Direct calculation of permeability and permittivity for a left-handed metamaterial
TL;DR: In this article, an electromagnetic metamaterial was fabricated and demonstrated to exhibit a "left-handed" (LH) propagation band at microwave frequencies, a situation never observed in naturally occurring materials or composites.
Abstract: Recently, an electromagnetic metamaterial was fabricated and demonstrated to exhibit a “left-handed” (LH) propagation band at microwave frequencies. A LH metamaterial is one characterized by material constants—the permeability and permittivity—which are simultaneously negative, a situation never observed in naturally occurring materials or composites. While the presence of the propagation band was shown to be an inherent demonstration of left handedness, actual numerical values for the material constants were not obtained. In the present work, using appropriate averages to define the macroscopic fields, we extract quantitative values for the effective permeability and permittivity from finite-difference simulations using three different approaches.
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TL;DR: In this paper, two novel resonators were devised which are amendments on commonly used S-shaped resonator and enable a great miniaturization rate, which can avoid magnetoelectric coupling in the artificial constituents that preclude the bianisotropy.
Abstract: Two novel resonators were devised which are amendments on commonly used S-shaped resonator and enable a great miniaturization rate. The symmetrical structure of these inclusions can avoid magnetoelectric coupling in the artificial constituents that preclude the bianisotropy. One of these metamaterials is an integration of continuous wire and an S-shaped-spiral. The other is a structure of SRRs and S-shape resonator with improved electromagnetic coupling and reduced electrical size. Both of them have wide negative refraction passband with low losses. The superior performances of these structures were investigated numerically and experimentally for only normal incidence case and tested through a proper comparison with the S-shaped resonator.
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07 Aug 2002
TL;DR: In this article, a mixture of two or more off-the-shelf materials (air and LTCC) is used to develop a pre-specified relative dielectric constant ranging from 20-100.
Abstract: In this paper, we propose a new way of designing artificial material volumes (or metamaterials), which have pre-specified dielectric constants. We also evaluate the dependency of the resulting dielectric constants on the generated texture and material composition. The design method is based on the mixture of two or more off-the-shelf materials (air and LTCC) to develop a pre-specified relative dielectric constant ranging from 20-100. A key aspect of the mixing approach is its practicality. That is, once the mixing formula is mathematically developed, we can then proceed to manufacture it using standard extrusion, solid free-form fabrication or other techniques. It is important to note that in our approach material mixing occurs at the microscale and the resulting mix leads to a texture rendered by a periodic repetition of a unit cell. This texture is similar to a floor carpet design, but at a much finer scale.
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TL;DR: In this paper, a new type of backward-wave coupled-line directional coupler with complete coupling and broadband, which is composed of a conventional microstrip and a 1D mushroom structure, is proposed.
Abstract: A new type of backward-wave coupled-line directional coupler with complete coupling and broadband, which is composed of a conventional microstrip and a 1D mushroom structure, is proposed. The 1D mushroom structure is employed for a double negative (DNG) transmission line. The coupler exhibits unusual characteristics such as complex propagation. The complex propagation constant of the coupled mode enables strong coupling due to exponential field decay. The performance of the proposed coupler is verified by c- and π-mode analysis, full-wave simulation, and measurement. The measured coupling level of −0.5 dB with 3-dB fractional bandwidth of 35% and high directivity of 30 dB is achieved. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1293–1296, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21622
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Cites background from "Direct calculation of permeability ..."
..., respectively, DNG materials have been researched by many groups [3–5]....
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TL;DR: In this paper, the concept of equivalent material values is validated by large "global" simulations of a wedge structure, and the limitations of this concept are discussed, since in some cases the macroscopic behavior of an LHM cannot be accurately described by equivalent material value.
Abstract: . In order to characterize three-dimensional, left-handed metamaterials (LHM) we use electromagnetic field simulations of unit cells. For waves traveling in one of the main directions of the periodic LHM-arrays, the analysis is concentrated on the calculation of global quantities of the unit cells, such as scattering parameters or dispersion diagrams, and a careful interpretation of the results. We show that the concept of equivalent material values – which may be negative in a narrow frequency range – can be validated by large "global" simulations of a wedge structure. We also discuss the limitations of this concept, since in some cases the macroscopic behavior of an LHM cannot be accurately described by equivalent material values.
5 citations
Cites methods from "Direct calculation of permeability ..."
...The raw ata can be obtained by analytical considerations (Pendry et al., 1999) or measurements (Shelby et al., 2001), or – with increasing importance – by field simulations (Smith et al., 2000; Weiland et al., 2001)....
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TL;DR: A novel framework that involves coupling the Hybrid Embedded Fracture (HEF) scheme with Machine Learning is described and a pure Machine-Learning classifier and Deep-Learning topology design is formulated to deal with the extraction of hierarchical fracture features from low-level to high-level based on Neural-Network layers.
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10,495 citations
TL;DR: In this paper, it was shown that microstructures built from nonmagnetic conducting sheets exhibit an effective magnetic permeability /spl mu/sub eff/, which can be tuned to values not accessible in naturally occurring materials.
Abstract: We show that microstructures built from nonmagnetic conducting sheets exhibit an effective magnetic permeability /spl mu//sub eff/, which can be tuned to values not accessible in naturally occurring materials, including large imaginary components of /spl mu//sub eff/. The microstructure is on a scale much less than the wavelength of radiation, is not resolved by incident microwaves, and uses a very low density of metal so that structures can be extremely lightweight. Most of the structures are resonant due to internal capacitance and inductance, and resonant enhancement combined with compression of electrical energy into a very small volume greatly enhances the energy density at critical locations in the structure, easily by factors of a million and possibly by much more. Weakly nonlinear materials placed at these critical locations will show greatly enhanced effects raising the possibility of manufacturing active structures whose properties can be switched at will between many states.
8,135 citations
TL;DR: A composite medium, based on a periodic array of interspaced conducting nonmagnetic split ring resonators and continuous wires, that exhibits a frequency region in the microwave regime with simultaneously negative values of effective permeability and permittivity varepsilon(eff)(omega).
Abstract: We demonstrate a composite medium, based on a periodic array of interspaced conducting nonmagnetic split ring resonators and continuous wires, that exhibits a frequency region in the microwave regime with
8,057 citations
TL;DR: In this article, an effective description for a metalodielectric photonic bandgap (PBG) material was developed for a semi-infinite and slab observables.
Abstract: An effective description is developed for a metalodielectric photonic bandgap (PBG) material far beyond the quasi-static limit of traditional effective-medium theories. An analytic approach, recently presented by the authors, is further advanced to provide the complete effective permittivity and permeability functions. Reflection and transmission coefficients are presented for both TM and TE oblique plane-wave incidence, based on the determination of the equivalent impedance for each lattice plane in the crystal and the transfer-matrix method for reconstructing the effect of successive lattice planes. An analysis of the semi-infinite and slab observables yields the anisotropic effective refractive index, effective permittivity, and effective permeability, thus completing the macroscopic description of the interaction of electromagnetic waves with the medium. Among the novel aspects of the analysis is the equivalence of our PBG system with a physically dispersive system at ultraviolet frequencies and the derivation and explanation of the development of high dispersive magnetization (permeability) for these media, independently of the microscopic magnetic properties of the metallic implants.
44 citations