Accurate characterization of high power SSPA under multicarrier operation for satellite communications

This paper presents the challenges faced and an accurate technique used to characterize high power SSPA under the multicarrier operation when used for on-board satellite communications. 100W UHF band SSPA has been developed for operation with five QPSK modulated carriers for a communication payload. The communication satellites carry large number of transponders in different frequency bands to cater to large market segments. Optimization for higher throughput has always been challenging to the payload and sub-systems designers to maximize the efficiency and utilization of the available hardware as these are power and bandwidth hungry as well as huge costs are incurred on per kilogram of space hardware launch. RF SSPAs in general are the most power consuming units with designers struggling to improve upon the efficiency. The system designers on their part optimize the payload to operate in multicarrier format to utilize the SSPAs in two or more frequency bands simultaneously. This multicarrier operation poses a challenge for proper characterization of SSPA and transponder on ground to predict the in-orbit performance.