640 GHz Heterodyne Polarimeter

This proposal is responsive to NASA SBIR Subtopic S1.02: Microwave Technologies for Remote Sensing, specifically the interest in the development of a 640 GHz Heterodyne Polarimeter with I, Q, U Channels. Suitably compact, light-weight and power efficient heterodyne instruments are required to enable polarimetric measurements for microphysical parameterization of ice clouds applicable to NASA's planned Aerosol, Cloud and Ecosystems (ACE) mission. Through the Phase 1 effort, VDI demonstrated the feasibility of an integrated 640 GHz polarimetric receiver. This included the demonstration of a 670 GHz LNA module and an OMT, each being compatible with full integration with the mixer diode based down-convertor. Goals of the Phase II include optimization of the OMT, development and evaluation of a fully integrated 670 GHz polarimeter, development of evaluation procedures to ensure the polarimeter meets NASA requirements, and development of a second prototype at 325 GHz to demonstrate the scaling of the technology. The estimated specifications of the 670 GHz prototype include receiver noise temperature ~6,000K (SSB at the horn aperture), power requirement 6W, volume ~1.5? x 1.5? x 0.75?. The goal isolation between polarizations is 20 ? 25 dB. Both integrated polarimeters will be delivered to NASA GSFC. Through Phase III, VDI will ensure that the technology is extended throughout the frequency range of interest for NASA?s atmospheric missions, roughly 100 GHz through about 1 THz.