Spacecraft front-end technology

Spacecraft receivers require technologies which combine optimum RF performance with robustness and low mass, while meeting volume constraints. The adaptation to the spacecraft application is most significant in the instrument front-end, comprising antenna, antenna feed, and mixer. The millimetric band from 89 GHz upwards is currently characterised by the use of quasi-optical feeds and subharmonically pumped double sideband mixers. In recognition of the increasing need for ever higher operating frequencies, and the stringent mass/volume constraints associated in particular with spacecraft environments, BAe Space Systems has developed an appropriate set of accurate predictive design aids, which have been verified against hardware. A key front-end component whose design is significantly constrained by the spacecraft environment is the mixer. Subharmonically pumped double planar diodes are robust. Experimental work using air-bridged and solid coupling structures was undertaken, and typical performance parameters produced