A general approach for the development of unsplit-field time-domain implementations of perfectly matched layers for FDTD grid truncation

It is shown that the anisotropic perfectly matched medium, proposed recently for the construction of reflectionless absorbing boundaries for differential equation-based electromagnetic simulations in unbounded domains, can be made equivalent to the Chew-Weedon perfectly matched medium developed from a modified Maxwell's system with coordinate stretching. Consequently, despite the apparently nonphysical coordinate stretching, Chew-Weedon's formulation, with an appropriate definition of the involved electric and magnetic fields, is merely an alternative mathematical form of Maxwell's system in an anisotropic medium. Finally, a more convenient time-domain implementation of the perfectly matched layer without splitting of the field components is derived.