The enabling technologies of the Geostationary Synthetic Aperture Microwave Sounder (GEO/SAMS)

The system architecture and two key enabling technologies required to implement a Geostationary Synthetic Aperture Microwave Sounder (GEO/SAMS), a millimeter-wave temperature/weather profiling instrument concept which can provide continuous, high spatial resolution observations from geostationary orbit, are described. The baseline concept validation instrument is a nadir pointed, fixed "Y-array" of 64 receiver elements, operating at 4 frequencies near 50 GHz. Adjacent element spacing of 1.9 cm and a 0.8 m equivalent aperture provide 300 km surface spatial resolution. The architecture is fully scalable, allowing the number of receivers in the array to grow to provide whatever resolution is eventually desired. Follow-on instruments can provide better than 50 km surface resolution, and can also incorporate moisture sounding at 183 GHz. The enabling technologies include advanced mm-wave GaAs or InP HEMT MMIC technology which allows the low-cost fabrication of many lightweight, miniaturized receiver elements, and utilization of 0.25 micron, Cu-interconnect CMOS to realize a highly integrated, real-time, parallel cross-correlator architecture. The entire concept validation system can be packaged in a system configuration that weighs no more than 58 kg, consumes less than 185 watts continuous power, and provides scientifically meaningful data at a downlink rate not exceeding 750 kbps continuous.