JP2614789B2 - Yagi 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 Yagi antenna capable of easily switching the direction of directivity.

[0002]

2. Description of the Related Art Yagi antennas having a unidirectional directivity with a simple structure in which a parasitic element is arranged before and after a single feed element are widely used as high-gain antennas in specific communication lines. I have. Also, by rotating the antenna itself, it is used to know the approximate direction of the radio wave emission source from its maximum gain direction.

[0003]

In order to determine the direction of arrival of a radio wave using a conventional Yagi antenna, it is necessary to rotate the antenna itself over the entire circumference. Operation is difficult and not practical. In addition, there is a problem that the half value angle of directivity is large and accurate azimuth measurement is impossible.

The present invention has been made to solve the above-described problems, and has as its object to obtain an antenna element required for configuring an antenna system capable of electronically rotating its directivity.

[0005]

As means for electronically rotating the directivity of the Yagi antenna, the dimensions of the parasitic element to be constituted are assisted equivalently to correspond to the director and the reflector. The device is electronically added and changed.

[0006]

Since the size of the parasitic element can be changed electronically alternately, the direction of directivity can be switched back and forth.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an antenna according to the present invention. Reference numeral 1 denotes a parasitic element disposed at a predetermined interval before and after a feed element 2. As shown in FIG. 2, the parasitic element is configured such that an auxiliary element 3 which is electrically insulated and added to the tip thereof can be turned on and off by the control element 4. As shown in FIG. 2, the control elements 4 are attached to the parasitic elements 3 installed before and after the feed element 2 so as to conduct in opposite directions. Assuming that a positive voltage is applied to these through the conducting wire 5, one of them operates as a reflector with the auxiliary element 3 added thereto, and the other operates as a director since the auxiliary element 3 is not added. Therefore, this antenna has directivity in the direction of the element to which no auxiliary element is added. Conversely, if a negative voltage is applied, the element to which the auxiliary element 3 is added is reversed, so that the directivity is also reversed. By switching the polarity of the voltage applied to each parasitic element as described above, a Yagi antenna capable of reversing the directivity can be configured.

Although the method of directly controlling the control element 4 with positive and negative voltages using a conductor has been described above, when a system is constructed using a plurality of antennas, the directivity is disturbed by the conductor for control. You. To avoid this, the above object can also be achieved by incorporating a battery in the parasitic element and controlling the control element 4 by an optical signal via an optical fiber irrelevant to an electric field.

FIG. 3 shows an embodiment in which a plurality of antennas having the above configuration are arranged symmetrically with respect to a plurality of points. Two sets of antennas are arranged orthogonally. Reference numeral 5 denotes an antenna switch for switching the outputs of the two feed elements in synchronization with the parasitic element 3. Since the control signal controls the control element 4 and the antenna switch 6 in a specific order, the directivity of the antenna system can be changed by 90 degrees in accordance with the sequence of the control signal.

[0010]

As described above, the Yagi antenna according to the present invention is arranged at a plurality of set points, and the dimensions of the parasitic element of each antenna are sequentially electronically controlled. An equivalent effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a Yagi antenna according to the present invention.

FIG. 2 is a diagram showing a structure of a parasitic element constituting a Yagi antenna according to the present invention.

FIG. 3 is a diagram illustrating a Yagi antenna in which a plurality of Yagi antennas according to the present invention are arranged at multiple points.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Parasitic element 2 Feed element 3 Auxiliary element 4 Control element 5 Conductor 6 Antenna switch

Claims (3)

(57) [Claims] An auxiliary element which acts as a reflector over its entire length is insulated and added to the tip of an element which acts as a director with a parasitic element, and its connection is interrupted by a control element. A Yagi antenna characterized in that the direction of the directivity is switched back and forth by doing so. 2. The Yagi antenna according to claim 1, wherein the control element is controlled by an optical signal via an optical fiber. 3. The method according to claim 1, wherein the plurality of points are arranged so that their directivities are sequentially switched by a control signal, so that an effect equivalent to rotating an antenna is obtained. The Yagi antenna according to claim 2.