379 research outputs found
Physical Insight into the 'Growing' Evanescent Fields of Double-Negative Metamaterial Lenses Using their Circuit Equivalence
Pendry in his paper [Phys. Rev. Lett., 85, 3966 (2000)] put forward an idea
for a lens made of a lossless metamaterial slab with n = -1, that may provide
focusing with resolution beyond the conventional limit. In his analysis, the
evanescent wave inside such a lossless double-negative (DNG) slab is 'growing',
and thus it 'compensates' the decaying exponential outside of it, providing the
sub-wavelength lensing properties of this system. Here, we examine this debated
issue of 'growing exponential' from an equivalent circuit viewpoint by
analyzing a set of distributed-circuit elements representing evanescent wave
interaction with a lossless slab of DNG medium. Our analysis shows that, under
certain conditions, the current in series elements and the voltage at the
element nodes may attain the dominant increasing due to the suitable resonance
of the lossless circuit, providing an alternative physical explanation for
'growing exponential' in Pendry's lens and similar sub-wavelength imaging
systems.Comment: 7 pages, 2 figures, 1 table, submitted to IEEE Transactions on
Antennas and Propagatio
'Growing Evanescent Envelopes and Anomalous Tunneling' in Cascaded Sets of Frequency-Selective Surfaces in Their Stop Bands
The presence of wave tunneling and the 'growing evanescent envelope' for
field distributions in suitably designed, periodically layered stacks of
frequency selective surfaces (FSS) is discussed in this paper. Here it is shown
that a setup completely different completely different from the Pendry's lens
allows an analogous buildup of evanescently modulated waves. In particular, it
is shown how an interface resonance phenomenon similar to the one present at
the interface between metamaterials with oppositely signed constitutive
parameters may be induced by a proper choice of the periodicities of the FSS
stacks and the geometrical properties of these surfaces. The analysis is
performed through an equivalent transmission-line approach, and some physical
insights into this phenomenon are presented. Salient features, such as the
complete wave tunneling through the pair of cascaded FSS, each operating at its
bandgap, are presented and discussed.Comment: 5 pages, 2 figures, submitted to Physical review
Metamaterials with Negative Permittivity and Permeability: Background, Salient Features, and New Trends
Here we first present a brief background and the history of complex media, in particular the materials with negative permittivity and permeability, and then we discuss some of the salient electromagnetic features of these metamaterials. This is followed by description of some of the ideas regarding potential future applications of these metamaterials in devices and components, along with physical remarks and intuitive justification
An Idea for Thin Subwavelength Cavity Resonators Using Metamaterials With Negative Permittivity and Permeability
In this letter, we present and analyze theoretically some ideas for thin one-dimensional (1-D) cavity resonators in which a combination of a conventional dielectric material and a metamaterial possessing negative permittivity and permeability has been inserted. In this analysis, it is shown that a slab of metamaterial with negative permittivity and permeability can act as a phase compensator/conjugator and, thus, by combining such a slab with another slab made of a conventional dielectric material one can, in principle, have a 1-D cavity resonator whose dispersion relation may not depend on the sum of thicknesses of the interior materials filling this cavity, but instead it depends on the ratio of these thicknesses. In other words, one can, in principle, conceptualize a 1-D cavity resonator with the total thickness far less than the conventional λ/2. Mathematical steps and physical intuitions relevant to this problem are presented
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