D- and G-Band Correlating Radiometers

Correlating radiometers are presented at D-band (100–120 GHz) and G-band (160–185 GHz). The D-band system is a heterodyne receiver focused around the 118.75 GHz oxygen line and the G-band system is a direct-detection pseudocorrelating receiver focused around the 183.31 GHz water-vapor line. These systems are integrated into multiple waveguide blocks to facilitate troubleshooting and to enable different RF filters to be applied to the low noise amplifier (LNA)-based front ends. Discussion of the data-processing is presented for both systems. The D-band system has a noise temperature of 410 K at 120 GHz. The correlated output of this system increased the Allan time from 100 ms to 7 s. The G-band system has an average noise temperature of 780 K, with an increase in Allan time from 1 ms to 10 s.