Ground Calibration Experiment of Spaceborne Millimeter Wave Radiometer

ChangE|1(CE|1) will be the first satellite of China in lunar orbit. Its radiometer operates at 3.0, 7.8, 19.35 and 37 GHz in a nadir viewing mode. By now, the pre|launch experimental CE|1 Microwave Radiometer is developed. In this paper, an experiment on the ground calibration of 37GHz channel is carried out. First, the linearity and sensitivity of its receiver is obtained to be 0.9999 and 0.17 K, respectively, and satisfy the performance requirements, so CE|1 Microwave Radiometer can be calibrated through high and low temperature points: the high temperature point is from the matching load, the low one is from the liquid nitrogen refrigerated calibration blackbody target. Moreover, to amend the influence by the transmission network, the modified hardware radiative transfer model is built up. The antenna temperature calibration equation, which accounts for losses and mismatch, is derived finally based on the model and the error of calibration is less than 0.85K. The results provide a constructive reference to the further development of CE|1 Microwave Radiometer for launch.