Z-TRANSFORM THEORY AND THE FDTD METHOD

In implementing the finite-difference time-domain (FDTD) method on mat erials which are dispersive or nonlinear, the relationship between the flux density and the electric field can be the most complicated part of the problem, Because the FDTD method is a sampled time-domain metho d, this relationship can be can be looked upon as a digital filtering problem. The Z transform is typically used in digital filtering and si gnal processing problems, This paper illustrates the use of the Z tran sform in implementing the FDTD method where complicated dispersive or nonlinear materials are involved.