72 research outputs found
Coupled-wave surface-impedance analysis of extraordinary transmission through single and stacked metallic screens
In this paper we present an efficient Coupled-wave surface-impedance method
for the analysis of extraordinary optical transmission (EOT) through single and
stacked realistic metallic screens under normal and oblique incidence,
including possible dielectric interlayers. The proposed theory is valid for the
complete frequency range where EOT has been reported, including microwaves and
optics. Electromagnetic simulations validate the results of the model, which
allows for a fast and accurate characterization of the analyzed structures
Dissipation Factors of Spherical Current Modes on Multiple Spherical Layers
Radiation efficiencies of modal current densities distributed on a spherical
shell are evaluated in terms of dissipation factor. The presented approach is
rigorous, yet simple and straightforward, leading to closed-form expressions.
The same approach is utilized for a two-layered shell and the results are
compared with other models existing in the literature. Discrepancies in this
comparison are reported and reasons are analyzed. Finally, it is demonstrated
that radiation efficiency potentially benefits from the use of internal volume
which contrasts with the case of the radiation Q-factor.Comment: 5 pages, 5 figure
Experimental demonstration of a mu=-1 metamaterial lens for magnetic resonance imaging
In this work a mu=-1 metamaterial (MM) lens for magnetic resonance imaging
(MRI) is demonstrated. MRI uses surface coils to detect the radiofrequency(RF)
energy absorbed and emitted by the nuclear spins in the imaged object. The
proposed MM lens manipulates the RF field detected by these surface coils, so
that the coil sensitivity and spatial localization is substantially improved.
Beyond this specific application, we feel that the reported results are the
experimental confirmation of a new concept for the manipulation of RF field in
MRI, which paves the way to many other interesting applications.Comment: 9 pages, 3 figure
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