Finite Element Spectral Integral (FESI) Method for Scattering From an Arbitrary Number of Circular Cylinders With Inhomogeneous Shells

The hybrid finite element spectral integral (FESI) method is developed to solve the radiation and scattering problems of multiple circular cylinders with inhomogeneous shells. The FESI method combines the spectral integral method (SIM) with the finite element method (FEM) to simulate electromagnetic (EM) scattering from inhomogeneities separated by multiple regions of homogeneous spaces. The SIM is extended to multiple circular dielectric cylinders and serves as the exact radiation boundary condition for the FEM to simulate waves in the remaining inhomogeneous regions. This approach eliminates the mesh in any homogeneous domains with circular boundaries and leads to higher efficiency than the traditional FEM. The SIM can achieve 99% accuracy with up to 90% less sampling density than the method of moments (MoM) and has exponential convergence. We present several numerical examples to demonstrate the accuracy and efficiency of the SIM and FESI method.