Sub-reflector extensions in shaped dual reflector systems

This paper investigates the performance of shaped systems with extended sub-reflectors with the goal of maximizing the sensitivity for a given feed pattern. It is shown that an extended sub-reflector may indeed provide improved sensitivity performance, especially if the system is tipped in the feed down configuration. The performance of systems illuminated with feeds with varying tapers is also investigated, with the results showing that sharper patterns provide higher sensitivity - especially when an extension is present. This result is consistent with that observed for unshaped systems.