A FICTITIOUS DOMAIN METHOD FOR CONFORMAL MODELING OF THE PERFECT ELECTRIC CONDUCTORS IN THE FDTD METHOD

We present a fictitious domain method to avoid the staircase approxima tion in the study of perfect electric conductors (PEC) in the finite-d ifference time-domain (FDTD) method. The idea is to extend the electro magnetic field inside the PEC and to introduce a new unknown, the surf ace electric current density to ensure the vanishing of the tangential components of the electric field on the boundary of the PEC. This req uires the use of two independent meshes: a regular three-dimensional ( 3-D) cubic lattice for the electromagnetic field and a triangular surf ace-patching for the surface electric current density. The intersectio n of these two meshes gives a simple coupling law between the electric field and the surface electric current density. An interesting proper ty of this method is that it provides the surface electric current den sity at each time step. Furthermore, this method looks like FDTD with a special model for the PEG. Numerical results for several objects are presented.