A 680 GHz Direct Detection Dual-Channel Polarimetric Receiver
In this work, a 680 GHz direct detection polarimetric receiver for the sensing of cloud ice in the upper atmosphere is presented. The minimum noise figure for the horizontally and vertically polarized channels are 10.5 dB and 10.6 dB, respectively. The receiver utilizes 25 nm indium phosphide (InP) HEMT low noise amplifier MMIC technology, which provide approximately 36 dB of RF gain per channel. Including linear regulators, the polarimeter consumes 1 W of DC power and measures 2.6 cm x 3.1 cm x 5.8 cm. This work represents the first 680 GHz direct detection polarimeter.