Confocal parabolic reflector antenna design trade-offs
Three dual reflector configurations were designed and examined in detail. These are: on offset confocal parabolic antenna fed by a small phased array (image plane system) with both small and large magnification ratios, and a center-fed Cassegrain reflector antenna with a defocused feed array. Simulations show that the dual reflector configuration, center-fed by a phased array, while mechanically desirable, possesses high sidelobes as a result of aperture blockage. The offset-fed configuration, being free of blockage, can achieve very low sidelobes, the level being a function of the feed size used. If elements with amplitude excitations from 0 to -20 dB are activated in the feed array, the secondary sidelobes will be typically below -35 dB.<<ETX>>