Design and analysis of a multimode feed horn for a monopulse feed

The design of a multimode feed horn for use in a monopulse feed system is summarized. Both amplitude and phase patterns have been obtained and compared with measurements. The far-field amplitude and phase patterns are computed in consideration of achieving the desired aperture distributions for the sum and difference beams. The phase center of the horn is discussed in relation to the multimode excitation and frequency dispersion. It is shown that the phase center location moves as the mode content changes, and proper adjustment of the mode content will result in design optimization. Some tradeoff curves are also presented for design optimization