Shaping the H-Plane Pattern of a Pyramidal Horn

The effect of loading the E-plane of a pyramidal horn with a thin metal plate is examined both theoretically and experimentally. A model using aperture field integration extended to include reflections from the walls of the horn and the plate was developed and gave a good fit to experimental data. The far field pattern of such a plate loaded horn can be modified in the H-plane and where necessary sharpened by adjustment of the position and size of the plate. When fitted with a lens the horn can be used to feed efficiently a Gregorian antenna system for high resolution passive millimetric imaging.