An efficient numerical boundary condition for the truncation of finite element meshes for the analysis of electromagnetic scattering by complex bodies

The authors investigate the finite element implementation of a numerical boundary condition which, like the MEI (measured equation of invariance) boundary condition, depends on the location of the boundary node, the geometry of the scatterer, and the polarization of the incident field, and is derived by considering the fields that would be radiated by current sources in the vicinity of the scatterer. This boundary condition can be used for either homogeneous or inhomogeneous scatterers. This method of mesh truncation works well for both propagating and evanescent harmonics, even when the mesh boundary is quite close to the scatterer. Furthermore, it can be enforced on a mesh boundary of arbitrary shape; there is no requirement of a circular or spherical geometry. Numerical results obtained using this technique are presented.<>