Stored energy of arbitrary metamaterial inclusions

Abstract

Electromagnetic metamaterials are generally defined and classified in terms of their effective parameters. They are evaluated in the far-field which limits the evaluation of its near field interaction in some applications such as metamaterial inspired design. An alternative approach proposed in this paper is based on the modal stored energy of metamaterial inclusion. This approach is based on the surface current distribution which would address the challenge of metamaterial near-field application. This paper describes a method for quantifying the modal stored energy of arbitrary-shaped metamaterial inclusions based on the theory of characteristic modes. The theory of characteristic modes is independent of excitation, gives good physical insight into the behaviour of an inclusion and would be helpful for near-field application of metamaterials. The modal stored energy approach is also compared with the common effective parameter approach. It shows similarity in terms of the physical and qualitative analysis when far-field assumptions are accounted for. The broadside-coupled split-ring resonator and the S-shaped inclusion are considered. The physical and qualitative analysis based on the modal stored energy approach shows a good agreement with the effective parameter approach.