Numerical analysis of scattering from cylindrical structures coated by layers having inhomogeneity in both radial and azimuthal directions

In this study, the problem of electromagnetic scattering from cylindrical structures with multi-layered coating having inhomogeneity in both radial and azimuthal directions is investigated. The core of the structure may be perfect electric conductor, perfect magnetic conductor, perfect electromagnetic conductor, impedance surface, dielectric or metamaterial. The previous investigations have been restricted to a special case, for example, coatings with only radial inhomogeneity, normal incidence etc. Moreover, in these investigations only single layer coatings are considered and the analysis is based on modelling inhomogeneous coating by homogeneous layers. However, in this study, for the first time, electromagnetic scattering from cylindrical structures coated by multilayered inhomogeneous coating is considered in the most general case for any arbitrary number of layers, incident angle and polarisation. The analysis is based on finite difference method which is a common method in solving engineering electromagnetic problems and the inhomogeneous coating is not approximated by homogeneous layers. The validity of the proposed method is verified through some comprehensive examples. Comparing the results of the proposed method with exact solutions and the results obtained from other commonly used methods in the literature, it is confirmed that the method is simple, fast, accurate and valid for all inhomogeneous layers with continuous electromagnetic profiles.