JPS6298803A - Movable beam antenna system - Google Patents

Abstract

PURPOSE:To make a beam movable by a small gain drop extending over a wide range, by placing a primary radiator in two points, respectively, which are symmetrical with regard to a center section of a specular system, and connecting these radiators to a transmitter-receiver through a switch. CONSTITUTION:The force of a gear 6 which has been rotated by a motor, etc., is transmitted to a sub-reflection mirror 2, and the sub-reflection mirror 2 rotates centering around a fixed point. In this case, an electromagnetic wave which has been radiated from a primary radiator 3a or 3b is reflected by the sub-reflection mirror 2 and a main reflection mirror 1, and radiated in the direction corresponding to a rotational angle of the sub-reflection mirror 2. Arrangement positions F1, F2 of the respective primary radiators 3a, 3b are deflected from a focus F0, therefore, a direction in which the antenna gain becomes maximum is shifted in other direction. By switching suitably a switch 5, a beam direction which can be covered expands with a high gain.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a movable beam antenna device that can change the beam radiation direction by driving a sub-reflector.

[Conventional technology]

FIG. 3 is a sectional view of a conventional movable beam antenna device disclosed in, for example, Patent Application Publication No. 51-24217. In FIG. 9, (1) is a main reflector, (2) is a sub-reflector,
(3) is a -order radiator placed at point FQ, (4) is a transmitter/receiver, and 61 is a gear that is rotated by a motor or the like. In addition, the main reflecting mirror (1) and the sub-reflecting mirror (2) are at point F.
Through Q 1) It is plane symmetrical with respect to the plane (center cross section) orthogonal to the Y axis.

Next, the operation will be explained. The force of the gear (61) rotated by a motor etc. is transmitted to the sub-reflector (2), and the sub-reflector (2) rotates around a fixed point.As a result, the electromagnetic waves radiated from the -order radiator (3) is the sub-reflector (2).

It is reflected by the main reflecting mirror fil and radiated in a direction according to the rotation angle of the sub-reflecting mirror (2). At this time, if the shape of the mirror system is determined as shown in Patent Application Publication No. 51-24217, when the beam direction θ is θ, the point FQ
The light rays emitted from the aperture hit the aperture as a plane wave.

As a result, as shown in FIG. 4, a so-called bifocal antenna can be realized in which the antenna gain is maximum at θ=−θm.

Therefore, the beam can be moved over a wider range with a slightly lower gain than when the mirror system is composed of a normal quadratic curved mirror. Further, θm is a design parameter, which can be arbitrarily selected.9 For example, when moving the beam over a wider range, θme may be selected to be large.

[Problem that the invention seeks to solve]

However, as seen in Figure 4, the front direction.

In other words, the gain when θ=O is lower than the gain when θ=±θm, and the degree of this is more pronounced as θm is chosen larger. As a result, when trying to move the beam over a certain range, there are restrictions on how to select θm, and a large beam movement cannot be achieved with a small gain reduction.

The present invention has been made to solve the above-mentioned problems, and its object is to provide a movable beam antenna device that can move the beam over a wider range with a slight decrease in gain.

[Means for solving problems]

The movable beam antenna device according to the present invention is the bifocal antenna shown in FIG. 3, in which primary radiators are arranged at 42 points symmetrically with respect to the central cross section of the mirror system, and these are connected to a transmitter/receiver via a switch. It is.

[Effect]

The movable beam antenna device in this invention is:

By appropriately switching the horn connected to the transmitter/receiver with a switch, the beam can be moved over a wide range with little loss of gain.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, CI) is the main reflector, [2) is the sub-reflector,
(3a) and (3b) are the primary radiators arranged symmetrically on the center cross section of the mirror system, respectively, and (4) are the transmitting and receiving f.
fi, (5) connects the transceiver (4) to the -order radiator (3a)
Alternatively, the switch connected to (3b) and (6) are gears that are rotated by a motor or the like.

Next, the operation will be explained. Similar to the conventional movable beam antenna device, the gear (6+ force) rotated by a motor etc. is transmitted to the sub-reflector (2), and as a result the sub-reflector (2)
rotates around a fixed point. At this time, the −order radiator (3a
) or (3b), the electromagnetic waves emitted from the sub-reflector (2
), reflected by the main reflecting mirror (1).

The light is emitted in a direction according to the rotation angle of the sub-reflector (2).

Figure 2 shows the change in antenna gain with respect to the beam direction at that time.
When connected to the -order radiator (3a), FIG. 2(b) shows the case where it is always connected to the primary radiator (6b).

Since the arrangement positions F1 + F2 of each of the -order radiators (3a) and (3b) are deviated from the focal point FQ, the directions in which the antenna gain is maximum are in different directions compared to Fig. 4. It's off. FIG. 2(C) shows these superimposed, and by appropriately switching the switch (5), a gain as shown by the solid line can be obtained. In other words, the direction in which the antenna gain is maximized is widened by the change in beam direction caused by moving the primary radiator position from FQ to 71 and F2,
A wide range of beam directions can be covered with high gain.

In the above embodiment, the force configuration was explained so that the sub-reflector acts to block the beam radiated from the main reflector, but it is also possible to use a bifocal antenna of the Hiko offset type, which has various effects on blocking. The same effect as in the above embodiment can be obtained.

Further, in the above embodiment, a case has been described in which the sub-reflector is driven by a motor and a gear, but the present invention is not limited to this (the same effect can be achieved by using any driving device).

〔Effect of the invention〕

As described above, according to the present invention, the primary radiators that feed the sub-reflector-driven bifocal antenna are arranged at two points F'1 and '72, respectively, which are distant from the focal point FQ.

Since the primary radiator used is changed over by a switch, the beam can be moved over a wider range with low gain reduction.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a movable beam antenna device according to an embodiment of the present invention, FIG. 2 is a diagram for explaining the invention in detail, and FIG. 3 is a cross-sectional view showing a movable beam antenna device according to an embodiment of the present invention. A cross-sectional view showing a dual point antenna device,
FIG. 4 is a diagram for explaining the principle of a conventional movable beam antenna device. (1) is the main reflector, (2) is the sub-reflector, and (3) is the -order radiator. (4) is a transmitter/receiver i, (51 is a switch, and (61 is a gear.) In FIG. 9, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A mirror system in which a main reflecting mirror and a sub-reflecting mirror are configured symmetrically with respect to the same plane (the central cross section), and a primary radiator arranged at points F_1 and F_2, respectively, symmetrical with respect to the central cross section. In a movable beam antenna device comprising a device for rotating a sub-reflector around an axis in the central cross section, when the sub-reflector is rotated around the rotation axis and the rotation angle is φ, the center The mirror surface system is determined so that the wavefront after the ray emitted from the fixed point F_0 in the cross section is reflected in the order of the sub-reflector and the main reflector becomes a plane at the two rotation angles of φ=±φm, and further, A movable beam antenna device, characterized in that the two primary radiators are connected to a transmitter via a switch.