In this paper, we present a hybrid coordinate FDTD scheme, in which we inse
rt a local conformal coordinate system which conforms with the scatterers i
n a Cartesian coordinate system, when there exists a nonrectangular scatter
er in the Cartesian coordinate system. We propose a new interpolation schem
e in the overlap region to achieve low reflection from the interface betwee
n the built-in and Cartesian regions. The numerical experiment demonstrates
that this scheme has a significant improvement in the staircasing approxim
ation. (C) 2001 John Wiley & Sons, Inc.