Influence of side radiation on one-reflector antenna parameters

Abstract

The side lobes of antenna's directive pattern cause a decrease of its gain coefficient, degradation of noise protection of radioelectronic systems equipped with this antenna, harmful effect of the electromagnetic irradiation on the environment. Especially important is reduction of side lobes of the directive pattern of antennas of radiometric systems for remote sensing of atmosphere, hydrosphere and Earth surface. In this connection the investigation to find opportunities to reduce the side irradiation of one of the main types of sharp-directed mm-band antennas -reflector antennas -is topical and urgent for many practical applications in scientific instrument-malung and technique. The subjects of investigation in this work are levels and law of reduction of side lobes of dlrective pattern of parabolic reflector antenna. The electrodynamic model, algorithm and computer program for calculating the direction characteristics of the antenna being investigated are described in the [l-21. The system ((reflector -irradiaton) is being calculated, and the developed programs allow investigation of any variants of reflector-parabolic, spherical, intermediate variants between parabolic and spherical [ 11, axes-symmetric and with removed irradiation at any variant of waveguide or horn irradiator. The Fig. l(a,b) present the dependence of the first side lobe level (SLL) and the gain coefficient (G) of the axes-symmetric one-reflector parabolic antenna with an irradiator in the form of open end of round waveguide on the diameter of irradiator, referred to the wave length.