JPH066576Y2 - Sub-reflector support mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an improvement of a sub-reflector support mechanism of an antenna having a sub-reflector like a Cassegrain antenna and having a variable depression angle.

[Conventional technology]

Conventionally, in an antenna having a sub-reflecting mirror such as a Cassegrain antenna, the sub-reflecting mirror is supported by a supporting column at the front position of the main reflecting mirror. Usually, as this support mechanism,
It has a structure that is fixedly attached using screws, etc.
This is also the case for an antenna with a variable depression / elevation angle in which the antenna can change its angle in the vertical direction.

[Problems to be solved by the invention]

In such a mechanism, since the support column supports the sub-reflector while being elastically deformed by the weight of the sub-reflector and the weight of the support column itself, the action of gravity is caused by the change in the elevation angle of the antenna. When the direction changes, the amount of elastic deformation of the support column also changes, which causes the position of the sub-reflecting mirror fixed to the support column to move.

Such lateral positional deviation of the sub-reflecting mirror with respect to the antenna radiation axis significantly impairs the symmetry of the side rope level of the antenna radiation pattern, which is a very serious problem in terms of antenna characteristics.

An object of the present invention is to provide a sub-reflector support mechanism capable of automatically correcting the positional deviation of the sub-reflector due to a change in the elevation angle of the antenna and keeping the antenna characteristics in an optimum state at all times. .

[Means for solving problems]

The sub-reflector support mechanism of the present invention includes a sub-reflector supported by a support column of the antenna and movable laterally with respect to the radiation axis of the antenna, and a part of the sub-reflector having an eccentric weight to change the elevation angle of the antenna. And a cylindrical cam that is rotated by the gear and has a guide groove provided on its peripheral surface and engaged with the sub-reflecting mirror, and the guide groove of the cylindrical cam is used for changing the elevation angle of the antenna. With a shape corresponding to the elastic deformation characteristics of the supporting pillars involved, the sub-reflecting mirror is moved by a predetermined amount by the rotation of the cylindrical cam due to the change in the elevation angle of the antenna, thereby correcting the lateral movement of the sub-reflecting mirror. There is.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a partially cutaway front view of an embodiment of the present invention, FIG. 2 is a left side view of the same, and FIG. 3 is a rear view thereof. These figures show the Cassegrain in the state of facing the zenith. The vicinity of the sub-reflector mounting portion of the antenna is shown.

In these figures, reference numeral 1 denotes a support pillar having four pillars formed in a pyramid shape, which is arranged in front of the main reflecting mirror (not shown). A base 2 for supporting the sub-reflecting mirror 3 is fixedly provided at the tip of the support column 1.
A guide hole 4 is provided near the center of the base 2 for sliding the sub-reflecting mirror 3 laterally with respect to the radiation axis of the antenna.

The sub-reflecting mirror 3 has a styder portion 5 fitted in the guide hole 4 on the back surface thereof, and the slider portion 5 is integrally formed with a guide pin 6 protruding rearward. At the position behind the guide pin 6, a cylindrical cam 7 axially supported along the guide hole 4 and rotatably supported by the base 2 is disposed, and the tip end portion of the guide pin 6 is disposed. Is inserted into the guide groove 8 provided on the side surface of the cylindrical cam 7 so as to be slidable in the guide groove 8 without any significant play.

A bevel-shaped small gear 9 is attached to a part of the cylindrical cam 7, and is meshed with a bevel-shaped large gear 10. The bevel gear 10 is rotatably supported by a shaft, and an eccentric weight 11 is attached to a part of the circumference thereof.

In the sub-reflecting mirror support mechanism having such a structure, when the antenna rotates at an elevation angle or a depression angle, the support column 1 and the base 2 are rotated together with the antenna.
Therefore, the direction of gravity with respect to the support mechanism is changed, and the large bevel gear 10 is rotated in the direction in which the eccentric weight 11 is oriented in the direction of gravity. The cylindrical cam 7 is rotated by the rotation of the large bevel gear 10 via the small bevel gear 9, and the guide pin 8 is laterally moved by the guide groove 8 on the side surface, so that the slider portion is moved in the guide hole 4. 5 and the sub-reflecting mirror 3 are moved.

The movement amount of the sub-reflecting mirror 3 is determined by the shape of the guide groove 8 and the rotation amount of the cylindrical cam 7, that is, the rotation amount of the large bevel gear 10, and the large bevel gear 10 corresponds to the change in the elevation angle of the antenna. As a result, it is determined according to the angle of elevation and depression of the antenna. Therefore, by setting the guide groove 8 of the cylindrical cam 7 as a correction curve in accordance with the elastic deformation characteristics of the support column 1 at each depression / elevation angle, the sub-reflecting mirror 3 is moved to a position corresponding to a change in the depression / elevation angle of the antenna and is supported. It is possible to correct the lateral movement of the sub-reflecting mirror due to the change in the elastic deformation amount of the pillar 1 or the like. This correction can be continuously performed with respect to the depression and elevation angle of the antenna.

Further, by extending the length of the cylindrical cam 7, the same correction can be performed even when the elevation angle is lowered to the opposite side beyond the depression angle direction or the zenith direction. On the other hand, when the depression / elevation angle rotation range is narrow, it is sufficient to set the cam groove to a length corresponding to it.

In addition, use a bearing to reduce friction in each sliding part, or use a part of the bevel gear as a thick wall instead of an eccentric weight, and do not directly fix the guide pin to the sub-reflecting mirror. Various modifications are possible, such as amplifying and converting the moving force due to the moving force of the sub-reflecting mirror via the link mechanism.

[Effect of device]

As described above, according to the present invention, the cylindrical cam is rotated by the gear partly having an eccentric weight and rotated in accordance with the change in the elevation angle of the antenna, and the sub-reflector is moved laterally by the cylindrical cam. Since it is configured to operate, it is possible to automatically correct the movement amount of the sub-reflecting mirror in response to the change in the elevation angle of the antenna, which does not require a power source or an electric control circuit. It is possible to always set the sub-reflecting mirror at the optimum position, which is very effective in improving the characteristics of the antenna.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of the present invention, and FIG.
FIG. 3 is a left side view of the figure, and FIG. 3 is a rear view of FIG. 1 ... Support pillar, 2 ... Base, 3 ... Sub-reflector, 4 ...
Guide hole, 5 ... Slider part, 6 ... Guide pin, 7 ...
… Cylindrical cam, 8 …… Guide groove, 9 …… Bevel gear, 10…
… Umbrella large gear, 11 …… Eccentric weight.

Claims (1)

[Scope of utility model registration request] 1. A sub-reflecting mirror which is supported by a supporting column of an antenna and is movable laterally with respect to the radiation axis of the antenna, and a sub-reflecting mirror part of which has an eccentric weight and which is rotated in accordance with a change in the elevation angle of the antenna. Gear, and a cylindrical cam which is rotated by the gear and provided on its peripheral surface to guide groove is engaged with the sub-reflecting mirror. The guide groove of the cylindrical cam is the support column according to the elevation angle of the antenna. The shape corresponding to the elastic deformation characteristics of
A sub-reflecting mirror supporting mechanism, characterized in that the sub-reflecting mirror can be moved by a predetermined amount by rotation of a cylindrical cam accompanying a change in the elevation angle of the antenna.