Calibration of Visibility Samples for Real-Time Passive Millimeter Wave Imaging

A Ka-band 1024-channel passive millimeter wave (PMMW) imager with 1 GHz bandwidth called BHU-1024 has been developed by Beihang University for security screening. uses linear phased array to obtain resolution in the horizontal direction and aperture synthesis vertical direction. The non-ideal characteristics of hardware cause decrease system sensitivity always blur reconstructed image, hampering applications where high accurate recognition are emphasized. Hence, effective calibration is a prerequisite ensure quality image. In this paper, overall approach presented, focusing on main errors relevant instrument design: basic correlator counts preprocessed correct comparators offset quadrature error. residual estimated continuously sweeping local oscillator (LO) phase. And baseline error, novel approach, which makes use an external noise source mounted metal frame, proposed tackle problem. results simulation measurement demonstrate validity approach. Finally, actual calibrated data used reconstruct further validates process.