Improving the symmetry of radiation patterns for offset reflectorsilluminated by matched feeds

The large difference between the dominant sidelobe levels in the asymmetric and symmetric plane radiation patterns of the short-focal-length offset paraboloids is minimized by illuminating the reflector with a prime-focus tilted matched feed. The amplitude of the asymmetric mode (TE₂₁) component in the matched feed is numerically evaluated for achieving an optimum peak cross-polar level. Effect of the feed tilt on the reflector efficiency is also indicated