Analysis and Correction of the Inter-channel Mismatch in Synthetic Aperture Radiometer

A Ka-band two dimensional synthetic aperture interferometric radiometer (SAIR) called SAIR-2D has been developed for concealed weapon detection. The inter-channel mismatch due to amplitude, phase and group delay differences between each receiving channel pairs can result in an undesired effect called fringe washing function (FWF). As the security application usually needs a wide field of view, the FWF is unavoidable and could lead to radiometric performance degradation. This paper presents a general method to analyze the impact of inter-channel mismatch on SAIR. Based on the analysis, the performance degradation of the SAIR-2D is mainly introduced by the group delay difference. To compensate the degradation due to group delay difference, a channel synchronization method is proposed in this paper. Validation experiments have been conducted on SAIR-2D. The experimental results show that the group delay differences are significantly reduced and can meet the requirements of SAIR-2D by means of the proposed method.