Efficient numerical evaluation of the electromagnetic scattering from arbitrarily-shaped objects by using the Dirichlet-to-Neumann map

This paper presents an efficient technique to evaluate the scattering in the near field zone, based on the Dirichlet-to-Neumann map. Such a map allow to truncate the computational domain from an infinite one to a finite one. Specifically, it introduces an exact boundary condition on the truncated computational domain rather then an approximate one as it happens when using classical absorbing boundary conditions. Moreover, the boundary condition is exact regardless the size of the truncation domain that, in principle, may be chosen coincident with the boundary of the scatterer. Test cases demonstrate the accuracy and the computational advantage of the proposed technique. Also, a case-study referring to a scatterer of “complex” geometry is considered.