1,721,140 research outputs found
Active loss mitigation and modes in an artificial material made of a 3D-lattice of plasmonic nanoshells
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Dual-Frequency Single- and Dual-Polarization Fabry-Perot Cavity Antennas with a Superstrate Made by a Metamaterial Layer of Paired Conductors
No full textArtificial magnetism and transmission peaks in metamaterials made by pairs of planar conductors
No full textArtificial magnetism and modes at millimeter waves in 3D lattices of titanium oxide microspheres
No full textExploration of advantages and drawbacks of metamaterial leaky-wave antennas
No full textVery recently, the development of highly-directive antennas for broadside radiation has attracted the interest of many researchers, and several structures have been proposed and realized. With respect to other highly-directive structures, planar leaky-wave antennas (LWAs) have the typical advantages of being simple, low-cost, and compatible with planar integration. Conventional planar LWAs may be built in several ways, with dielectric and/or metallic layers. Most of these structures may be viewed as a grounded dielectric slab covered with a “partially reflecting surface” (PRS). A simple source is used to launch a cylindrically propagating set of TM and TE leaky waves. The source can be a horizontal infinitesimal electric or magnetic dipole (representing a finite printed dipole or a narrow slot on the ground plane, respectively), although the radiated pattern and the high-directivity effect mainly depend on the structure and not on the particular source. Although not immediately recognized, recently proposed one-dimensional electromagnetic bandgap structures also fall into this class of antennas.
The recent tremendous interest and research in metamaterials has led to the development of high-directivity antennas using a metamaterial layer (for instance, a grounded layer with a relative permittivity near zero). It can be shown that also such novel antennas are intrinsically LWAs, and hence a comparison with conventional LWAs (in terms of various quantities of interest, such as directivity, bandwidth, power enhancement, efficiency, and physical size) is warranted. In this work, the properties of such metamaterial LWAs will be explored, and comparisons will be made with conventional PRS-based LWAs. It will be shown whether and how the possible use of artificial metamaterial layers may improve the performance of typical LWAs, especially in terms of bandwidth and efficiency
Highly-directive planar leaky-wave antennas: A comparison between metamaterial-based and conventional designs
No full textA comparative study is made of two types of planar leaky-wave antennas. The first type is a “conventional” planar leaky-wave antenna composed of a grounded slab that is covered with a metallic or dielectric partially-reflecting surface, which acts as a leaky parallel-plate waveguide. The second type is a leaky-wave antenna consisting of a grounded metamaterial layer, having either a very low permittivity or permeability. For either type of structure, directive pencil beams at broadside may be produced when the structure is excited with a simple source such as a horizontal electric or magnetic dipole. A high directivity is obtained by the excitation of weakly-attenuated cylindrical leaky waves that propagate radially outward from the source on the planar structure. The comparison is made for the fundamental antenna properties such as broadside directivity, radiated broadside power density, pattern bandwidth, and the attenuation constants of the relevant leaky modes
Enhanced directivity with thinned arrays using Fabry-Perot cavities covered by a partially reflective surface
No full textModeling of Self-Assembled Metamaterials at Optical Frequencies with Incorporated Gain Media
No full textNumerical modeling of nanostructured metamaterials
No full textElectromagnetic and optical properties of metamaterials are collective responses depending on both constituent elements resonant behaviour and their spatial arrangement. In this work we outline an approach for predicting the effective electric and magnetic properties of metamaterials from the scattering response of an individual inclusion decomposed into its spherical wave spectral components. The applicability of the method is demonstrated by analyzing a few sample metamaterial assemblies
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