Abstract
We demonstrate experimentally the double-negative (epsilon < 0, micro < 0) transmission band of a one-dimensional metamaterial structure under normal-to-plane propagation in the microwave regime. The structure consists of stacked bilayers of metal cutwire and wire pairs, which are separated by a thin dielectric layer. The existence of the negative index of refraction is inferred from the transmission and phase spectra obtained by using multilayer metamaterial samples. Another metamaterial structure incorporating non-magnetic (electrically shorted) cutwire pairs does not exhibit the corresponding transmission band, which supports the true left-handed behavior of the metamaterial.
Highlights
We have been long accustomed to the apparent fact that magnetism and negative permittivity (ε < 0 associated with the plasmons) in metals are similar in nature with two siblings that have been separated forever: the former occurring only at frequencies below MHz, whereas the latter resides in the THz regime and beyond
It was demonstrated in the split ring resonator (SRR)-wire type composite metamaterials” (CMMs) that when an electromagnetic wave that has a frequency within the left-handed transmission band propagates in the CMM, the acquired phase shift is negative, that is, the phase decreases [24]
We investigated the transmission and phase spectrum of a composite metamaterial (CMM) that was designed for normal-to-plane propagation
Summary
We have been long accustomed to the apparent fact that magnetism (in particular, diamagnetism characterized by negative permeability, μ< 0) and negative permittivity (ε < 0 associated with the plasmons) in metals are similar in nature with two siblings that have been separated forever: the former occurring only at frequencies below MHz, whereas the latter resides in the THz regime and beyond. The subject remained stored away until recently when Pendry et al took a pioneering approach in “constructing” these materials artificially They have shown that (i) a periodic metallic wire structure can support plasmons with extremely low cut-off frequencies (e.g. down to MHz) so that negative permittivity response can be obtained without being suppressed by the dispersion at low frequencies [2]; (ii) a metallic structure in the shape of concentric split rings can exhibit a magnetic resonance under an axially applied AC magnetic field, and associated with this, negative permeability at extremely high frequencies (above MHz) [3]. Soukoulis et al investigated metamaterials based on cutwire/wire pairs [18], and H-shaped metallic wires [19] under plane-normal propagation, which exhibit a negative index of refraction at microwave frequencies obtained by the retrieval procedure from a single layer of metamaterial Another design consisting of two metal layers perforated by periodic array of holes is proposed and demonstrated at 1.5 μm wavelength [20,21,22].
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