JPS5892106A - Multibeam antenna - Google Patents

Abstract

PURPOSE:To obtain a multibeam antenna with less gain reduction and increase in the side lobe level, by arranging a reflecting mirror so that incident waves from different directions can be converged to the center of phase of a plurality of primary radiators via the main reflecting mirror and the sub-reflecting mirror. CONSTITUTION:Three different waves toward three directions are applied from horns 2a, 2b, 2c to an axuiliary reflection mirror 6a. A main reflection mirror 4 and a sub-reflection mirror 5 are secondary curved-surface of revolution, or low side lobe type high efficiency correction curved surface. The curved-suface of auxiliary reflecting mirors 6a-6c can be determined from the conditions of electromagnetic wave collection taking the hase of a pluralty of horns as a center and of constant optical length. A large beam deflection range is split into each block, the main reflecting mirror and the subreflecting mirror are used in common, and a multibeam antenna with excellent performance can be obtained by providing the auxiliary reflecting mirrors corresponding to each block.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a reflective challenge type multibeam antenna having a plurality of primary radiators.

Conventional antenna of this kind Fi@1 As shown in Figure.

Parabolic reflection - (11, and multiple primary radiators (2
It was composed of 1. Here, the -order radiator (21) is placed near the focal point F of the parabola (1:).

As the primary radiator (21) moves away from this focal point F, the beam deflection increases; The drawback was that it caused performance deterioration such as an increase in rope level.This large beam deflection is required for the antenna onboard the satellite, and this is explained using Figure 2.Satellite and Earth (Each point on 31, A , B, C, etc.

It will be within a range of about 20' as seen from the satellite. In order to efficiently irradiate each of these points, the beam width toward each point is required to be narrow. Therefore, the beam deflection angle/beam width is lO~20.

On the other hand, in the case of a parabola, this ratio is about 4.

This results in a gain reduction of 1 dB, making it difficult to use the method shown in FIG.

Here, each point of @2 corresponds to each block, i.e. (A, B,
Note that the C), (D, E, F) O and (G, H) K portions are larel, and in order to eliminate the above drawbacks in this invention, they are in the form of three bells, and the following 1. This will be explained in detail using drawings.

FIG. 3 shows an embodiment of the invention. (4) is a main reflecting arm, (51 is a sub-reflector, and (61 is an auxiliary reflector).

(2) is the same as in FIG. 1, and is a plurality of primary radiators.

Here, an antenna system corresponding to the case of Figure @2, that is, the case of dividing into three blocks is shown. The beam heading towards the block (＾, B, C) is auxiliary reflection @ (6
m) 1r- through -order radiation 6 (2m, 2b, 2e
), and the blocks (D, E, F), (G
H) K is also 11. Main reflector (4), secondary reflector &! +51 can be a rotating quadratic surface, a low sidelobe curve, or a high-efficiency modified surface, just a -order radiator (2), auxiliary reflection fi161t! It is necessary to make the size larger to prevent the radio waves from spilling over. The auxiliary reflector (610 curved surface can be determined from the condition that the optical path length is constant so that the radio waves are focused at each focal point *'Is F2mF3.A primary radiator for each valley block is placed near these focal points.For each block. By setting the deflection beam deflection to several beam widths, it is possible to prevent a decrease in gain and an increase in the side lobe level, and it is possible to obtain a multi-beam antenna with little overall performance deterioration.

In the case of one or more, a reflecting mirror is provided between the primary radiator and the sub-reflecting mirror to serve as an auxiliary reflecting mirror, but the same effect can be obtained by replacing the 0-reflecting mirror with a dielectric lens.

As described above, according to the present invention, a large beam deflection range is divided into blocks, and the main reflector and sub-reflector 'd
f,? By providing a shared auxiliary reflector tube for each block, it has the advantage of being a multi-beam antenna with little loss of gain and little increase in sidelobe level.・

[Brief explanation of the drawing]

Figure $1 is a schematic configuration diagram of a conventional multi-beam antenna, Figure 2 is a diagram explaining the present invention, and Figure @3 is a schematic configuration diagram of an embodiment of the present invention. In the figure, (21 is the primary radiator, (4) II'i main reflector, +51t; i sub-reflector, (6: is the auxiliary reflector. In the figure, the same or equivalent parts are given the same reference numerals. It shows. 寥 1 Ha'%Z shame

Claims (1)

[Claims] (Main reflecting mirror and auxiliary reflecting mirror consisting of an 11-turn quadratic curved surface. Consisting of a plurality of auxiliary reflecting lines, and a plurality of primary radiators corresponding to each of the plurality of auxiliary reflecting mirrors. In a multi-beam antenna. The plane beams incident from different directions are the main reflections. After passing through the secondary radiation theory, the curved surface of each auxiliary reflector is adjusted to the optical path length so that the radio waves are focused on the phase center of multiple primary radiators. (21) A multi-beam antenna characterized in that the auxiliary reflecting mirror is a dielectric lens.