JPH0927714A - Multibeam antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit and receive not only a vertical polarized wave, but also a horizontal polarized wave at the same time and generate multibeams or sector beams almost equally in all directions of a horizontal plane. SOLUTION: On the outer peripheral surface of a cylindrical metallic reflecting plate 15, plural helical antenna elements 16 are arranged in an array shape circumferentially and axially at specific pitches. Cross dipole antenna elements are usable instead of the helical antenna elements. The beam tilt and gain can be improved by the axial antenna array and the multibeams or sector beams can be generated almost equally in all directions of the horizontal plane by the circumferential antenna array.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is installed and used in a base station device such as an automobile or a mobile phone system.
The present invention relates to an antenna device capable of forming multi-beams or sector beams in all directions in a horizontal plane and transmitting / receiving circularly polarized waves.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 8, an antenna of a mobile telephone mobile station has a trunk lid antenna 1 or a roof top antenna 2 installed vertically on a vehicle, and in most radio wave environments, the main polarized wave is used. Was a vertically polarized wave A1 component. Therefore, as shown in FIG. 9, a vertically polarized A1 dipole antenna 4 provided with a reflector 3 as an element antenna has been used in an antenna installed in an automobile / cell phone type base station device.

However, in recent years, due to the rapid spread of mobile phones, the number of mobile phone subscribers has exceeded the number of mobile phone subscribers, resulting in a change in the radio wave environment used. That is, as shown in FIG. 10, the antenna 5 of this mobile phone is used.
a is not always used vertically while talking, and the electromagnetic wave to be transmitted from it is sufficiently large not only in the vertically polarized wave A1 but also in the horizontally polarized wave A2, and is also transmitted from the base station in reception. Since the radio waves are vertically polarized waves A1, the antenna could not be received with sufficient efficiency when the antenna was inclined.

Therefore, when receiving or transmitting an electromagnetic wave from such a mobile station to the mobile station, the base station antenna is required to have a characteristic capable of transmitting and receiving a horizontal polarization component as well as a vertical polarization component. However, it is difficult for the conventional vertically polarized dipole antenna 4 to transmit / receive horizontally polarized waves. On the other hand, when applying the multi-beam or sector-beam method to the base station antenna for advanced zone formation such as gain improvement or interference suppression, FIG.
As shown in FIG. 1A, it is considered to install a plurality of rectangular flat plate array antennas 6, 7, and 8. However, as shown in FIG. 12, the beam generated from a single flat plate array antenna becomes oblique from the front direction 9 of the array surface, and the aperture area of the antenna seen from the incoming electromagnetic wave decreases from 10 to 11. Therefore, the gain was deteriorated. Therefore, as shown in FIG. 11B, the array antennas 6, 7 and 8 are arranged in zones 6z, 7z and 8z, respectively.
Therefore, it was difficult to form a uniform zone in all directions in the horizontal plane because the gain was lowered in the directions 12, 13 and 14. Here, for example, the zone 7z is composed of a plurality of beams 7b. In particular, when a circularly polarized wave antenna is used as the element antenna, the tendency of the gain decrease becomes noticeable at the angles other than the front direction due to the deterioration of the axially polarized wave characteristic of the circularly polarized wave. Was there.

[0005]

SUMMARY OF THE INVENTION In order to realize the above requirements, the present invention enables a base station to simultaneously transmit and receive not only vertically polarized waves but also horizontally polarized waves, and multi-beams or sector beams in all directions in a horizontal plane. The purpose is to construct an array antenna that can transmit and receive almost uniformly.

[0006]

In order to solve the above-mentioned problems, the present invention provides a helical antenna element or a crossed dipole antenna element having a good circular polarization characteristic in a matrix form on the cylindrical surface in the circumferential direction and the axial direction. I have installed multiple. This makes it possible to cover the inside of the zone with multi-beams having uniform gain and axial ratio characteristics.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

(1) An embodiment of the invention of claim 1 is shown in FIG. Helical antenna elements 16 are arranged on the cylindrical metal reflector 15 in the axial direction and the circumferential direction at substantially the same pitch intervals.
The helical antenna 16 has a circular polarization axis mode characteristic as shown in FIG. This axial mode helical antenna 16
Has a sharp beam 17 only in the axial direction and has good axial ratio characteristics in this direction. The axial array 16A composed of a plurality of antenna elements arranged in the axial direction of the cylinder is shown in FIG.
As shown in FIG. 5, it is provided for improving the beam tilt and the gain. Here, each helical antenna element 16 is physically tilted downward to perform beam tilt (claim 4), and is installed while electrically changing the phase, or at right angles to the outer peripheral surface, that is, in the radial direction. (Claim 5),
Moreover, the phase is electrically changed to supply power.

