Lossy dielectrics in FDTD

The finite-difference time-domain (FDTD) method easily includes materials with constant values of permittivity and conductivity. However, most lossy dielectrics are described over a band of frequencies by a constant complex permittivity. For a transient FDTD calculation, constant real permittivity and conductivity values provide a poor approximation for such a material. Frequency-dependent FDTD can provide a better approximation to a constant complex permittivity over a band of frequencies. The article provides a simple approach for determining the calculation parameters and illustrates the resulting improvement in accuracy.>