A Collocated 3-D HIE-FDTD Scheme With PML

This letter proposes a novel hybrid implicit-explicit finite-difference time-domain method with collocation in the direction of implicitization. In this direction, the method features increased accuracy, the reason being twofold: 1) the applied combination of interpolations and differentiations preserves second-order accuracy upon nonuniform discretization and 2) material boundaries are more accurately approximated by the grid. The method's stability and accuracy are verified by a microstrip line example. An appropriate PML is included.