Transient simulation using discrete-time representation of generalized frequency-dependent permittivity

A direct method for incorporating frequency-dependent permittivity into an FDTD algorithm is presented in this paper. The frequency-dependent permittivity is represented as a series of modified impulse responses using a non-uniform discrete-time technique. The modified impulse response can be applied within a convolution in FDTD algorithm for general transient analysis. The method presented here is highly accurate and stable, and is suitable for use in quite general cases, especially where the permittivity shows complicated frequency dependence.