Robust technique based on transition matrix method to electromagnetic characterisation of anisotropic material

This study presents a parameter retrieval technique based on the state space approach for the electromagnetic characterisation of biaxial anisotropic structures. First, the formulation of a 4 × 4 transition matrix method for the analysis of forward scattering problems is reviewed; then a procedure for the extraction of the constitutive tensor parameters of a biaxial anisotropic medium from the knowledge of reflection and transmission coefficients is implemented. In the proposed retrieval method, scattering parameters are employed for a plane wave incident normally and obliquely on a biaxial anisotropic slab. This characterisation algorithm is based on the state transition matrix and its properties in the biaxial anisotropic layers are presented as two theorems. In this method, it is not necessary to solve directly the wave equation in complex media and then apply the boundary conditions. To demonstrate the validity of the proposed method, the constitutive parameters of two non-dispersive and dispersive biaxial anisotropic slabs at microwave frequencies are retrieved. From the numerical results, one can find out that when the scattering parameters are combined with the properties of a state transition matrix, a robust technique is provided for the parameter retrieval of the anisotropic structures.