Analysis of the Signal Response of a Scanning-Beam Millimeter-Wave Correlation Radiometer

An analysis of the response of a scanning-beam millimeter-wave correlation radiometer is presented with an emphasis on the spectral signal response. The derivation and subsequent analysis presented here focuses specifically on the effects of the natural oscillation of the signal, called the fringe frequency, as it pertains to rotating sensors. The amplitude and bandwidth of the spectral density are analyzed in multiple cases, including for tracking and nontracking antennas, and for situations in which the antenna beam or the fringe washing function of the correlation radiometer is wide and can be neglected. Closed-form solutions are found for the case where the antennas track the source. Theoretical and simulated responses are given, and experimental results are compared to expected results from the theory for a correlation radiometer designed for security sensing. Measured experimental results show minimal deviation from theoretical calculations, validating the theoretical models derived herein.