Calculation of the phase center of an ultra-wideband feed for reflector antennas

Next generation ultra-wideband (UWB) radio telescopes require UWB feeds for reflector antennas. Different from narrow band feeds, how to determine the optimal phase center location for a UWB feed over a wide operating frequency band has not been investigated much and therefore analysis and discussions on this issue are needed. In this paper, a method for calculating the optimal phase center of a UWB feed is presented. Examples of the Eleven feeds, a decade bandwidth feed, are used to demonstrate the applications of the new method.