Influence of the Metallic Shield on the Antenna Temperature Calibration for the Microwave Radiometer

In the calibration of a microwave radiometer, the calibration load is equipped with a metallic shield. The metallic shield is found to introduce aberration to the measurements of the antenna temperature. In this work, a ray-tracing model is constructed for the aberration analysis, which is based on the radiation transfer theory taking into account both the conductivity of the metal and the temperature distribution of the shield. Calculation results indicate that the temperature aberration due to the metal shield can be up to a few tenths of Kelvin, depending on the metal, the geometry of the shield and the size of the antenna. The calculation result is also compared with the experimental data.