High Performance Dual Circularly Polarized S- Band Feed

A high performance feed for 11 meters dual shaped reflector system is designed, developed and tested. It is a dual circularly polarized monopulse tracking feed with a measured axial ratio of 0.5dB over the required frequency band of 2GHz to 2.3GHz (Uplink: 2.02GHz -2.12GHz, Downlink: 2.2GHz-2.3GHz). This feed consists of four high performance Teflon dielectric radiating elements. Each dielectric element has a gain of 16.5dBi and are SODFHG DSDUW LQ [ FRQILJXUDWLRQ WR REWDLQ WKH DPSOLWXGH WDSHU IRU WKH VXE UHIOHFWRU 7KH feed level measurement was done in compact antenna test facility of ISAC, Bangalore. Total antenna system with 11 meters reflector was characterized in outdoor test range at Sohna. Measured difference pattern null depth is -40dB, measured gain is 46dBi and sum pattern peak to difference pattern peak difference is 7dB. The measured G/T of the antenna system is 25dB/K and the cross-polar levels are better than -30dB. In this paper design of the feed system and the measured results are presented.