38 research outputs found
Meta-molecular devices
We report the development of a new method to both describe and design metamaterials, meta-surfaces and meta-structures in which discrete passive structures are combined into ensembles. We call these structures, meta-atoms and the structures that result are meta-molecules. By using this concept new structures can be designed with a wide range of desirable properties
3-D printed bandpass filters with coupled vertically extruded split ring resonators
The additive manufacturing process of multimaterial extrusion offers performance advantages using functional
materials including conductors while making accessible the third
dimension in the design of electronics. In this work we show that
the additional geometrical freedom offered by this technique can
be exploited for the design and realisation of filters made of
three- dimensional (3D) resonators that exhibit enhanced characteristics. The coupling properties of 3D grounded square split
ring resonators (SRRs) are initially explored. We demonstrate
by simulations and experiments that SRRs with finite height
display significantly stronger coupling compared to equivalent
thin printed circuit structures. The observed trend can be
exploited for designing filters with wider operational bandwidths
for a given footprint, or miniaturized layouts and enhanced
compatibility with fabrication limits for minimum feature size
and spacing without performance degradation. This concept is
demonstrated by presenting results of full-wave simulations for
sample bandpass filters with identical footprint but formed by
coupled 3D square SRRs of different heights, showing that filters
with taller resonators exhibit increasingly wider bandwidths.
Two filter prototypes with centre frequencies at 1.6 GHz and
2.45 GHz are manufactured by multimaterial 3D printing. The
measured characteristics of these prototypes are found to be in
good agreement with numerical simulations taking into account
the effect of the lossier metallic and dielectric materials used in
3D printing and confirm the predicted larger bandwidth of the
filters made of 3D SRRs with marginally higher insertion losses
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Tightly coupled tripole conductor pairs as constituents for a planar 2D-isotropic negative refractive index metamaterial
A metamaterial, arranged by stacking layers of planar constituents suitably shaped to be responsive to arbitrarily linearly polarized incident waves is here shown to exhibit 2D-isotropic effective negative refractive index (NRI). The general concept underlying this metamaterial design consists of closely pairing two metallic particles to accomplish, as a result of their tight coupling, both symmetric and antisymmetric resonance modes, whose proper superposition can lead to an effective negative refraction response. The proposed structure is composed by layers of periodically arranged pairs of face coupled loaded tripoles printed on the opposite sides of a single dielectric substrate. Through a comprehensive characterization of the transmission properties of such metamaterial, together with the analysis of its dispersion diagram, conclusive evidence that the medium exhibits effective NRI properties as well as good impedance matching to free space is provided. We also describe some guidelines to design the proposed metamaterial with a prescribed operational frequency bandwidth, dependently on the structure parameters. (C) 2009 Optical Society of Americ
Recommended from our members
Tightly coupled tripole conductor pairs as constituents for a planar 2D-isotropic negative refractive index metamaterial
A metamaterial, arranged by stacking layers of planar constituents suitably shaped to be responsive to arbitrarily linearly polarized incident waves is here shown to exhibit 2D-isotropic effective negative refractive index (NRI). The general concept underlying this metamaterial design consists of closely pairing two metallic particles to accomplish, as a result of their tight coupling, both symmetric and antisymmetric resonance modes, whose proper superposition can lead to an effective negative refraction response. The proposed structure is composed by layers of periodically arranged pairs of face coupled loaded tripoles printed on the opposite sides of a single dielectric substrate. Through a comprehensive characterization of the transmission properties of such metamaterial, together with the analysis of its dispersion diagram, conclusive evidence that the medium exhibits effective NRI properties as well as good impedance matching to free space is provided. We also describe some guidelines to design the proposed metamaterial with a prescribed operational frequency bandwidth, dependently on the structure parameters. (C) 2009 Optical Society of Americ