Following a brief review of the theory of operation, characteristics, and applications of the modern microwave radiometer, the Dicke radiometer circuit is analyzed by the autocorrelation function-power spectrum method. The treatment achieves a greater generality than prior investigations although the method is, in general, similar to that used by Goldstein. The major improvement of this treatment is a result of replacing the detector characteristic assumed by Dicke and Goldstein,

, with a general representation. The final result shows that the sensitivity of the radiometer is independent of the detector characteristic. In addition, the results of Dicke and Goldstein were corrected and found to be the same as the sensitivity obtained in the present work. This paper illustrates the method and describes the results, but omits the main body of routine calculation. The theoretical results were experimentally tested.