A signal processing approach to finite-difference time-domain computations

The FDTD method is used to find numerical solutions to Maxwell´s equations when analytic ones are prohibitive. Brute force approach to the FDTD method requires costly calculation at every point in the solution grid. If the solution is required at only a subset of the domain, then some computing time can be saved by expressing a portion of the grid as an LTI system with inputs and outputs. The output then becomes a convolution of the input with the LTI impulse response. We show how the impulse response is derived from the FDTD algorithm and how a reduction in the computation time is achieved