Communications transponder performance for Japanese Communications Satellite-2 and prospects for future systems

Communications transponder for the Japanese Communications Satellite-2 (CS-2a and 2b) to be launched into a geostationary orbit by N-II launch vehicle in February and August, 1983, has been developed. The transponder is provided with six-channel K-band ($\text{30}\text{20}\text{GHz}$) transponder including beacon transmitter, which operates in the highest frequency ranges ever utilized on an operational communications satellite, and two-channel C-band ($\text{6}\text{4}\text{GHz}$) transponder. Receiver front end of the K-band transponder consists of a direct mixer followed by a 1.8 GHz IF amplifier and provides 8 dB noise figure. 20 GHz output power is 4 W by final amplification at 5-W TWTA. C-band transponder provides 4 dB noise figure and 4.3-W output power. Key factors for future high capacity transponder are also presented.