Evaluation of disturbance in the antenna calibration of the microwave radiometer

In the microwave radiometer calibration, the calibration low temperature load immerged in the liquefacient nitrogen is equipped with a metallic shield. The metal shield, the environment thermal noise and the inverse radiation are found causing aberration on the calibration measurement. A ray- tracing model is constructed for the metal shield aberration and the full-wave EM simulation is implemented in the two latter aberrations. The influences from the corresponding disturbances are evaluated numerically in this paper.