JPH0243803A - Parabolic antenna - Google Patents

Abstract

PURPOSE:To facilitate the maintenance in the main radiation direction and to surely prevent the reduction in the antenna gain by moving a primary feeder in response to the change in the main radiation direction so as to cancel the change in the said main radiation direction. CONSTITUTION:A displacement of a main reflecting mirror 1 provided to a support structure 5 is detected in displacement detectors 9a-9c, and when an arithmetic unit 11 detects the production of a fluctuation in the support angle of the main reflecting mirror 1 in the monitor state of displacement information outputted from the displacement detectors 9a-9c, the unit 11 operates the moving quantity of the primary feeder 3 so as to cancel the change in the main radiation direction of the main reflecting mirror 1. Then a driver 13 moves the position of the primary feeder 3 so as to cancel the movement calculated by the arithmetic unit 11 with respect to the main reflecting mirror 1. Thus, since the change in the main radiation direction is cancelled by moving the primary feeder to the main reflecting mirror 1 relatively, the maintenance in the main radiation direction is ensured and the reduction in the antenna gain is prevented.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a parabolic antenna.

(Prior Art) Parabolic antennas are widely used mainly in microwave communications because they have a simple structure and are inexpensive, in addition to providing extremely sharp directivity and high gain. The structure of the parabolic antenna 4 is one in which the main reflector 1 attached to the support structure 5 and the primary feeder 3 are directly coupled as shown in FIG. 8, and the main reflector 1 attached to the support structure 5 as shown in FIG. 1 and one in which the primary power feeder 3 is independently housed in the support structure 5. In addition, in FIG. 8 and FIG. 9, 7 is a repeater. In such a parabolic antenna, when radio waves are emitted from the primary feeder 3 during transmission, for example, since the primary feeder 3 is placed at the focal point of the paraboloid of the main reflector 1, The radio wave is reflected by the paraboloid of the main reflecting mirror 1, and a substantially plane wave is emitted in the direction of the aperture (main irradiation direction).

(Problems to be Solved by the Invention) Incidentally, in a parabolic antenna, it is important to maintain the main irradiation direction because fluctuations in the main irradiation direction cause a decrease in antenna gain. However, due to the shape of the main reflector 1, the main irradiation direction is likely to fluctuate due to the influence of external forces such as wind, rain, snow, etc. In particular, as seen in recent satellite communications and astronomical observation, the main reflector 1 has an extremely large parabolic antenna. Yes, it is noticeable. Specifically, the main reflecting mirror 1
If the angle formed by the support structure 5 and the supporting structure 5 (support angle) changes by, for example, φ, the main irradiation direction will also shift by the angle φ in the one shown in FIG. 8, and will shift by the angle 2φ in the one shown in FIG. .

For this reason, measures have been taken to maintain the main irradiation direction by driving the main reflecting mirror 1 in the opposite direction to the support structure 5 by an angle φ according to the amount of variation φ in the support angle. It requires large and complicated equipment.

The present invention has been made in view of the above, and an object of the present invention is to provide a parabolic antenna that facilitates maintenance of the main irradiation direction and ensures prevention of decrease in antenna gain.

[Configuration of the Invention (Means for Solving the Problems) In order to achieve the above object, the primary power feeder is designed to eliminate changes in the main irradiation direction in response to changes in the main irradiation direction due to fluctuations in the main reflecting mirror. The gist is to provide a moving means for moving the.

(Function) In the parabolic antenna according to the present invention, a means for moving the primary power feeder is provided, and the primary power feeder is moved according to a change in the main irradiation direction due to a change in the main reflecting mirror. It is designed to move so as to cancel out the .

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a diagram showing the configuration of a parabolic antenna according to a first embodiment of the present invention. In FIG. 1, the same members as in FIGS. 8 and 9 are designated by the same reference numerals, and detailed explanations thereof will be omitted.

In FIG. 1, 9a to 9C are displacement detectors that detect the displacement of the main reflecting mirror 1 provided on the support structure 5, and 11 is a displacement detector 11 based on the displacement information output from the displacement detectors 98 to 9C.
A calculation device 13 that calculates the amount of movement of the secondary power feeder 3 is a drive device that moves the position of the primary power feeder 3 relative to the main reflecting mirror 1 by the amount of movement calculated by the calculation device 11. Note that the displacement detectors 9a, 9b, 9c, arithmetic device 11, and drive device 13 constitute a moving means.

Next, the operation of this embodiment will be described as a second operation of the arithmetic unit 11.
This will be explained using FIGS. 4 to 4.

When the arithmetic unit 11 detects that the support angle of the main reflector 1 has changed by an angle φ due to some external force while monitoring the displacement information output from each of the displacement detectors 9a to 9C, the calculation device 11 detects that the support angle of the main reflector 1 has changed by an angle φ due to some external force. The amount of movement of the primary power feeder 3 that cancels out the change in the main irradiation direction of the primary power supply device 3 is calculated.

Specifically, the following calculations are performed.

As shown in FIG. 2, there are displacement detectors 9a, 9b, and 9c on a plane on the support structure 5, each having a U.

