A Near-Field ISAR Measurement Method Using Array-Synthesized Cylindrical Waves with Environmental Coupling Analysis

This paper proposes a comprehensive simulation and experimental method for inverse synthetic aperture radar (ISAR) imaging of rotating targets based on synthetic cylindrical waves. The proposed approach is implemented through three key steps. First, a linear array combined with the Alternating Projection Method (APM) is adopted to optimize excitation coefficients for approximating cylindrical wavefronts. Second, the Iterative Physical Optics (IPO) algorithm is utilized to compute near-field scattering efficiently and extract environmental coupling effects. Finally, the Back-Projection (BP) algorithm is applied for image reconstruction. To rigorously validate the method, a comparative analysis of imaging results is conducted across three scenarios: simulation using the field synthesized by the Gaussian beam array, theoretical benchmarking using analytical cylindrical wave, and experimental measurement using a phased antenna array. Experimental validation using an 8-element X-band array demonstrates that the amplitude error of the synthetic field is less than 0.2 dB and the phase error is less than 2.5 within the phase-flat region. The imaging results from the array synthesis experiment align closely with those obtained from both the Gaussian beam simulation and the analytical benchmark. Furthermore, the simulations successfully extract environmental coupling components and provide theoretical guidance for the analysis of imaging interference. These results confirm the feasibility and effectiveness of the proposed low-cost array synthesis technique for near-field imaging and environmental coupling analysis.