Feed for a four-horn monopulse tracking radar

A pyramidal horn for a four-horn feed and a perfectly conducting parabolic reflector of circular aperture minimizing the angular tracking error have been considered. A nominal frequency of 10 GHz and a focal length to distance ratio of unity were chosen for purposes of numerical evaluation. The analysis of the pyramidal horn is approached from the sectoral horn approximation which is usually used in practice. Following the analysis of the horn, the aperture distribution is decomposed into the horn eigenfunctions, and the waveguide aperture excitations are found. The monopulse sums and difference signals are then defined, and the variance of their ratio is calculated. From this variance, the root-mean-square angular tracking error is calculated which provides the criterion for the design of the pyramidal horn aperture dimensions.<>