JPH04145702A - Dual reflecting mirror antenna - Google Patents

Abstract

PURPOSE:To make radial dimension of a sub reflecting mirror by arranging the sub reflecting mirror to a plane wave region of a focus beam transmission line. CONSTITUTION:A focus F1A at a side of a sub reflecting mirror of a focus beam type primary radiator 3A is arranged to a position of the sub reflecting mirror 2A. Thus, the sub reflecting mirror 2A is energized at a plan wave region forming a plane wave front being a beam waist of a focus beam transmission line and the sub reflecting mirror with a smaller diameter is adopted. That is, even when a sub reflecting mirror with a smaller diameter is employed, the design of suppressing the leakage power from the sub reflecting mirror 2A to be a sufficiently low value is attained. Furthermore, the sub reflecting mirror is configurated by selecting parameters of a focus of a main reflecting mirror 1 and a radius of curvature of a focus reflecting mirror used for the primary radiator 3A so that the focus F1A at the side of the sub reflecting mirror of the primary radiator 3A and the position of the sub reflecting mirror 2A are almost made coincident.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a double-reflector antenna, and more particularly, to a double-reflector antenna in which paraxial sidelobe characteristics are improved by employing a sub-reflector with a small diameter.

[Conventional technology]

Recently, with the increasing demand for communications using satellites, requirements for the sidelobe characteristics of earth station antennas for satellite communications have become stricter, from the standpoint of effectively utilizing the geostationary orbit of satellites, which is humanity's limited common asset. ing. As many satellites come to be placed close to each other in geostationary orbit, each earth station that utilizes these satellites is required to install antennas that suppress sidelobe levels to lower levels in order to reduce interference between lines caused by nearby satellites. It is required to have the following.

In general, the sidelobe characteristics of antennas are broadly classified into paraxial sidelobe characteristics and wide-angle sidelobe characteristics, but in satellite communication earth station antennas, from the perspective of reducing interference between adjacent satellites in geostationary orbit, , it is important to improve the paraxial sidelobe characteristics.

Conventionally, this type of double-reflector antenna, as shown in the block diagram of FIG. 2nd side focal point F
1 is composed of a focused beam-type radiation beam placed between a main reflector 1 and a sub-reflector 2; In this way, a double reflector antenna with a focused beam feed using the focused beam propagation path as the primary radiator 3 has an azimuth angle of 5 around A29.
Since communication equipment can be installed at the floor position depending on the rotation and elevation angle rotation around the EL axis, it is effective for easy daily use and maintenance and for expanding communication equipment.

Next, the configuration and operation of the focused beam type primary radiator 3 will be explained with reference to FIG. The microwaves supplied to the communication equipment 14 for transmission are emitted by the iphone 11 having a focal point F2, which passes through the reflector plate m12A, the reflector surface 12B, the reflector surface 13A, and the reverse plate surface 13B in sequence. After the beam is focused at the focal point F1 of the sub-reflector 2, it is electrified into a beam by the sub-reflector 2. In the case of reception as well, the spherical waves of the main reflecting mirror 1 are beam-focused and reflected by the solid reflecting mirror 2, and the microwaves are directed towards the communication equipment 14 in the opposite C direction to the above-mentioned direction and receive the microwaves.

Here, since the sub-reflector-side focal point F1 of the -order radiator 3 is placed between the main reflector 1 and the sub-reflector 2, the 5th sub-reflector 2 has a spherical spread wavefront of the focused beam transmission path. As shown in the beam characteristic diagram of the focused beam transmission path in FIG. It is necessary to adopt a large sub-reflector. The paraxial sidelobe characteristics of a double reflector antenna with such conditions are:
As shown in the sidelobe characteristic diagram of FIG. 3, it depends on the diameter of the sub-reflector that blocks the center of the main reflector aperture. In other words, the effect of the sub-reflector diameter on the paraxial side-lobe characteristics is that when R is the ratio of the sub-reflector diameter (numerator) to the main reflector diameter (denominator), the ratio of R becomes larger. This increased the peak level of the sidelobe and degraded the paraxial sidelobe characteristics of the antenna.

