Extraction of Electromagnetic Parameters of Metamaterials Based on the State-Space Approach

This paper deals with the introduction of an approach for the electromagnetic characterization of metamaterials based on the state space approach. The state space approach is commonly used to deal with the problems of plane wave scattering from planar layered media، but its application in inverse problems has remained an almost untouched topic in the literature. The proposed method is based on the state transition matrix and its properties which allows avoiding nonlinearity and complexity of the problem. The main difference with respect to other well-established retrieval procedures based on the use of the scattering parameters relies on the direct computation of the transfer matrix of the slab as opposed to the conventional calculation of the propagation constant and impedance of the modes supported by the medium. To validate the proposed method، constitutive parameters of a metamaterial structure are retrieved at microwave frequencies. The results show that the proposed method is robust and reliable.