna array 11 and the second-stage antenna array 12 are arranged so as to be shifted by 45 ° about the cylindrical axis of the conductor 20. Therefore, the patch antennas 10a to 10d and 10e to 10h on the conductor 20 are alternately arranged at 45 ° intervals. And in the power feeding ports 1 to 8 of the patch antennas 10a to 10h, power is fed with a + 45 ° phase difference corresponding to the angle of arrangement.

  FIG. 5 shows the pattern variation on the horizontal plane of such an antenna device 100. As shown in the figure, in this antenna device 100, the radiation pattern on the horizontal plane is substantially uniform in all directions of the azimuth angles AZ0 ° to 360 °. That is, it can be seen that the omnidirectionality in the horizontal plane can be improved as compared with the antenna device 110 having only one stage of the antenna array.

  As described above, by providing the two-stage antenna arrays 11 and 12, the antenna device 100 can realize good omnidirectionality in the horizontal plane. In addition, the gain can be increased by using a multistage configuration including a plurality of antenna arrays. Therefore, for example, as in another embodiment of the present invention shown in FIG. A set (11a, 12a, 11b, 12b...) Of stacked antenna devices 120 can also be used.

  By the way, in the antenna devices 100 and 110 having the two-stage or single-stage antenna array as shown in FIGS. 1 and 6, the radiation is actually performed by performing in-phase power feeding rather than the above-described phase power feeding. Variations in the pattern can be reduced. However, the reason why phase feeding is performed in these antenna devices is because of the following advantages.

  In the antenna devices 100 and 110, the patch antennas 10 are arranged symmetrically on the cylindrical conductor 20, and the reflection characteristics and the pass characteristics between orthogonal ports (for example, between the port 1 and the port 1 ') are the same. It is. Here, FIG. 10 shows an example of a power feeding circuit. In the present invention, when the feeding circuits of the patch antennas 10a to 10d constituting the first stage antenna array 11 are configured as shown in FIG. 10, the reflected waves of the patch antennas 10a to 10d are 90 ° hybrid circuits 40a to 40 °. It appears in the 40d isolation port, but not in the ports connected to the 180 ° hybrid circuits 501 and 502. Similarly, the passing waves of the patch antennas 10a to 10d appear only in the isolation ports of the 90 ° hybrid circuits 40a to 40d, and do not appear in the ports connected to the 180 ° hybrid circuits 501 and 502.

  In this way, most of the characteristic defects such as reflection characteristics, isolation characteristics, and omnidirectionality caused by manufacturing errors can be absorbed by the 90 ° hybrid circuit isolation port, which improves the product defect rate. It can contribute greatly.

  On the other hand, when in-phase power feeding is performed, the reflection characteristics and the orthogonal port passing characteristics of the patch antennas 10a to 10d appear as they are at the ± 45 ° polarization port. That is, unlike the case of phase difference feeding, characteristic defects such as reflection characteristics, isolation characteristics, and omnidirectionality caused by manufacturing errors and the like appear in the ± 45 ° polarization port as they are. Furthermore, if the ± 45 ° polarization port is not perfectly matched, multiple reflections in the power feeding circuit occur, and there is a problem that omnidirectionality and polarization separation characteristics are deteriorated. Therefore, it can be said that it is more preferable to perform phase difference feeding.

  10 includes a 90 ° hybrid circuit as shown in FIG. 11A or a 180 ° as shown in FIG. 11B at the ± 45 ° polarization ports of the 180 ° hybrid circuits 501 and 502. ° It is also possible to connect more hybrid circuits. As a result, a right-handed / left-handed circularly polarized wave and a vertically / horizontally polarized wave antenna can be configured.

  In the antenna device of the present invention, the antenna element shape of the patch antenna is not limited to a square, but a shape that can radiate two orthogonally polarized waves, that is, a shape that is symmetric with respect to a horizontal axis, a vertical axis, and a 45 ° axis passing through the center of the patch. Any shape is acceptable. Therefore, it may be circular as shown in FIG. 12 (a), or it may be a 4 × n polygon as shown in FIGS. 12 (b) to 12 (d). Regardless of the shape, it is possible to achieve the same performance as in the case of a square.

