Sub-millimeter Wave Compact Correlation Radiometers

The design and measurements of direct-detect and heterodyne correlation radiometers around the 183 GHz water line are presented. The measured noise temperature of these receivers is under 900K. The DC power draw is 0.5 W and 8.0 W for the direct-detect and heterodyne receivers respectively. The correlation radiometer architecture improved the integration time for ideal radiometer performance of the heterodyne radiometer from <10ms to >1s. For the direct-detect architecture, it is shown that RF phase switching is required to realize the improvement of the correlation architecture.