Finite-difference time-domain (FDTD) is a computational technique for electrodynamics modeling. The FDTD method uses a grid-based differential time-domain numerical modeling method. Time-dependent Maxwell's equations (in partial differential form) are discretized into space and time partial derivatives. By stepping in time, the resulting finite-difference equations are solved for each spatial volume. First the electric field (E) vector components in each volume of space are solved at a given instant in time. The magnetic field (H) vector components in the same spatial volume are then solved at the next instant in time. The process is repeated until the desired transient or steady-state electromagnetic field behavior is fully evolved. For a more extensive description of FDTD see WIkipedia.

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