A novel analytical method for analysis of electromagnetic scattering from inhomogeneous spherical structures using duality principles

TL;DR

This paper introduces a new analytical method based on duality principles to analyze electromagnetic scattering from inhomogeneous spherical structures, simplifying complex spherical problems into planar ones and enabling the study of gradient index lens antennas.

Contribution

The paper presents a novel duality-based analytical approach for EM scattering analysis of radially inhomogeneous spheres, applicable to various inhomogeneity profiles and structures.

Findings

Validated the approach with a comprehensive example.

Successfully analyzed a gradient index lens antenna.

Demonstrated the method's ability to simplify complex spherical problems.

Abstract

In this article, a novel analytical approach is presented for the analysis of electromagnetic (EM) scattering from radially inhomogeneous spherical structures (RISSs) based on the duality principle. According to the spherical symmetry, similar angular dependencies in all the regions are considered using spherical harmonics. To extract the radial dependency, the system of differential equations of wave propagation toward the inhomogeneity direction is equated with the dual planar ones. A general duality between electromagnetic fields and parameters and scattering parameters of the two structures is introduced. The validity of the proposed approach is verified through a comprehensive example. The presented approach substitutes a complicated problem in spherical coordinate to an easy, well posed, and a previously solved problem in planar geometry. This approach is valid for all continuously varying inhomogeneity profiles. One of the major advantages of the proposed method is the capability of studying two general and applicable types of RISSs. As an interesting application, a new class of lens antenna based on the physical concept of the gradient refractive index material is introduced. The approach is used to analyze the EM scattering from the structure and validate strong performance of the lens.