A Hybrid FEBI-PO Method for Large-Scale Electromagnetic Scattering from Targets with Locally Complex Structures

This paper presents an iterative hybrid finite element boundary integral and physical optics (FEBI-PO) method for efficient electromagnetic scattering analysis of electrically large targets that contain locally complex structures. The key idea is to assign as much of the perfectly conducting exterior surface as possible to the physical optics (PO) region while retaining the FEBI formulation in the geometrically and materially complex region. This decomposition reduces the number of boundary integral unknowns associated with the finite element boundary integral (FEBI) subproblem. The disturbed excitation produced by PO currents is further accelerated through an auxiliary matrix-vector product combined with the multilevel fast multipole algorithm (MLFMA). Numerical examples involving an inhomogeneous cavity on a large platform and a ship model with an inhomogeneous cabin show that the proposed method preserves the acceptable accuracy compared with full-wave reference solutions while reducing the computational cost. The method is therefore suitable for scattering from targets with locally complex structures.