Abstract-We introduce and investigate the applications of double zero (DZR) metamaterials (having the real parts of permittivity and permeability equal to zero) as radar absorbing materials (RAMs). We consider a perfectly electric conductor (PEC) plate covered by several layers of DZR metamaterial coatings under an oblique plane wave incidence of arbitrary polarization. Several analytical formulas are derived for the realization of zero reflection from such structures. The angle of reflection in the DZR metamaterials becomes complex, which leads to the dissociation of the constant amplitude and equiphase planes. Then several examples of the applications of DZR metamaterials (in nondispersive and dispersive conditions) as RAMs and zero reflection coatings are provided. The characteristics and parameters of the DZR metamaterial media are determined in each case. The method of least squares is used to optimize the DZR coatings for the minimization of reflected power, which uses the combination of genetic algorithm and conjugate gradient method (GA-CG) to benefit from their advantages and avert their short comings.

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Bi-anisotropic materials have enormous and interesting applications in electromagnetic (EM) engineering. In this study, based on the state space concept, an exact and rigorous analysis of EM propagation and scattering from multilayer bi-anisotropic cylindrical structures of the general case is proposed. In comparison to the other commonly used methods in the literature, the presented method reveals a faster and more accurate analytical framework. The similar works mostly presented approximated and numerical methods for the analysis of cylindrical structures containing bi-isotropic and/or anisotropic materials as special bi-anisotropic cases. Throughout the study, the geometrical specifications and the EM excitations are chosen based on practical considerations. Since the multilayer composite is practical especially for the realization of the inhomogeneous material, the proposed approach is applied to analyze inhomogeneous bi-anisotropic cylindrical structures with more degrees of freedom in manipulation of EM waves. Our results depict an excellent conformity to the other possible solutions to compute scattering from bi-anisotropic cylindrical configurations. The mentioned comprehensiveness is one of the main advantages of our work. The suggested approach can be used as a basic step for future research related to the analysis of forward and inverse scattering problems of practical types of cylindrical structures made by complex media.

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In this paper, the state space method is developed for analysis of the scattering of radially inhomogeneous cylindrical structures. The developed technique is based on obtaining and using the state transition matrix of cylindrical layers. The most valuable and interesting property of the presented method is its systematic approach, allowing one to easily apply this method to any types of cylindrical inhomogeneous media and simply implement it in a programming language supporting matrix manipulations. The validity of the presented method as well as the correctness of the formulation is achieved by providing some numerical examples and comparing the obtained results with the results of previously published works.