High-power units for GALS R16 transponders

The basic design principles and performance of the high-power units for the GALS R16 transponders are presented. An overview is given which details the activities at Dornier Satellitensysteme GmbH for improved TWTA for future satellite transponders. The mission of the GALS R16 spacecraft is the support of the Russian Ku-band TV network which allows simple and low-cost on-ground subscriber units using antennas of 60 cm to 90 cm diameter. This requires a satellite EIRP of 51 dBW. To achieve the required radiated field strength, travelling wave tube amplifiers (TWTA) at power levels of 100 W at the end of life (EOL) are used in the 24 transponder channels (4:6 redundancy). Common design activities of JSC INFORMCOSMOS, SPAR Aerospace and Dornier Satellitensysteme GmbH led to a TWTA design which meets the Russian spacecraft requirement and achieves the most perfect features achieved during recent space programs executed by Dornier. Additional transponder equipment as waveguide isolators and switches are built by COMDEV Canada and supplied by SPAR Aerospace. The TWTA are designed, integrated and tested by Dornier using TWTA supplied by TTEG (former AEG) Germany and electrical power conditioners (EPC) developed, space-qualified and manufactured by Dornier Satellitensysteme GmbH, Germany.