Reconfiguration Switch Matrix for Use on Board the Data Relay System Satellites

The increasing Low Earth Orbit (LEO) Spacecraft traffic and mission data communication requirements necessitates an increase in the real-time ground segment communication capability per orbit. The European Space Agency (ESA) Data Relay Satellite System (DRSS), consisting of three geo-stationary satellites, is thus seen to improve LEO spacecraft ground segment communications. In order to achieve the required frequency flexibility and interconnectivity in the DRSS, Reconfiguration Switch Matrices are required to switch incoming IF signals (from downconverters) to the appropriate upconverters and transmitters. This paper presents the feasibility study, design and manufacture of a redundant, 8×8 RSM at 5.5GHz for use on board the DRSS. The RSM includes the Microwave Switch Matrix (MSM) and the Distribution Control Unit (DCU). Several MSM architectures were identified, two of which could satisfy the system requirements for isolation and non-interruptive reconfiguration. These were analysed for optimum performance before appropriate selection, design and manufacture. The switch elements required custom designed switched amplifiers, in GaAs MMIC technology, for space and weight saving purposes. These MMIC´s were custom designed in order to maximise the isolation and minimise the power consumption and biasing requirements. Various DCU configurations were compared, with regard to Telecommand (TC) word format, Telemetry (TM) and monitoring and then designed. Finally, the RSM mechanical structure was designed for a minimum size and weight realisation. This design allows for modular 8×8 MSM expansion or redundant contraction (e.g. 4×4 Redundant).