The Signs of the Imaginary Parts of the Effective Permittivity and Permeability inMetamaterials

摘要

Materials that exhibit negative, real parts of the-permittivity, permeability, and index of refraction have received much attention recently. Generally composed of periodic arrangements of elements with complex shapes these media, referred to as metamaterials, can be made to exhibit various exotic behaviors. In addition, because the frequency response of, these media often scales linearly with the dimensions of the building elements, their effective parameters (e.g., permittivity, permeability, and index of refraction) can be tailored at different frequencies. However, it is often the case that exact analytical expressions describing the effective parameters cannot be formulated analytically due to the complexity- of the particles involved (for example, in the case of split rings resonators (SRRs) or split wires). As a result the effective parameters of these media, such as the permittivity (ε), Permeability (μ), index of refraction (n), and impedance (z ) have often been determined using a technique referred to as the homogenization or retrieval technique [1]. In this technique the effective parameters of the medium are calculated from the numerically simulated or experimentally measured scattering parameters (S-parameters).