A simple design method of multimode horns

A new design method of multimode horns is proposed. For multimode horns of a given aperture diameter, the horn-flare half-angle and the diameter of the horn´s phasing section are determined at first through a mode analysis on the horn´s flare discontinuities. We then fix the two parameters, leaving the length of the horn´s phasing-section the only parameter to be optimized to have a desired radiation pattern. In comparison to the conventional design method, which iterates all the three structural parameters, this method is rather simple and yet is able to yield good design. A practical example designed at the 5-mm band is given here and its measurement results are presented for comparison.