Physical Optics Model of Side Lobe Nulling by Discs on a Parabolic Reflector

摘要

By mounting small disc reflectors that are moveable relative to the inner reflector surface of a parabolic dish antenna, nulls can be generated in the side lobe region of the power radiation pattern with minimal distortion effects to the main beam. A physical optics model of this antenna system is developed to investigate in a simplified direct manner the phenomena of phase nulling caused by disc movement. Array theory using isotropic radiators is used to sample the aperture distribution to approximate the far field electric field of the dish. A physical optics approximation for scattering off a flat metal disc is used for discs and feed blockage effects. (Theses)