Investigation on Conjugate Matched Feed for an Offset Reflector

The paper presents design procedures and simulated results of rectangular and cylindrical conjugate matched feed. The rectangular conjugate matched feed contains higher order TE11 mode in addition with dominant TE10 mode. The TE11 mode is generated by inserting a single metallic post. The cylindrical conjugate matched feed contains higher order TE21 and TM11 modes in addition with dominant TE11 mode. The TE21 mode is generated by inserting a three metallic posts 120 degree apart and the TM11 mode is generated by taper discontinuity. The radiation and transmission characteristics of both the conjugate matched feeds are optimized and presented. In rectangular conjugate matched feed, around 26 dB improvement in cross-polar component has been achieved as compare to conventional rectangular feed. In cylindrical conjugate matched feed, 28 to 35. DB improvement in the cross-polar component has been achieved as compare to conventional cylindrical feed by varying post length from 4.5 to 6.5 mm. The behavior of cross-polar component over frequency range 9.7 to 10.3 GHz has been studied.