Combination of Mls , GA & Cg for the Reduction of RCS of Multilayered Cylindrical Structures Composed of Dispersive Metamaterials
In this paper the electromagnetic wave scattering from multilayered cylindrical structures is studied for a normally incident plane wave with linear (TE or TM), circular and elliptical polarizations. The cylindrical layers may be composed of any combination of dispersive common materials and metamaterials. The addition theorems for the cylindrical waves are used for the EM wave analysis. The objective of this study is to decrease or increase the Radar Cross Section (RCS) in an ultra wide band width. The optimization is based on the Method of Least Squares (MLS), employing a novel combination of the Genetic Algorithm (GA) and Conjugate Gradient (CG), where the global search for the minimization point is performed by GA and the local search is done by CG, which greatly speeds up the search algorithm. The behaviors of various combinations of common materials and metamaterials for reduction of RCS are studied. Furthermore, the procedures for selection of correct signs for metamaterial parameters, namely ε, μ, k and η are presented.