[Problem to be solved by the invention]

In the conventional focused beam-fed multi-reflector antenna described above, the sub-reflector is placed in the area of the spherical spreading wavefront of the focused beam transmission path, so it is necessary to use a sub-reflector with a large diameter. Additionally, there is a drawback in that there is a limit to the improvement of paraxial sidelobe characteristics in the design of double-reflector antennas.

[Means to solve the problem]

The double-reflector antenna of the present invention is a double-reflector antenna having a main reflector, a sub-reflector, and a focused beam type primary radiator. It is placed in the position of

〔Example〕

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

FIG. 1 is a block diagram of an embodiment of the present invention. The embodiment shown in FIG. 1 has a main reflecting mirror 1 with a concave reverse slope, a sub-reflecting mirror 2 with a convex reflecting surface, and a focusing lens in which the focal point FIA on the sub-reflecting mirror side is placed at the position of the sub-reflecting mirror 2A. It is composed of a beam type primary radiator 3A. The configuration inside the focused beam type primary radiator 3A is the same as the conventional bone 1-1 and reflector surfaces 12A, 12B, and 13A, except that the position of the focal point FIA is changed.

The configuration is the same as that of 13B.

Next, the operation of this embodiment will be explained. As mentioned above, since the sub-reflector side focal point FIA of the -order radiator 3A is arranged at the position of the sub-reflector 2A, the focused beam in FIG. 2, which is a common explanatory diagram of the conventional example and this embodiment, is As shown in the beam characteristic diagram of the transmission path, the two sub-reflectors will be fed to the plane wave wP region which presents a planar wavefront, which is the beam waist of the focused beam transmission path, and the sub-reflector with a small diameter A mirror can be used. In other words, even if a sub-reflector with a small diameter is used, will there be leakage from the sub-reflector 2A? ! ! ! It is possible to design the power consumption to a sufficiently low value. In addition, in the configuration of the double-reflector antenna of the present invention, the parameters of the focal length of the main reflector and the radius of curvature of the focusing reflector used for the primary radiator are set to the focal length FIA on the side of the sub-reflector of the -order radiator 3A. This can be achieved by selecting the positions of the sub-reflecting mirrors 2A so that they almost match. In this way, the double-reflector antenna of this embodiment can use a sub-reflector with a small diameter, so it can produce good paraxial sidelobes that suppress sidelobe deterioration due to blocking of the main reflector aperture center radiation part. characteristics can be realized.

〔Effect of the invention〕

In the focused beam feeding type multi-reflector antenna of the present invention, the diameter of the sub-reflector can be reduced by arranging the sub-reflector in the plane wave region of the focused beam transmission path. effective.

Therefore, it is possible to provide a multi-reflector antenna having good sidelobe characteristics with a low paraxial sidelobe level.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an embodiment of the present invention, Fig. 2 is an explanatory diagram of an embodiment of the present invention and a conventional system, and Fig. 3 is a paraxial side diagram illustrating the improvement effect of the present invention over the conventional example. FIG. 4, which is an explanatory diagram of the lobe level, is a configuration diagram of a conventional double-reflector antenna. 1... Main reflecting mirror, 2, 2A... Sub-reflecting mirror, 3, 3A
,... Focused beam type primary radiator, 11... Horn, 1
2A, 12B, 13A, 13B...reflector surface, 14.
...Communication equipment, Fl, F2. FIA -- Focus of focused beam type primary radiator, Ws -- Spherical wave, W, -- Plane wave.

Claims (1)

[Claims] 1. In a multi-reflector antenna having a main reflector, a sub-reflector, and a focused beam type primary radiator, the focus on the sub-reflector side of the focused beam type primary radiator is set to the focus of the sub-reflector side of the focused beam type primary radiator. A multi-reflector antenna characterized by being placed at the position of. 2. When the wavefront of the radiation beam of the focused beam type primary radiator transitions from a plane wave region to a spherical wave region, the position of the sub-reflector is selected within the range of the plane wave region. Item 1. The double-reflector antenna according to item 1.