Improvements in the Development of Coaxial Feeds for Paraboloidal Reflector Antennas

The coaxial feed for front-fed paraboloidal antennas as known from previous papers, by which an increase of aperture efficiency and a decrease of spillover is achieved, was simplified considerably in construction and improved in bandwidth. The aperture field distribution of the feed, which is necessary for an approximately sector-shaped rotationally symmetric feed pattern, is achieved by the excitation and superposition of H12-, E11- and H11-modes, however, the modes are different from those superimposed in earlier constructions. The modes are excited by aperture coupling and the means of excitation are explained. The feed dimensioning was optimized experimentally. The aperture efficiency of paraboloids with these feeds will be reported.