JP3323030B2 - Common antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shared antenna that is effective for both circularly polarized waves in satellite communications and vertically polarized waves in terrestrial communications. Related to a simple antenna.

[0002]

2. Description of the Related Art Currently, linearly polarized waves are used in mobile communications such as mobile phones. In recent years, various companies have proposed a concept of a mobile phone using a satellite, and an antenna for that purpose has been proposed. For example, a method of using a circularly polarized patch antenna for satellite communication and switching to a vertically polarized linear antenna for terrestrial base stations (non-geostationary satellite communication system No.261 in the ITU research world)
/ 262 New Japan ITU Association). The antenna shown in FIG. 4 is a common antenna for circularly polarized waves and linearly polarized waves, and two helical members (radiating elements 2 and 4) are wound around one cylindrical support member 8 in the opposite direction to supply power to both helical members. ON / O power supply near point
A method has been proposed in which an FF switch is provided to realize circular polarization by feeding only one helical, and to realize linear polarization by feeding both helicals.

[0003]

In satellite communications, the distance between a ground station and a satellite is extremely long, and radio waves must be made very weak.

[0004] Further, providing two antenna systems as described above in a small device such as a mobile phone has a problem in mounting space and impairing storability.

[0005]

In order to solve the above-mentioned problems, the present invention forms a radiation directivity suitable for each system by appropriately selecting parameters at the frequency of each system. An antenna which can be shared by expansion and contraction is provided as an antenna for mobile communication and an antenna for mobile satellite communication.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same parts are denoted by the same reference numerals, 1 is a support having an outer diameter d, 2 is a regular radiating element, 3 is an inner diameter D The support 4 is a counter-rotating radiating element.

First, a description will be given with reference to FIG. In a helical antenna, circular polarization can be obtained by selecting an appropriate size and shape. At this time, a similar helical antenna wound in the opposite direction can produce an antenna having circular polarization in the opposite direction. The electric field of a circularly polarized wave is rotated with time. If a normal circularly polarized wave and a reversely circularly polarized wave can be simultaneously generated with the same intensity, a linearly polarized wave can be obtained. FIG. 3 shows this principle, (a) shows a circularly polarized wave,
(B) shows reverse circular polarization, and (C) shows linear polarization by normal circular polarization and reverse circular polarization. Therefore, linear polarization can be obtained at the time of the reduction. In addition, communication can be performed with circularly polarized waves by selecting one of a normal rotation antenna and a reverse rotation antenna during extension.

FIG. 1 shows a first embodiment of the present invention and is a schematic configuration diagram of a helical antenna wound around two cylindrical bodies. The support 1 is a small-diameter cylindrical body having an inner diameter d, and forms a regular rotation radiating element 2 by winding a conductor around the inner circumference at a constant pitch. Support 3
Is a large-diameter cylindrical body having an outer diameter D around which the conductive wire is wound. The outer diameter of the support 1 is approximately equal to the inner diameter of the support 3, and the support 1 moves in the axial direction from the contracted state included in the support 3 to the extended state separated from the support 3 while being in contact with the inner wall. Change. The support 1 may be moved manually or mechanically or automatically automatically, but it is sufficient to use a movable member based on a known technique.

In this configuration, in order to communicate with circularly polarized waves, the support 1 on which the helical radiation element 2 is formed is pulled out.
Circular polarization is generated by feeding and exciting only this antenna. Further, since the support 1 is accommodated in the support 3 having the reverse rotation radiating element 4 and power is supplied to both antennas, both normal and reverse circularly polarized waves can be generated. Wave can be realized. The power supply is switched automatically or mechanically or electrically based on the operation of pulling out and storing the support 1.

FIG. 2 shows a second embodiment of the present invention. In this embodiment, the support 3 having the counter-rotating radiating element 4 is different from the support 1 having the normal-rotating radiating element 2. It is configured to be movable from the contracted state to the extended state in the axial direction. At this time, in order to communicate with circularly polarized waves, an antenna with an inner diameter D is pulled out, and only this antenna is excited to generate circularly polarized waves. By covering the antenna having the outer diameter d with the antenna having the inner diameter D, both normal and reverse circularly polarized waves can be generated, so that linearly polarized waves can be realized.

[0011]

As described above, according to the configuration and method of the present invention, a satellite in which axial mode circular polarization and vertical polarization can be transmitted and received by switching between expansion and contraction of an antenna, and a radio wave becomes weak in a distance. In communication using circularly polarized waves between a station and a ground station, an extended antenna is used, so in a device such as a portable communication device that uses an antenna close to a human body, circularly polarized waves are extended by the extended antenna. Since it is generated, good communication can be performed without being affected by the human body. In the reduced state, portability is good, and communication by linear polarization between ground stations
Since the antenna can be used in a reduced state, the operability is excellent.

[Brief description of the drawings]

FIGS. 1A and 1B are conceptual diagrams of a shared antenna showing a first embodiment of the present invention, wherein FIG.

FIGS. 2A and 2B are conceptual diagrams of a shared antenna according to a second embodiment of the present invention, in which FIG. 2A shows an extended state and FIG.

FIG. 3 is a schematic diagram showing the principle of the present invention.

FIG. 4 is a schematic diagram showing an embodiment of the prior art.

[Explanation of symbols]

 Reference Signs List 1 support of outer diameter d 2 radiating element 3 support of inner diameter D 4 radiating element 5 normal circular polarization (right circular polarization) 6 reverse circular polarization (left circular polarization) 7 linear polarization 8 cylinder Support

Claims (1)

(57) [Claims] 1. A first antenna in which a conductor is helically wound around a support having a relatively large diameter, and a first antenna in which a conductor is helically wound in a direction opposite to the first antenna around a support having a relatively small diameter. 2
An antenna, wherein the first antenna includes a second antenna and a reduced state;
One of the antenna and the second antenna is configured to be able to take both the extended state and the extended state moved in the antenna axis direction. A shared antenna characterized in that both antennas are fed to generate linearly polarized waves.