Analysis of Uniaxial Multilayer Cylinders Used for Invisible Cloak Realization

Uniaxial multilayer cylinder cloaks have recently been proposed to prevent scattering of electromagnetic waves. These cloaks are based on spatial variation of constitutive parameters within the structure by means of metamaterials. A mathematical description of invisibility in such cloaks is provided. The analysis approach is based on modal analysis of cylindrical multilayer structures. In order to analyze structures with arbitrary number of layers, an algorithm to calculate spectral-domain Green´s functions of uniaxial multilayer structures has been developed. The results show that the recently introduced metamaterial cloaks with reduced variation of constitutive parameters can decrease the total scattering width up to a factor of three, but only in a narrow frequency band due to dispersion in the filling material. Furthermore, it is shown that in the analyzed structures already 6 layers of constant permittivity and permeability approximate well the continuous dependence of constitutive parameters.