A hybrid BEM–PO method with adaptive domain decomposition for 3D electromagnetic scattering analysis

This paper presents a hybrid Boundary Element Method-Physical Optics framework with adaptive domain decomposition (H-BEM–PO-ADD) for three-dimensional electromagnetic scattering analysis from perfectly conducting structures. The proposed approach combines full-wave BEM modeling with high-frequency PO approximations within a unified formulation, enabling different surface regions to be treated according to their local physical and geometrical characteristics. A physics-informed adaptive partitioning strategy based on curvature, illumination, electrical size, and interaction considerations is introduced to systematically assign BEM or PO treatment without relying on fixed or heuristic domain partitions. The effectiveness of the method is demonstrated through representative engineering-oriented scattering examples, including an electrically large PEC plate and a PEC dihedral reflector. Numerical results show that the hybrid approach captures diffraction and multiple-scattering effects not accounted for by conventional PO, leading to consistent and physically meaningful differences in the computed radar cross-section responses. The proposed framework provides a flexible and extensible foundation for large-scale electromagnetic scattering analysis and can be naturally extended to other hybrid modeling strategies and more complex geometries.