An Effective Nonlinear Phase Compensation Method for FMCW Terahertz Radar

The nonlinearity of signal usually leads to the range profile blurring and defocusing in the terahertz (THz) radar ranging, which should be compensated to achieve a well-focused range profile. In this letter, an effective nonlinear phase compensation method is proposed to compensate for the signal distortion caused by the radar waveform nonlinearities. It comprises two processing steps, namely, coarse phase compensation and precise phase compensation, which are based on the time-frequency distribution and the phase gradient autofocus algorithm, respectively. The proposed method is a nonparametric method and can eliminate the errors caused by phase discontinuity of the dechirped frequency-modulated continuous-wave (FMCW) signal. Furthermore, the compensation method can be used in the processing of multi-period real data that are obtained from the FMCW THz radar.