Satellite communication subsystem design for the Indonesian Archipelago

To meet the requirements of the Indonesian Archipelago, an advanced communication subsystem was designed which incorporated many key system advances. Orthogonally polarized grid reflectors, offset feed with displaced foci, provide shaped beam coverage of orthogonal polarizations with maximum reflector area for each. The 24 channels of 36 MHz each are implemented by functionally separate horizontal and vertical repeaters. High efficiency traveling wave tubes with triply depressed collectors provide downlink power amplification, while a 5 for 4 redundancy implementation insures reliability. Channel selectivity is established by elliptic function input and output multiplexers utilizing circulator dropping techniques on the input and common manifold combining on the output. As a result of this system implementation, it has been possible to achieve 34 dBW downlink EIRP and -5 dB K uplink G/T with a much smaller spacecraft than previously achieved.