Surface-current analysis of distorted reflector antennas

An important requirement in satellite antenna design is the prediction of the antenna performance when it is placed in the space orbital environment. An accurate estimate of its performance deterioration, caused by antenna distortions which are induced by the temperature extremes encountered, should be obtained. A method suitable for this type of analysis of reflector antennas is presented. It involves the division of the reflector surface into triangular elements whose distortions are computed using a structural analysis program (NASTRAN). The currents flowing on each distorted elemental surface are then used to give the diffracted fields. The computed results of an offset fed reflector are given. A way is suggested, which makes use of monopulse tracking, to minimise the performance degradation caused by the surface distortion.