An Adaptive Nonlinear Phase Error Estimation and Compensation Method for Terahertz Radar Imaging System

Terahertz (THz) radar imaging has been getting a lot more attention in recent years because it has a faster frame rate and better resolution. However, nonlinear phase errors resulting from the immaturity and instability of THz devices inevitably affect the transmitted signal of THz radar imaging systems, causing the range image to blur. In this work, we present an adaptive correction approach for improving the imaging quality of THz radar by the elimination of nonlinear phase error. First, the nonparametric model is created with high accuracy; this model accounts for nonlinear phase errors introduced by the signal source and other broadband hardware devices like the frequency multiplier. After that, the suggested technique employs nonlinear phase error estimates and compensation by iterative optimization, with the picture contrast of multiple pulse compression serving as the evaluation criterion. The proposed method has been validated through the use of both synthetic data and field data gathered with a 0.22 THz airborne SAR equipment. The experimental results further highlight the suggested method's high robustness, low computational cost, and several potential uses.