The circumferential array 16B is provided for a multi-beam or sector beam configuration, as shown in FIG. In FIG. 4, the half width is 30 ° and the number of beams is 12
The individual multi-beams are configured. In this case, 12 axial mode helical antennas having a 30 ° beam are evenly arranged in the circumferential direction. With such an arrangement, the base station beam can be captured within a deviation of 3 dB even if the mobile station exists in an arbitrary direction, and adaptively using a plurality of arbitrary adjacent beams. Even in the case of beam-forming, the aperture areas 18 and 19 seen from the mobile station can be always kept constant as shown in FIG. That is, it is possible to form a zone in which circularly polarized waves can be uniformly transmitted and received in all directions in the horizontal plane. Others, half-width of 15 °
It can be configured such that the product of the half width and the number of beams is 360 °, such as the number of 24 beams. (2) An embodiment of the invention of claim 2 is shown in FIG. The crossed dipole antenna elements 20 are arranged on the cylindrical metal reflector 15 in a matrix in the axial direction and the circumferential direction. The cross dipole antenna element 20 has circular polarization axis mode characteristics as shown in FIG. Except that the element antennas are different, the configuration is similar to that of the embodiment (1), and the beam characteristics are almost the same.

[0009]

As described above, according to the present invention, since a uniform circularly polarized multi-beam or sector beam can be obtained within a predetermined zone, a weak electric field region or a region with a weak horizontal polarization component is generated. In addition, since it is possible to receive not only the vertically polarized wave but also the horizontally polarized wave, it is possible to always maintain good call quality not only when using a mobile phone but also when using a mobile phone.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining a helical antenna having an axial mode and its polarization.

FIG. 3 is a diagram for explaining an axial array and a beam tilt.

FIG. 4 is a diagram for explaining a circumferential array and multi-beams.

FIG. 5 is a view for explaining a circumferential array and an opening area.

FIG. 6 is a perspective view showing an embodiment of the invention of claim 2;

FIG. 7 is a diagram for explaining a crossed dipole antenna and polarized waves.

FIG. 8 is a diagram for explaining an antenna of a mobile telephone mobile station and its polarized wave.

FIG. 9 is a diagram for explaining a conventional dipole antenna installed in an automobile / mobile phone type base station device and its polarization.

FIG. 10 is a diagram illustrating an antenna of a mobile phone during a call.

11A is a perspective view showing the principle of a conventional base station multi-beam antenna, and FIG. 11B is a plan view for explaining the zone of A. FIG.

FIG. 12A is a plan view of a vertically arranged flat plate array antenna, and B is a graph for explaining the angle dependence of the antenna gain.

Claims (5)

[Claims] 1. A multi-beam antenna device, wherein a plurality of helical antenna elements are arranged in a matrix along a circumferential direction and an axial direction on an outer peripheral surface of a vertically arranged cylindrical metal reflector. . 2. A multi-beam antenna characterized in that a plurality of crossed dipole antenna elements are arranged in a matrix along a circumferential direction and an axial direction on an outer peripheral surface of a vertically arranged cylindrical metal reflector. apparatus. 3. The multi-beam antenna device according to claim 1, wherein the plurality of helical antenna elements or the crossed dipole antenna elements are arranged at substantially constant pitches in the circumferential direction and the axial direction, respectively. 4. The multi-beam antenna device according to claim 1, wherein the axis of the helical antenna element is arranged obliquely downward with respect to the radial direction of the cylindrical metal reflector. 5. The multi-beam antenna device according to claim 1, wherein an axis of the helical antenna element is arranged in a radial direction of the cylindrical metal reflector.