Dual reflector shaping for realistic frequency dependent feed patterns with specific secondary field pattern targets

This paper presents an optimization based strategy to design shaped dual reflector antenna systems to meet secondary pattern specifications when a realistic feed pattern is used to illuminate the system. For this application the secondary pattern performance of a similar unshaped system using the same feed is assumed to be known. Using the ideal mapping from the primary to the secondary patterns, the ideal performance of the unshaped as well as the shaped systems may be calculated. Full wave or asymptotic techniques are used to predict the actual unshaped system performance, and comparisons between the ideal and actual unshaped performance are used to estimate the actual shaped performance in terms of the desired secondary pattern specifications. This method allows for rapid optimization of the shaped mapping to produce a system with superior performance to the unshaped system when a realistic, frequency dependent, feed pattern is used. Simulations of the optimized shaped system with the realistic feed pattern shows the expected improved performance over that of the unshaped system.