A generalized nondiagonally anisotropic perfectly matched layer for wide-angle absorption in finite element electromagnetic scattering analysis

A generalization of the concept of the anisotropic perfectly matched layer is proposed in this paper. The new PML has a nondiagonal symmetric tensor anisotropy. Through the investigation of its properties, it is proven that by an appropriate choice of its parameters, the PML can serve as a wide-angle, reflectionless absorbing layer for electromagnetic scattering analysis. In other words, it can efficiently absorb waves of grazing incidence. Hence, this kind of PML is suitable for the analysis of electrically large structures, since it can be placed close to the scatterer and in a conformal way. The efficiency of the generalized PML is investigated via an analytical approach and a finite element implementation with higher order Whitney elements.