Back-Propagation Near-Field Far-Field Transformation for Monostatic RCS Determination

The near-field far-field transformation (NFFFT) for near-field (NF) measurement on arbitrary scanning surfaces requires solving a linear equation of plane wave spectra unknowns. Based on the time-reversal (TR) principle, this article proposes a back-propagation NFFFT (BP-NFFFT) for monostatic radar cross section (RCS) determination. In the proposed approach, the plane wave spectra solution can be directly obtained from the back-propagation (BP) field, significantly accelerating the process compared to the conventional NFFFT methods. Numerical results demonstrate that the proposed BP-NFFFT achieves accuracy comparable to the conventional NFFFT, even for complex targets measured on irregular sampling surfaces, while significantly improving computational efficiency. The sensitivity of the proposed approach to position error is also analyzed.