Application of the TLM method to the interaction of EM fields with dispersive dielectric bodies

摘要

The application of the symmetric condensed node transmission line matrix method (SCN TLM) to three-dimensional scattering from biological tissue is investigated. To simulate the dispersive nature of biological tissue, a second-order Debye equation of the permittivity in the frequency domain is used in a modified TLM technique. In this technique, the scattering matrix is independent of the dielectric properties of the medium, which are accounted for via lumped equivalent networks or sources connected to the nodes. These equivalent sources are calculated at each time step and included in the scattering procedure of the TLM. Assuming the nondispersive nature of biological tissue, the nondispersive or stub-loaded SCN TLM method is used to obtain the near field data and the specific absorption rate (SAR) distribution. The results of both cases are compared. The modified TLM technique is then applied to a nonhomogeneous and geometrically complex dispersive dielectric body, which is the human head. Two models of the head are used, a simplified model of 209 coarse cells and a refined model of 24552 cells.