The inclusion of fringing capacitance and inductance in FDTD for the robust accurate treatment of material discontinuities

The analysis of structures which contain sharp material discontinuities using the FDTD method but without resorting to a very fine mesh, although much researched, has not yet been definitively solved. In this paper the fringing fields associated with the discontinuities are dealt with by adjusting the permittivity and permeability assigned to the field nodes which are immediately adjacent to the discontinuities. This method is shown to be effective for a variety of structures and to be without the problems of violating energy or divergence conservation.