An Efficient FDTD Algorithm for Calculating Low-Frequency Transmission Characteristics of Multilayer Metal Meshes

To analyze the transmission characteristics of multilayer metal mesh structures, a significant amount of memory and calculation time are frequently needed for the construction of models with fine structures for numerical calculations. In this article, the scheme of single-layer homogeneous media equivalent multilayer metal mesh structures is proposed. First, the permittivity of given parameters (the diameter of the metal wire, the aperture size, and the spacing between the mesh layers) is determined by combining the analytical model of shielding effectiveness calculation of multilayer metal meshes with the genetic algorithm. Then, based on the analysis of the variation characteristics of the polarizability function of equivalent medium with frequency, a linear dispersive model of equivalent dielectric is proposed, which is appropriate for the analysis of low-frequency wave-propagation characteristics of multilayer metal meshes. Finally, the recursive convolution (RC) method is adopted to deal with the transformation of the polarizability function from the frequency domain to the time domain, and the recursive calculation formula of the RC-finite-difference time-domain (RC-FDTD) method is given. The numerical results demonstrate that the proposed method costs less memory and time compared with the typical accurate modeling scheme.