SU1753522A1 - Two reflectors aerial - Google Patents

Abstract

This invention relates to mirror antennas. The purpose of the invention is to increase the gain, decrease the noise temperature, increase the slope of the pendling characteristic, and decrease the side lobe level — achieved by making the dielectric support solid and shifting the counter reflector toward the irradiator .1 Il.

Description

The invention relates to antenna technology and can be used in radar stations, in space communication systems, in radio astronomy.

A known two-mirror antenna comprising a main reflector, a counter reflector, an irradiator, a hollow dielectric support, the surface of which is made in the form of a body of rotation with a rotation axis coinciding with the focal axis of the antenna, which is a parabola described by the equation

xs; 0.5d - () tgBMy: 4 0.25 d2 tg BM

where x and y - the current coordinates of the parabola;

d - diameter counter-reflector;

BM is the angle of irradiation of the main reflector;

H is the distance from the focus of the main reflector to the irradiator;

d is the distance from the irradiator to the intersection point of the parabola with the focal axis.

The antenna has the disadvantage of lower antenna gain, increased antenna teMnepafypa and increased side lobes due to dissipation of a part of the energy of the irradiator past the counter reflector of the mirror system.

Closest to the proposed is a two-mirror antenna consisting of an irradiator, a solid dielectric support, a counter reflector and a main reflector. The dielectric support is made in the form of a truncated cone, the slope of the generator and the dielectric constant of which provide the total internal reflection of the electromagnetic energy of the irradiator from the dielectric-air interface. After reflection from the counterreflector, the electromagnetic energy again spreads in a continuous dielectric support and again enters the dielectric-air interface at different angles. Moreover, the closer the beam is to the axis of the mirror system, the greater is the angle of incidence of the beam on the support and the greater is the angle of refraction. This causes the ampli to drop (L

with

h

Ca

the next

go

the distribution in the central part of the mirror and the loss of electromagnetic energy.

The disadvantages of the prototype are a decrease in the gain factor, an increase in the level of noise temperature and side lobes, and in systems with differential directional diagrams - a decrease in the slope of the scaling characteristic. ,. The aim of the invention is to increase the gain, decrease the noise temperature of the antenna, increase the steepness of the direction-finding characteristic and decrease the side lobe level.

This goal is achieved by the fact that in a two-mirror antenna containing an irradiator, a counter reflector, a dielectric support is made solid, and the surface of the counter reflector is shifted towards the irradiator by

Ax (1-rohr A °

Where

, 25d () (- + - l

4 v tg W tg AM

one

sin BM

).

AM is the aperture angle of the counter-reflector from the phase center of the irradiator;

s is the dielectric constant of the dielectric support material.

The drawing shows the block diagram of the proposed two-mirror antenna.

The two-mirror antenna consists of irradiator 1, solid dielectric support 2, counter reflector 3, and main reflector 4.

The principle of operation is as follows.

The electromagnetic wave emitted by the irradiator 1 passes the body of the dielectric support 2, hits the counter reflector 3 and is reflected back to the main reflector 4. The shape of the surface of the solid dielectric support ensures that the waves reflected from the counter reflector at small angles coincide. with the surrounding space and thereby ensures the passage of electromagnetic energy with insignificant losses. This leads to an increase in antenna gain, a decrease in noise temperature and side-lobe level, and in antennas with differential

diagrams to an increase in the steepness of the direction-finding characteristics. The gain depends on the antenna parameters: the diameters of the main reflector and counter reflector,

the focal distance, the position of the irradiator and the top of the dielectric support, the dielectric constant of the material, the angles of irradiation of the main mirror and the reflector, the level of illumination of the main mirror

reflector, etc. So, for example, with F / D - 0.3; e- 1,2; d / D - 0.12; H + b 0.965d, the gain in the gain factor is 23%, a decrease in the noise temperature of 15 K, and an increase in the steepness of the direction-finding characteristic by 10%.

Claims (1)

Invention Formula A two-mirror antenna containing a reflector, a counter reflector and an irradiator, connected by means of a dielectric support made in the form of a body of rotation with an axis coinciding with the focal axis, which forms a parabola, is described by the equation .5d- (H + d) tgBMy2 + H + a 0,25d2tgBM where x and y are the coordinates with the origin at the focal point, and the axis coinciding with the focal axis; d is the diameter of the counter-reflector; Vm - the opening angle of the reflector from the focal point; H is the distance from focus to irradiator; (e) distance from the point of the irradiator to the point of intersection of the forming dielectric support with the focal axis, characterized in that in order to increase the gain, decrease the noise temperature, increase the steepness of the direction finding characteristic and reduce the side lobes, the dielectric support is solid and the surface of the counter reflector is shifted toward the irradiator by 50 DH (1TSH ) Aho, Where , 25d (vF-1) ( one one tg w tg AM one sinBM ). AM is the aperture angle of the counter-reflector and dielectric permittivity of the mafase center of the irradiator; the electric support material.