An improved finite-difference time-domain (FDTD) scheme is presented to simulate wave propagation in general Davidson-Cole media.Four improvements are made in this paper:(1)extending to media with multiple relaxation times from ones with single relaxation time;(2)extending to magnetic media from nonmagnetic ones;(3)preserving the term of static ionic conductivity in the Davidson-Cole model;(4)supplementing an example for a three-dimensional (3D) problem.The main difficulty in this scheme is appearance of fractional derivatives.Firstly, the complex permittivity of the medium may be approximated by the Padé polynomials;then, a set of auxiliary differential equations (ADEs) of integer order are derived by the inverse Fourier transform (IFM), this difficulty is thus circumvented.The feasibility and validity of the presented scheme is preliminarily demonstrated by the results and analyses of several examples.
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2015, Vol. 43 
