Stability and Phase Error Analysis of FD-TD in Dispersive Dielectrics

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Abstract

Four FD-TD extensions for the modeling of pulse propagation in Debye or Lorentz dispersive media are analyzed through studying the stability and phase error properties of the coupled difference equations corresponding to Maxwell's equations and to the equations for the dispersion. For good overall accuracy we show that all schemes should be run at their Courant stability limit, and that the timestep should finely resolve the medium timescales. Particularly, for Debye schemes it should be at least [formula omtted], while for Lorentz schemes it should be At = 10-2t, where [formula omtted] is a typical medium relaxation time. A numerical experiment with a Debye medium confirms this. We have determined that two of the discretizations for Debye media are totally equivalent. In the Lorentz medium case we establish that the method that uses the polarization differential equation to model dispersion is stable for all wavenumbers, and that the method using the local-in-time constitutive relation is weakly unstable for modes with wavenumber k such that [formula omtted].

Original languageEnglish (US)
Pages (from-to)62-69
Number of pages8
JournalIEEE Transactions on Antennas and Propagation
Volume42
Issue number1
DOIs
StatePublished - Jan 1994
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering

Keywords

  • Dispersive media
  • RF dosimetry
  • algorithm stability and phase error
  • bioelectromagnetics
  • finite-difference time-domain method

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