Realization of a spherical boundary by a layer of wave-guiding medium

TL;DR

This paper introduces a spherical wave-guiding medium that transforms boundary conditions, enabling the realization of D'B' boundaries from DB boundaries, demonstrated through scattering simulations.

Contribution

It extends the concept of wave-guiding media to spherical structures, showing how a quarter-wavelength layer can transform boundary conditions between spherical interfaces.

Findings

A quarter-wavelength layer transforms boundary conditions effectively.

Scattering results match theoretical predictions for various medium parameters.

The method enables practical realization of D'B' boundaries.

Abstract

In this paper the concept of wave-guiding medium, previously introduced for planar structures, is defined for the spherically symmetric case. It is shown that a quarter-wavelength layer of such a medium serves as a transformer of boundary conditions between two spherical interfaces. As an application, the D'B'-boundary condition, requiring vanishing of normal derivatives of the normal components of D and B field vectors, is realized by transforming the DB-boundary conditions. To test the theory, scattering from a spherical DB object covered by a layer of wave-guiding material is compared to the corresponding scattering from an ideal D'B' sphere, for varying medium parameters of the layer.