Development of broadband parametric permittivity model of dielectric absorbing material for time-domain electromagnetic wave simulation

In this paper, a two-variable multi-pole Debye relaxation model with additional static conductive term is proposed to model complex permittivity of expanded polystyrene mixed with graphite powder obtained from the measured data. This data was available in the frequency range 0.4–5 GHz and the carbon content range 2–30 kg/m3. The parameters of the proposed model are empirically modeled as a linear and quadratic function of carbon content. It is shown that using the proposed model a time domain calculation of broadband characteristics of wave absorbers containing this composite material is enabled. To evaluate the proposed model for a time domain broadband calculation, numerical simulations of the wave absorbers with different structures (planar and pyramid) are performed by the finite-different time-domain (FDTD) method. The results of the simulations are compared with those obtained by other techniques and good agreement is obtained. © 2018 The Institute of Electrical Engineers of Japan.