A linearly-polarized dual-band diplexer in an offset reflector

This paper assesses the performance of a dual linearly polarized 45° incidence frequency selective diplexer in an offset parabolic reflector. Three different plane frequency selective surfaces have been studied¿single layers of concentric rings and double squares, and a four¿layer surface consisting of capacitive patch arrays. All three give operating bands near 22 GHz and 32 GHz. The peak linear crosspolar levels of the diplexer alone and in the offset reflector are discussed, together with the copolar sidelobe performance of the complete antenna.