Fast Gaussian beam based synthesis of shaped reflector antennas for contoured beam applications

A relatively efficient procedure is proposed, which combines a novel Gaussian beam (GB) approach for fast computation of reflector antenna radiation patterns with an iterative optimisation technique, to synthesise a shaped reflector surface for contoured beam applications. The GB approach employs relatively few Gaussian beams as electromagnetic basis functions to represent the field radiated by the feed; each of these GBs launched from the feed then reflects and diffracts from the reflector surface to yield the radiation field produced by the reflector antenna. Closed form expressions are used for calculating this GB reflection and diffraction; consequently, the reflector radiation pattern, which needs to be computed repeatedly in any iterative synthesis procedure, can be obtained in an extremely rapid fashion via the present GB method. In contrast, the conventional procedure, which requires a numerical integration of the currents induced by the feed over the large reflector surface to calculate the radiation field, is far less efficient and lacks physical insight. Furthermore, the GB approach is used in conjunction with a fast and convergent synthesis procedure which is developed via a modification of the usual steepest descent method (SDM) to ensure a more global reflector shaping optimisation and smooth contoured beam patterns. Numerical results are presented to validate the proposed approach.