Hard waveguide feeds with circular symmetry for aperture efficiency enhancement

Hard horns or waveguide feeds with circular symmetry have been studied with respect to gain (aperture efficiency) and crosspolarisation. The corrugated or strip-loaded representations of these feeds give almost identical radiation properties when surface waves are neglected. The contribution from the wall region increases the gain and crosspolar bandwidth of the feed. The gain increases and the crosspolar bandwidth decreases with increasing waveguide diameter and wall permittivity. The hard horns may be useful in cluster feeds and limited scan arrays due to reduced size and weight