NUMERICAL PROPERTIES OF STAGGERED FINITE-DIFFERENCE SOLUTIONS OF MAXWELLS EQUATIONS FOR GROUND-PENETRATING RADAR MODELING

Accurate modeling of electromagnetic wave propagation in conducting me dia is important for the further development of ground-penetrating rad ar technologies. Numerical stability and dispersion criteria are deriv ed here for two common 1-D finite-difference solutions of Maxwell's eq uations. In one finite-difference scheme one-sided differences are use d to approximate the conducting term and in the other centered differe nces are employed. Stability is governed by the well-known Courant cri terion. In addition there is a stability condition controlling the dif fusive aspects of wave propagation for the one-sided difference scheme . It is found that the centered difference approximation has significa ntly better stability and dispersion characteristics. For the centered scheme, the well-known spatial sampling criteria for the non-conducti ng case are found to be valid for conducting media. The results are te sted and illustrated using 1-D synthetic radargrams.