Feasibility study of uniaxial structures used for invisible cloak design

The purpose of this paper is to study realization feasibility of the cloak structures where the continuously-varying structure is realized as multilayer structure with the stepwise approximation of the constitutive parameters. In order to do that, the influence of the number of cloak layers is investigated, and it is shown that with only three layers it is possible to obtain a better cloak performance than the Schurig cloak (containing ten layers), and that with ten or more layers one can design a cloak that is practically invisible. These results are obtained by merging the program for analyzing uniaxial cylindrical structures with the global optimization program based on the particle swarm optimization algorithm.