An improved implementation of nonorthogonal FDTD using triangular fillings

The FDTD algorithm on nonorthogonal grids, which was originally proposed by Holland in 1983, has been proven to have good modeling properties also for oblique or curved boundaries. As it still uses structured grids, however, the mesh generation process is often difficult, and may result in degenerated mesh cells with grid angles near 180/spl deg/. We present the combination of nonorthogonal FDTD with the concept of triangular fillings. The resulting algorithm allows a more general mesh generation, where degenerated cells can usually be easily avoided, without additional computational cost or loss of modeling accuracy.