Characterization and Measurement of Radiometer Stability

For the characterization of radiometer noise and stability a new and very practical method is introduced. It consists of the measurement of the "Allan-variance" well known for the characterization of the stability of frequency standards. The plot of the Allan variance versus integration time allows one to determine the different types of fluctuations of the radio-meter output signal. In particular, the best range of integration time for optimum use of the system can accurately be evaluated. Theoretical considerations and experimental results are presented.