An efficient, accurate and robust radiometer configuration for microwave temperature measurement for industrial and medical applications.

The theoretical and practical design of a type of microwave radiometer particularly suited to industrial and medical temperature measurement is described. The use of sequential switching of source and reference signals with synchronous demodulation of switched signal components gives an efficient and robust instrument configuration. The radiometer measures the true, matched-impedance effective temperature of the coupled source. Changes in noise-figure, gain or frequency response of the radiometer microwave amplification do not affect the temperature measurement. Practical microwave radiometers using this configuration can be simply calibrated, and have inherently stable calibration and excellent accuracy.