Propagation and Aliasing of High Frequencies in the FDTD Grid

The FDTD method is usually employed below its cutoff frequency, in the region where the propagation of waves is nondissipative and almost free of dispersion. This paper addresses what occurs when arbitrarily high frequencies are coupled to the grid. The solutions of the FDTD equation of dispersion are derived for any frequency, and the aliasing of frequencies is demonstrated. Some solutions which can be used to remove the spurious effects of aliasing are discussed.