Measurement and Calibration Methods for Full-Polarization Characteristics of Radar Targets at Subterahertz Frequencies

This paper presents a comprehensive measurement and calibration methodology for full-polarization characterization of radar targets at sub-terahertz (THz) frequencies. A novel three-object polarization calibration technique is proposed to address amplitude and phase imbalances in the measurement system. The method is implemented using a sub-THz radar cross-section measurement platform with twist waveguides for polarization switching. Experimental validation in an anechoic chamber demonstrates the method's effectiveness, achieving phase mismatch within 20°, polarization isolation better than 15 dB, and co-polarization amplitude imbalance below 2 dB. The calibrated data's accuracy is further confirmed through Cameron decomposition, showing excellent agreement with theoretical predictions. This work provides a robust framework for precise polarization characterization in the sub-THz regime, with potential applications in radar target recognition and imaging.