The design, main stages of development process and simulated characteristics of a high performance extended C-band 3.4-4.8 GHz feed system for reflector antennas of dual circular polarization satellite communication earth stations are presented in this paper. The feed system includes an iris polarizer, a 45° square waveguide twist-transition, and an orthomode transducer based on a double-ridged junction. All these components have been optimized for the operation in extended C-band 3.4-4.8 GHz. VSWR of the developed dual circular polarization feed system is less than 1.14, its crosspolar isolation is higher than 30 dB.