Mixed finite-difference/Whitney-elements time domain (FD/WE-TD) method

A mixed finite-difference/Whitney-elements time-domain (FD/WE-TD) method is proposed for the analysis of transient electromagnetic field problems. The method consists in discretizing the spatial region in two parts composed respectively by structured and unstructured elements. In the structured mesh Maxwell's curl equations are numerically solved by Yee's algorithm while in the unstructured mesh the wave equation is solved in terms of electric field by the WETD method. The proposed method leads to an explicit-implicit solution scheme which is convenient to model curved boundaries and complex configurations without a significant increase of the computational cost with respect to the basic FDTD method. The FD/WE-TD method is a valid alternative of the subgridding algorithms and nonuniform grid models used in the FDTD calculations. The nonphysical wave reflection introduced by the finite elements is calculated for simple canonical configurations.