Feed support blockage in symmetric paraboloid reflectors

The effects of the primary feed supporting struts on the radiation patterns of a symmetric paraboloid reflector are investigated. Both linear and circular polarization of the feed are considered, and the reflector secondary fields are generated using the physical optics approximation for the surface current on the reflector. The strut fields, on the other hand, are computed by assuming the strut currents as those generated on an infinite cylinder illuminated by a plane incident wave. For struts of circular cros-section, the over-all radiation patterns of the reflector are computed and compared with those of an unblocked reflector. Based on this comparison, the effects of the strut dimensional parameters on the reflector gain, sidelobe levels and the cross-polarization are determined and presented graphically.