RU2420841C1 - Axially symmetric double-reflector antenna - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: double-reflector antenna consists of an emitter, an axially symmetric main reflector, a primary radiator and a conical screen around the edge of the primary reflector, where the axis of the cone coincides with the axial axis of the antenna. Said screen is open on the top part of the edge of the primary reflector.

EFFECT: high noise immunity and high noise Q-factor of the reception system with an axially symmetric double-reflector antenna by reducing heat radiation of the ambient medium and hence antenna noise temperature, reduced weight and overall dimensions, reduced blackout area of the main reflector of the antenna.

2 cl, 3 dwg

Description

The invention is intended for use in the composition of radio devices for television, broadcasting and radio communications in satellite microwave communication systems.

To improve the parameters of two-mirror antennas, conical screens are installed along the perimeter of the edge of the counter-reflector [1]. Also known is a conical screen with an odd number of segmented protrusions, mounted around the perimeter of the edge of the counterreflector of a two-mirror axisymmetric antenna [2].

The aim of the invention is to increase the noise immunity and increase the noise figure of merit of the receiving system with an axisymmetric two-mirror antenna by reducing the thermal radiation of the environment and thereby reducing the noise temperature of the antenna.

To do this, in two-axis axisymmetric antennas, an open screen 4-5-11-10 can be installed, mounted on the edge of the counterreflector 3-10, conical in shape with the axis of the cone 7-9, coinciding with the axial axis of the antenna 6-9 and the top of the cone 7, located from the side opposite to the placement of the irradiator (figure 1). The angle of the conical surface of the screen 2-7-11 must be greater than or equal to the angular opening of the main mirror 1-6-12 (figure 1). When the angle of the solution of the conical surface of the screen 2-7-11, equal to the aperture angle of the main mirror of the antenna 1-6-12, the maximum screening angle is provided for a fixed value of the screen depth 10-11 (figure 1).

The depth of the screen 10-11 is selected depending on the required level of reduction in noise temperature by shielding the irradiating device from the thermal radiation of the earth's surface (figure 1).

Due to the open conical screen 4-5-11-10 located on the edge of the counterreflector 3-10, the effect of shielding the thermal noise of the earth's surface 13-8-14 is created (figure 2). With this form of the screen, the minimum shading area of the main mirror is achieved with the same screening effect.

Such screens in the reception mode can reduce the received power of thermal radiation from the surface of the earth directly by the irradiator. Thus, the total noise temperature of the axisymmetric two-mirror antenna decreases at small angles of inclination of the antenna to the horizon and the noise figure of merit increases.

For these purposes, a screen in the form of part of a conical surface 4-5-11-10 located on the lower part of the edge of the counterreflector 4-10 (Fig. 3), the perimeter length (L _E ) of which can be used, can be used

L _e = 2R _K arccos (ctg (φ ₀ ) tg (α)),

where R _K is the radius of the counterreflector, φ ₀ is the angular half-opening of the counterreflector 6-8-10 (Fig. 1) and α is the angle of the antenna to the horizon 6-8-16 (Fig. 3).

The upper part of the screen 2-5-4-3 (figure 1), supplementing it with a closed screen, reduces the thermal noise of the atmosphere, which is much less than the thermal noise of the earth, so this part of the screen practically does not reduce the overall level of thermal noise surrounding the antenna environment.

As a result of the use of such screens, the irradiator is shielded from receiving thermal radiation from the earth's surface, the overall dimensions are reduced, and the shading area of the main antenna mirror decreases.

The invention is illustrated by drawings, in which:

- figure 1 - open conical screen mounted on the edge of the counterreflector of a two-mirror antenna in the vertical plane of the cross section;

- figure 2 - installation of an open conical screen in the scheme of a two-mirror antenna in the vertical plane of section;

- figure 3 is an open conical screen in the lower part of the edge of the counterreflector of a two-mirror antenna in the vertical plane of the section.

LITERATURE

1. Eisenberg G.Z. and other VHF antennas. Ed. G.Z. Eisenberg. In 2 hours, part 2. M., “Communication”, 1977, 288 pp.

2. AC SU No. 1022247 A1, cl. H01Q 19/18, publ. 06/07/1983, p. 3.

Claims (2)

1. A two-mirror antenna consisting of an irradiator, an axisymmetric main mirror, a counter-reflector and a screen around the perimeter of the edge of the cone-shaped reflector with the axis of the cone coinciding with the axial axis of the antenna, characterized in that the conical screen located around the perimeter of the edge of the counter-reflector is not closed along the upper part edges. 2. The mirror antenna according to claim 1, characterized in that the angle of the conical surface of the screen is equal to or greater than the aperture angle of the main mirror.

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