Equivalent-Circuit Model with Retarded Electromagnetic Coupling for Meta-Atoms of Wired Metallic Spheres

Katsuya OHISHI  Takashi HISAKADO  Tohlu MATSUSHIMA  Osami WADA  

IEICE TRANSACTIONS on Electronics   Vol.E101-C   No.12   pp.923-930
Publication Date: 2018/12/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E101.C.923
Type of Manuscript: PAPER
Category: Microwaves, Millimeter-Waves
metamaterial,  meta-atom,  equivalent-circuit model,  retardation,  radiation,  electromagnetic coupling,  

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This paper describes the equivalent-circuit model of a metamaterial composed of conducting spheres and wires. This model involves electromagnetic coupling between the conductors, with retardation. The lumped-parameter equivalent circuit, which imports retardation to the electromagnetic coupling, is developed in this paper from Maxwell's equation. Using the equivalent-circuit model, we clarify the relationship between the retardation and radiation loss; we theoretically demonstrate that the electromagnetic retardation in the near-field represents the radiation loss of the meta-atom in the far-field. Furthermore, this paper focuses on the retarded electromagnetic coupling between two meta-atoms; we estimate the changes in the resonant frequencies and the losses due to the distance between the two coupled meta-atoms. It is established that the dependence characteristics are significantly affected by electromagnetic retardation.