Correction for Phase in Micro-Rotation Method of Tomography Using Group Delay

In our previous paper, we proposed a novel method of microwave tomography in which the target echo position in two dimensions can be achieved by combining time-domain signals generated by vector network analyzer and orderly variation of optical path contributed from microrotation (Lin, Chiu, and Lee (2022)). In this study, a correction approach based on group delay is proposed for dealing with the phase-wrapping problem if the rotational interval is not quite small. The approach has been verified with the three-target experiments, and the corrected image precisely showed the positions of the targets.