Radio-astronomy antennas for 3 deg K cosmic radiation measurements

Antenna requirements for studying the 3 K background radiation are discussed. A 10-15 degree half-power beam width is a reasonable compromise between a large antenna beam for reducing the contribution of discrete sources in the field of view and a narrow beam needed to recognize anisotropies. An additional requirement is extremely low sidelobes and backlobes and excellent matching at the antenna input in order to minimize the antenna noise contribution. The radiation performance of a horn reflector antenna can be improved by corrugating the feeding conical waveguide. The results of a theoretical investigation of the horn reflector configuration using a specially developed computer program are described. The effect of a corrugated horn reflector on the radiation characteristics of the conical waveguide flare angle of the main aperture radius is shown.