The preferred embodiment of the present invention has been described above, but the present invention is not limited to this, and various other embodiments can be implemented by appropriately changing the arrangement of the patch antenna and the feeding method, for example.
Therefore, in-phase feeding, reverse phase feeding, + 90 ° phase difference feeding or -90 ° phase difference feeding is performed at the feeding port of each patch antenna, and vertical polarization, horizontal polarization, right-handed circular polarization, or left-handed circular polarization An antenna device capable of transmitting and receiving can also be used.

The figure which shows one Example of the antenna device of this invention. The figure explaining arrangement | positioning of the patch antenna in the antenna apparatus of this invention. The figure explaining arrangement | positioning of the patch antenna in the antenna apparatus of this invention. FIG. 6 illustrates a structure of an antenna device of the present invention. The figure which shows the radiation pattern fluctuation | variation in the horizontal surface of the antenna apparatus of this invention. The figure which shows the antenna apparatus for a comparison with this invention. The figure explaining the structure of the antenna apparatus for a comparison. The figure which shows the radiation pattern fluctuation | variation in the horizontal surface of the antenna apparatus for a comparison. The figure which shows another Example of the antenna apparatus of this invention. The figure which shows an example of the electric power feeding circuit of the antenna apparatus of this invention. The figure which shows the hybrid circuit which can be added to the electric power feeding circuit of the antenna apparatus of this invention. The figure which shows the modification of the shape of the patch antenna used for the antenna apparatus of this invention.

Explanation of symbols

100, 110, 120 Antenna device 10, 10a-10l Patch antenna 11, 11a-11e First stage patch antenna array 12, 12a-12e Second stage patch antenna array 13 Patch antenna array 20 Conductor 31, 32 Dielectric 40a -40d 90 ° hybrid circuit 501, 502 180 ° hybrid circuit

Claims (5)

A cylindrical conductor;
A first-stage patch antenna array having four patch antennas arranged equidistantly around the circumference of the conductor and equidistant from the outer peripheral surface;
A position having four patch antennas arranged equidistantly from the outer circumferential surface around the circumference of the conductor and rotated from the first stage patch antenna about the cylindrical axis of the conductor A second-stage patch antenna array disposed in parallel with the first-stage patch antenna array;
With
Each of the patch antennas constituting the first-stage and second-stage patch antenna arrays has two feeding ports that are fed by the same feeding circuit,
An omnidirectional array antenna device in a horizontal plane capable of supporting a plurality of polarized waves, wherein each of the feeding ports is fed with a phase difference. A cylindrical conductor;
A first-stage patch antenna array having four patch antennas arranged equidistantly around the circumference of the conductor and equidistant from the outer peripheral surface;
A position having four patch antennas arranged equidistantly from the outer circumferential surface around the circumference of the conductor, and the first stage patch antenna being rotated around the cylindrical axis of the conductor A second-stage patch antenna array disposed in parallel with the first-stage patch antenna array;
With
A plurality of sets of the first-stage patch antenna array and the second-stage patch antenna array are arranged in parallel along the outer periphery of the conductor,
Each of the patch antennas constituting the first-stage and second-stage patch antenna arrays has two feeding ports that are fed by the same feeding circuit,
An omnidirectional array antenna device in a horizontal plane capable of supporting a plurality of polarized waves, wherein each of the feeding ports is fed with a phase difference. The antenna device according to claim 1 or 2,
The first-stage patch antenna array and the second-stage patch antenna array are arranged at positions where one is rotated by 45 ° from the other around the cylindrical axis of the conductor,
Each feeding port of each patch antenna is fed with a + 45 ° phase difference or −45 ° phase difference and can transmit / receive a + 45 ° polarized wave or −45 ° polarized wave. Horizontal plane omnidirectional array antenna device. The antenna device according to claim 3, wherein
Each feeding port of each patch antenna is further supplied with in-phase feeding, anti-phase feeding, + 90 ° phase difference feeding or −90 ° phase difference feeding, and vertically polarized waves, horizontally polarized waves, right-handed circularly polarized waves, or left-handed circularly polarized waves. An omnidirectional array antenna device in a horizontal plane capable of dealing with a plurality of polarized waves, characterized by transmitting and receiving waves. The antenna device according to any one of claims 1 to 4,
Each patch antenna has a circular shape or a 4 × n polygonal shape symmetric with respect to a horizontal axis, a vertical axis, or a 45 ° axis passing through the center of the patch. Antenna device.

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