A Real-time Calibration Method of Visibility Function for Passive Millimeter Wave Imaging

This paper presents a real-time calibration method for the visibility function of millimeter wave passive imaging, which can effectively correct the multiplicative and additive errors of the visibility function in real time. In this method, the phase shifter is used to adjust the phase of the local oscillator periodically, the visibility functions corresponding to different local oscillator phases are established into equations, and then the visibility functions are estimated by the least square method. After that, the real-time calibration algorithm of visibility function is simulated by MATLAB, and verified by the 256 channel passive millimeter wave imaging (PMMW) system prototype developed by Beihang University, which proves the correctness of the method. Experimental results show that the results obtained by the visibility real-time calibration method can be directly used in the reconstruction of brightness temperature image.