The use of bandpass filters for modification of the zero method of measurements in microwave radiometers

Abstract

A microwave radiometer is considered whose principle of operation is based on modification of the zero measurement method with additional pulse-width modulation of reference signals generated with the use of selective properties of band-pass filters. Such modulation and processing of signals at the radiometric receiver output in conformity with a special algorithm make it possible to realize the zero measurement conditions in the radiometer. It is shown that with the knowledge of duration of the pulse-width signal used for controlling the additional modulator we can determine the antenna signal linearly related to this duration. The use of two different input units in the radiometer permits implementing the antenna signal measurements in various ranges of its variation.