An improved time domain finite element-boundary integral scheme for electromagnetic scattering from 3-D objects

This paper proposes an improved time domain finite element-boundary integral scheme for 3-D scattering from arbitraryshaped objects. The proposed scheme, which uses only one auxiliary boundary, is more efficient than the one reported in the literature that uses two auxiliary boundaries. While preserving the sparseness and symmetry of the finite element matrices, the proposed scheme reduces the computational domain for the finite elements. A major difficulty, here, is the treatment of the singularity of Green's function arising from this scheme. To overcome this problem, the contribution of singular point is computed analytically, and equivalent transformation technique is also included to reduce the integrals' singularity. And, a remedy is presented for the numerical error encountered in the course of the equivalent transformation, which essentially may be attributed to the inherent routine with the time domain finite element-boundary integral method. The validity and accuracy of the hybrid scheme are verified by numerical tests.