12 Result(s)
within
J. R. Sambles
Science, Humanities and Social Sciences, multidisciplinary
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Article
Open AccessMicrowave demonstration of Purcell effect enhanced radiation efficiency
We experimentally demonstrate a Purcell effect-based design technique for improved impedance matching, and thus enhanced the reflection coefficient from a small microwave emitter. Using an iterative process ce...
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Open AccessTailoring the refractive index of impedance-matched ferrite composites
Independent control of the magnetic and electric properties of two-part and three-part ferrite composites is demonstrated through variation of particle size and volume fraction of ferrite inclusions. This prov...
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Article
Open AccessSlow acoustic surface modes through the use of hidden geometry
The acoustic surface modes supported by a partly covered periodic meander groove structure formed in an assumed perfectly rigid plate are investigated. This allows one to create a slower acoustic surface wave ...
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Article
Open AccessSurface wave reflection from a metasurface termination
The reflection coefficient of a microwave surface wave incident at the termination of a metasurface is explored. Two different surface types are examined. One is a square array of square metallic patches on a ...
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Article
Open AccessThe waveguiding of sound using lines of resonant holes
The dispersion of an acoustic surface wave supported by a line of regularly spaced, open ended holes in an acrylic plate, is characterised by precise measurement of its localised acoustic fields. We illustrate...
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Article
Open AccessOmnidirectional surface wave cloak using an isotropic homogeneous dielectric coating
The field of transformation optics owes a lot of its fame to the concept of cloaking. While some experimental progress has been made towards free-space cloaking in three dimensions, the material properties req...
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Open AccessDirect observation of negative-index microwave surface waves
Waves propagating in a negative-index material have wave-front propagation (wavevector, k) opposite in direction to that of energy flow (Poynting vector, S). Here we present an experimental realisation at microwa...
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Article
Open AccessThe Effect of Rotational Disorder on the Microwave Transmission of Checkerboard Metal Square Arrays
The effect of rotational disorder on the microwave transmission through thin metallic checkerboard arrays has been experimentally studied. Broad resonant features below the onset of diffraction, attributed to ...
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Open AccessPolarization conversion from a thin cavity array in the microwave regime
Linearly polarized microwave radiation is shown to have its plane of polarization converted to the orthogonal state upon reflection from an ultrathin (λ/25) cavity array. The structure benefits from an uncompl...
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Article
Now you see it — now you don't
The dazzling iridescence seen in some hummingbirds1 and tropical butterflies2 arises from natural optical phenomena, the brightest of which originate in nanoscale structures that produce ultra-high reflectivity a...
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Article
Colour mixing in wing scales of a butterfly
Green coloration in the animal kingdom, as seen in birds' feathers and reptile integument, is often an additive mixture of structurally effected blue and pigmentary yellow1. Here we investigate the origin of the ...
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Article
Melting of Very Small Particles during Evaporation at Constant Temperature
THE dependence of the melting point of small solid particles on their size is implicit in the work of J. J. Thomson1 on the effect of size on phase equilibria. It has been shown that large depressions of melting ...
