Frequency dispersion in chiral and omega media: an approximate theoretical model

Addresses the problem of modeling constitutive parameters of artificial isotropic chiral and bianisotropic omega composites. Magnetoelectric interaction in these composites is provided by chiral electrically small helices or n-shaped inclusions distributed in a isotropic dielectric or magnetodielectric matrix. The goal is to find a way to predict macroscopic properties of whole composites from the sizes of particles and the inclusion concentration. The authors propose a simple analytical model which leads to explicit relations between scatterers´ configuration and the constitutive parameters. The approach is based on the antenna model of single chiral end omega particles. Each particle is considered as a wire-and-loop structure of appropriate geometry, and antenna theory is used to calculate the polarizabilities. Based on the Maxwell-Garnett model (generalized for arbitrary dyadic polarizabilities in Weiglhofer et al., 1993) the authors study the permittivity, permeability and coupling parameters of composites with particles either randomly distributed or arranged in arrays. The model conforms to basic physical requirements such as the reciprocity theorem and gives proper limiting values at low or high frequencies. Computed curves demonstrate the most typical frequency behaviour of the constitutive parameters of isotropic chiral and bianisotropic omega composites.<>