U,,U. Suppose that it is displaced by a certain amount and moves onto the plane M.

First, take the inner product of the unit normal vector n of the plane and the unit normal vector n of the plane M, and calculate the variation angle φ by φ-cos-I
(n-n-). Next, the focal length F of the main reflector 1
, the fluctuation angle φ, and the coefficient α are substituted into the following equation to obtain the movement amount d of the primary power feeder 3.

φ d=F tan α The coefficient α is the ratio F of the focal pressure NF and the diameter of the main reflecting mirror 1.
It is determined from the value of /D using the graph in FIG.

Once the amount of movement d is determined in this manner, the drive device 13 moves the primary power feeder 3 by d as shown in FIG. 4 in accordance with this result. Note that the direction of movement of the primary power feeder 3 is the direction of a vector A which is obtained by orthogonally projecting the unit normal vector n of the plane M onto the plane.

Therefore, according to this embodiment, the change in the main irradiation direction is
Since the secondary feeder 3 is moved relative to the main reflecting mirror 1 to compensate, the main irradiation direction can be reliably maintained, thereby preventing a decrease in antenna gain. In addition, compared to the conventional case in which the main body of the main reflector 1 is moved to eliminate changes in the main irradiation direction, it is only necessary to move the primary power feeder 3, which is smaller than the main reflector 1.
The configuration becomes easier.

In this embodiment, the main reflecting mirror 1 and the primary power feeder 3 are directly coupled (corresponding to FIG. 8), but as shown in FIG. The present invention is also applicable to a type in which the primary power feeder 3 is independently attached to the support structure 5 (corresponding to the above-mentioned FIG. 9). In the case of FIG. 5, if the variation angle of the support angle is φ, it is necessary to calculate the change in the main irradiation direction as 2φ.

FIG. 6 is a diagram showing the configuration of a parabolic antenna according to a second embodiment of the present invention. Its feature is that it forms a link mechanism that moves the primary power feeder 3 according to the fluctuations of the main reflecting mirror 1, and moves the primary power feeder 3 in the main reflection direction in conjunction with the fluctuations of the main reflecting mirror 1. The purpose is to move the object so as to offset the changes in the area. In addition, in FIG. 6, 15, 17, 19.
20 is a link that constitutes this link mechanism, 21.23° and 25.27 are sliding nodes, and 29 is an equivalent spring that represents the flexibility of the antenna. The same members as in Fig. 1 are given the same reference numerals and detailed. Further explanation will be omitted. In addition, links 15.17.
19.20 constitutes a transportation means.

Next, the operation of this embodiment will be explained with reference to FIG. 7, focusing on the operation of the link mechanism.

When the sliding nodes 21 and 23 on the main reflecting mirror 1 move by Ul due to a change in the support angle of the main reflecting mirror 1 due to an external force, etc., the L-shaped sunk 17 moves around the fulcrum 31 in conjunction with this. As a result, a movement amount of U2 is generated at the sliding node 25. With the movement of this L-shaped sink 17, a movement amount of U2 is also generated at the sliding node 27 via one second link, so the primary power feeder link 2
0 and is rotated about the sliding node 28 and moved by a distance.

In addition, as for the above-mentioned link mechanism, the movement amount UI at the sliding nodes 21 and 23 due to the fluctuation of the main reflecting mirror 1 and 1
The configuration is such that the following equation holds true between the movement iD of the next power feeder 3 and the movement iD of the next power feeder 3.

D-(Ai1・Ai4/Ai2・Ai3)・Ul Therefore, according to this embodiment as well, it is possible to securely maintain the main irradiation direction with a simple configuration and prevent a decrease in antenna gain.

[Effects of the Invention] As explained above, according to the present invention, a means for moving the primary power feeder is provided, and the primary power feeder is moved to the main irradiation direction according to the change in the main irradiation direction due to the fluctuation of the main reflecting mirror. The main irradiation direction can be easily maintained by moving the antenna so as to offset the change in direction, thereby reliably preventing a decrease in antenna gain.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a first embodiment of the present invention, FIGS. 2 to 4 are diagrams for explaining the first embodiment, and FIG. 5 is a diagram showing a first embodiment of the present invention.
FIG. 6 is a diagram showing a second embodiment of the present invention, FIG. 7 is a diagram for explaining the embodiment of FIG. 2, FIGS. 8 and 9 1 is a diagram showing a conventional example. 1... Main reflector 3... Primary power feeder 5...
Support structure 7...Relayers 9a, 9b, 9c...
・Displacement detector 11... Arithmetic device 13... Drive device 15.1
7, 19.20... Link Figure 1 Agent Patent Attorney Yasuo Miyoshi Figure 2 F/D Figure 3 Figure 4 Figure 7 Figure 8 Figure 6 Figure 9

Claims (1)

[Claims] A parabolic antenna characterized by comprising a moving means for moving a primary power feeder so as to eliminate a change in the main irradiation direction in response to a change in the main irradiation direction due to a change in the main reflecting mirror.