Calibration procedure of a microwave total-power radiometer

A total-power radiometer built in combination with a beacon receiver is being used for low-level attenuation measurements. This experimental receiver was built to measure atmospheric propagation impairments, using the ITALSAT satellite 50 GHz signal. The radiometer is mainly used to provide the reference level for the beacon measurements. Its precision should be better than /spl plusmn/3 K, for low attenuation levels, in order to have 0.1 dB accuracy in the attenuation measurements. A suitable calibration procedure is described.