Description: 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.

Benefits: The result of the Phase 2 effort will include the delivery of two sensitive and highly integrated receiver systems with polarimetric measurement capabilities, operating at ~670 GHz and ~325 GHz. Their compact size and excellent sensitivity will demonstrate the value of innovative integration technologies that are described throughout the proposal. Additionally, Phase III efforts VDI will extend this technology throughout the frequency range of interest for atmospheric studies, roughly 50 GHz to 1 THz. The integrated receivers that will become available through this research will greatly improve the performance and reliability of airborne radiometers such as CoSSIR, while also enabling the development of more compact satellite receiver systems for programs such as ACE and CAPPM. CubeSats that are playing an expanding role in NASA�s future atmospheric missions will be enabled by the compact size and low power requirements. Deep space probes that study the atmospheres of planets and their satellites will also be enabled.

In addition to scientific applications such as atmospheric studies, plasma diagnostics and molecular spectroscopy; commercial test and measurement systems will benefit from this project. VDI presently markets a product line of frequency extenders for vector network analyzers (VNAs) and spectrum analyzers (SAs) for all frequency bands from 50 GHz through 1.5 THz. The technology developed through this project will allow VDI to develop more compact, cost effective and reliable frequency extenders. The reduced size will make the extenders more useful for a variety of applications, such as antenna test ranges and on-wafer probing. Antenna testing, in particular, will benefit from the availability of polarimetric receivers. Other applications include imaging systems for portal security and industrial process control. Finally, integration will not only reduce system size, but will also increase reliability, and, over the long term, reduce costs. Thus, integration is an important step in fostering the future development the entire field of terahertz technology.