Determination of Effective Constitutive Parameters, Material Boundaries and Properties of SRR-rod and Fishnet Metamaterials by Drude/Lorentz Dispersion Models

摘要

This paper presents two effective extraction methods to fully retrieve effective refractive indices (n), impedances (z), and material properties, such as dielectric permittivity (ε) and permeability (μ) of metamaterials (MMs). The first full extraction method based on the material continuity allows missing results in the strong resonant band where the imaginary part of permittivity or permeability is negative to be retrieved. The second method describes a genetic algorithm and optimization of properly defined goal functions to retrieve the parameters from Drude and Lorentz dispersion models for e and μ, respectively. Proper initial values of the parameters of models and partial retrieved e and μ are also derived for the second method in order to reduce the computation time and prevent the optimization solution from falling into local minimum. Finally, the refractive index, impedance, permittivity, and permeability of two slabs composed of SRR-based and fishnet MMs are retrieved and compared using the proposed methods.