This work presents an accurate finite‐difference time‐domain (FDTD) dispersive modeling of concrete materials with different water/cement ratios in 50 MHz to 1 GHz. A quadratic complex rational function (QCRF) is employed for dispersive modeling of the relative permittivity of concrete materials. To improve the curve fitting of the QCRF model, the Newton iterative method is applied to determine a weighting factor. Numerical examples validate the accuracy of the proposed dispersive FDTD modeling.

Recently, based on a quadratic complex rational function, a simple and accurate finite-difference time-domain algorithm was introduced for the study of electromagnetic wave propagation in dispersive media. It is of great necessity to investigate the numerical stability of the quadratic complex rational function-finitedifference time-domain to fully utilize this finite-difference time-domain algorithm. In this work, using the von Neumann method with the Routh-Hurwitz criterion, the numerical stability conditions of the quadratic complex rational function-finitedifference time-domain are investigated. It is shown that the numerical stability conditions of the quadratic complex rational function-finite-difference time-domain are not same as those of the conventional finite-difference time-domain schemes.

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