JPH0236604A - Antenna system - Google Patents

Abstract

PURPOSE:To eliminate an undesired radiation wave and to improve the wide angle radiation characteristic by mounting a radio wave absorbing body of a curved face forming a torus group over the radio channel of an antenna system. CONSTITUTION:The radio wave absorbing body 5 having a curved face whose cut face perpendicular to the beam axis form a torus group is fit along the peripheral of the beam in a zone where a beam radiated from a feeding horn 4 is radiated from the aperture of a main reflecting mirror 1. Thus, a refracted wave contributing to an undesired radiation from an edge A1 of a focus reflecting mirror 3, an edge B1 of a sub reflecting mirror 2 and an edge C1 of a main reflection mirror 1 is eliminated by using the radio wave absorbing body 5. Thus, the wide angle radiation characteristic of the antenna system is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an improvement in an antenna device used in a microwave terrestrial relay line or the like.

rConventional technology] Conventionally, the antenna device in this building has the following features as shown in Figure 2.
It consisted of a main reflector (11), a sub-reflector (21), a focusing reflector (3), and a feeding horn (4).

Each mirror surface is an asymmetric ψ surface, and the sub-reflection mirror (2) directs the radio waves from the phase center F1 of the feeding horn (4) to the focal point F,
It is an ellipsoidal casting drawn by.

Most of the radio waves emitted from the phase center F, as shown by the dotted line in the figure, are radiated toward the front of the antenna through focused reflection m(3+, sub-reflector (2), main reflector +ll'i, and form the main beam gold). do.

[Problem to be solved by the invention]

In this antenna device, some of the radio waves from one point F+ are reflected at the edges A+A, ... of the focusing reflector (3), edges B+, Bt, etc. of the sub-reflector (2), and then the main reflection. When facing the mirror (11 edges C1, C!...), diffraction occurs at these points, and unnecessary radiation occurs in a direction far away from the front direction, as shown by the solid line in Figure 1, that is, the wide-angle radiation characteristics of the antenna device. There was a problem of deterioration.

This invention was made to solve all the problems mentioned above, and is characterized by the shape and arrangement of the radio wave absorber.
The purpose is to improve wide-angle radiation characteristics.

1. Means for Solving the Problems] The antenna device according to the present invention has a beam emitted from a feeding horn that is emitted from a main reflector aperture in a region where the beam is radiated from the main reflector aperture. It is equipped with a curved radio wave absorber as shown in A whose cut surface is a ring group.

[Effect]

This invention (1) As mentioned above, the antenna device is equipped with a curved radio wave convergence device whose cut direction perpendicular to the beam axis forms a ring group along the outer periphery of the beam. Because of 5 each reflection from the edge scattering gold can be removed, wide-angle radiation characteristics can make the sound better.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The entire drawings of an embodiment of the present invention will be described below. 1st
In the figure, fil , F2+ , 13+ ,
(4+ is the same as that shown in Fig. 2, RQ point F+ is the phase center of the feeding horn fl+, and the focused flux reflection casting (
Even the focus of 2) is Δ. In addition, point F is the confocal point of the sub-reflector (21) and the main reflector (1+), and the mirror system is configured so that the radio waves are focused at point F.This point F,
, find the smallest possible circle that does not interfere with the radio waves forming the main beam toward the main reflecting mirror (11) and find Δ
Be able to do that. As you move away from point F, the radio wave components that form the main beam spread out, so the radius of the circle that does not interfere becomes larger Δ. Attach a radio wave absorber around the circle group mentioned above.
In this case, a curved radio wave absorber (
5). Such a radio wave absorber (5) can reduce the edges A+, Al,... of the focused reflection Sakaki (3), the edges B+, Bt,... of the sub-reflector (2), and the edges of the main reflection Ifl. It is possible to remove unnecessary radiation from the antennas C1, C, . . . and improve the wide-angle radiation characteristics of the antenna device.

Note that 1 and above describe the case where the beam convergence point is one, but the present invention is not limited to this, and there may be a plurality of convergence points. However, the present invention is not limited to this, and any number of rings may be used.] As described above, according to the present invention, one ring group and one ring group can be formed over the entire radio wave path of the antenna device. Since it is equipped with a radio wave absorbing bar with a curved surface, it has the effect of removing unnecessary radiation waves and improving wide-angle radiation characteristics.

[Brief explanation of the drawing]

FIG. 1 shows an antenna device according to an embodiment of the present invention, and FIG. 2 shows a conventional antenna device. In the figure, (11 is a main reflecting mirror, (2) is a sub-reflecting mirror, (3) is a focusing reflecting mirror, (4) is a feeding bone, and (5) is a curved radio wave absorber. In the diagram, the same or corresponding parts are indicated by the same reference numeral.

Claims (1)

[Claims] In an antenna device in which one or more reflecting mirrors are present between the feeding horn and the main reflecting mirror, the beam emitted from the feeding horn is radiated along the outer circumference of the beam in the range until it is radiated from the main reflecting mirror aperture. What is claimed is: 1. An antenna device comprising: a curved radio wave absorber whose cross section perpendicular to the beam axis forms a ring group;