Physics-based forward modeling of edge diffraction scattering centers for complex coated scatterers.

For low-observable targets, particularly those treated with material coatings, edge diffraction is an influential scattering mechanism. Although scattering center (SC) models can provide an effective sparse representation of local scattering mechanisms, the evolution from diffraction fields to SC models has not been systematically derived or quantitatively described for arbitrarily shaped edges and material coating conditions, which limits the accurate parameter characterization of edge diffraction SCs. Accordingly, this paper proposes an automated forward modeling method for coated edge diffraction SCs, grounded in the physical theory of diffraction (PTD). Spatial radiation expressions for straight edge and curved edge diffraction SCs are derived based on PTD and impedance boundary conditions. Then, geometric topology and visibility analyses are integrated to automatically identify, classify, and separate effective edge structures for given incidence directions. On this basis, physical correspondence from edge geometry, incidence conditions, and coating material properties to SC parameters is established, revealing the physical formation mechanisms of SCs and leading to an interpretable modeling method for edge diffraction from complex coated scatterers. Validated through comparisons with high-frequency methods and full-wave numerical simulations for typical edge diffraction structures and complex coated targets, the proposed method supports efficient and physically interpretable edge diffraction SC characterization, supporting physics-based analysis of target scattering responses.