Additional Boundary Condition for a Wire Medium Connected to a Metallic Surface

TL;DR

This paper introduces an additional boundary condition for modeling wire media connected to metallic surfaces, enabling accurate homogenization and characterization of their electromagnetic behavior, including extreme anisotropy and impedance surface properties.

Contribution

It derives a new boundary condition considering microstructure effects, improving the homogenization of wire media connected to metallic surfaces.

Findings

Wire medium exhibits extreme optical anisotropy.

The substrate can act as an impedance surface.

Homogenization accuracy is enhanced with the new boundary condition.

Abstract

In this work, we demonstrate that the interaction of electromagnetic waves with a microstructured material formed by metallic wires connected to a metallic surface can be described using homogenization methods provided an additional boundary condition is considered. The additional boundary condition is derived by taking into account the specific microstructure of the wire medium. To illustrate the application of the result, we characterize a substrate formed by an array of tilted metallic wires connected to a ground plane, demonstrating that in such configuration the wire medium behaves essentially as a material with extreme optical anisotropy and that in some circumstances the substrate can be seen as an impedance surface.