Overview of developments of the eleven Feeds

Paper in proceedings, 2013

An overview of different versions of the Eleven feed and recent development is presented in the paper. Eleven feeds have a nearly constant beamwidth and a fix phase center, with a performance of an aperture efficiency higher than 60%, −10 dB reflection coefficient, −0.2dB radiation efficiency, and −15dB cross-polar level, over a decade bandwidth. The Eleven feed can be very compact after applying newly developed optimization algorithms, and some new results of the feed in dual-reflector antennas are reported here.