Near-Field Electromagnetic Scattering Accurate Prediction for Millimeter-Wave and Terahertz Radar Technology

Millimeter-wave radar and terahertz radar are increasingly applied in the near-field region. Near-field scattering characteristics of targets need to be described in the spherical wave propagation model and non-uniform target illumination. A scattering characteristics prediction analytical method based on generalized radar range equation for near-field targets is proposed in this paper. The partial illumination effects of the targets and antenna near-field radiation characteristics are considered in this method. The scattered field of near-field targets is related to distance, target size and antenna radiation pattern. Near-field scattering characteristic of canonical targets (plate at 24 GHz and cylinder at 240 GHz) and a realistic vehicle model are calculated and validated by full-wave electromagnetic simulations using software Ansys HFSS and published literature, achieving deviations below 1 dB. The proposed approach provides both physical insight and fast evaluation compared with numerical surface-integration algorithms and full-wave simulation method. It can be applied into the high-resolution near-field imaging, short-range sensing and 6G terahertz systems.