An efficient FDTD algorithm with isotropic numerical dispersion on an overlapped lattice

We develop a second order algorithm for electromagnetics on an overlapped discrete lattice and compare the results with the standard Yee algorithm (1966). The algorithm maintains the locality and simplicity of the Yee algorithm while improving on errors introduced by numerical dispersion. In addition, the algorithm is stable for time steps larger than those required for the Yee algorithm. For a given physical problem and a given error bound, the algorithm is shown to require approximately half the memory of the Yee algorithm and only one half to one third the computation time due to its improved isotropic numerical dispersion and increased time step.