A novel multi-reflector design for reducing sidelobes in center-fed antennas

Abstract

Recent investigations have revealed the possibility of substantially reducing blockage effects in center-fed cassegrain antennas. A multireflector design is proposed which uses a modified subreflector configuration to recapture most of the energy that would normally be lost due to blockage. The analysis described is based on physical optics and does not include the effects of edge diffraction. The results of the analysis indicate that the concept described can substantially reduce the blockage effects of center-fed Cassegrain antennas. Compared to the conventional Cassegrain case, the effective area blockage was reduced by a factor of the magnification squared. This resulted in about a 10-dB improvement in sidelobe level for the configuration analyzed. Reduced sidelobe levels, however, were achieved at the cost of bandwidth. Preliminary analysis of a variation of this concept indicates that a compromise solution that will result in reduced sidelobe levels and broader bandwidths is feasible. >