Beam Waveguide Feed for Frequency Re-Use in Cassegrain Antennas

The use of a beam waveguide feed for a Cassegrain earth station antenna has several mechanical advantages over a conventional feed. To ascertain the suitability of this type of feed for orthogonal polarization frequency re-use applications, a near-field diffraction analysis has been made of a configuration comprising offset sections of paraboloids. Emphasis has been placed on depolarization by the beam waveguide reflectors, the effect of inherent cross-polarization due to an imperfect feedhorn, and the effects of misalignments within the reflector system.