Penetration of Microwaves Through Dispersive Concrete Using a Three- Dimensional Finite-Difference Time-Domain Code

摘要

In this paper, we present a new formulation of a three-dimensional Finite-Difference Time-Domain (FDTD) algorithm that is applicable for studying the penetration of microwave pulses in conductive and dispersive materials, such as concrete. We investigate the effects of microwaves penetrating into conductive and dispersive concrete using the newly formulated algorithm incorporated into a three-dimensional FDTD code. Because of the dispersive properties of concrete, both conductivity and polarization terms are taken to be frequency-dependent. We model the electric polarization terms and the electric conductivity to exhibit linear dispersive behavior via first-order, time- dependent, electric susceptibility and conductivity functions. Sample one- dimensional FDTD calculations show that the penetration of wide-band and ultrawide-band microwave pulses must be simulated using the fully dispersive FDTD algorithm to obtain the proper response from dispersive concrete. On the other hand, the use of the fully dispersive FDTD algorithm is not essential in simulating the penetration of narrow-band microwave pulses through concrete because of the non-dispersive nature of the narrow-band (single frequency) effect.