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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01 Dec 2019
TL;DR: In this paper, a reflectarray with spiral-shaped resonant elements was used as a carpet cloak for dual polarization cloaking in cloaking devices, which is suitable for cloaking with very thin and simple structure.
Abstract: Reflecting elements for cloaking technology has attracted recent attention. A reflectarray having very thin and simple structure is suitable to cloaking devices. We propose here to use a reflectarray with spiral-shaped resonant elements as a carpet cloak for dual polarization.
01 Jan 2013
TL;DR: In this article, a split-ring resonator (SRR) was used to provide magnetic responses at any desired frequency, and the concept of metamaterial was greatly expanded to beyond negative-index materials.
Abstract: In 1968, Veselago proposed that a medium with simultaneously negative permittivity and permeability possesses a negative refractive index, and exhibits many unusual EM properties [1]. This proposal did not attract immediate attention, since it is well accepted that a natural material shows no magnetism at high frequencies [2]. A breakthrough appeared in 1999, when Pendry showed that a split-ring resonator (SRR) could provide magnetic responses at any desired frequency [3]. Metamaterials with negative refractive index were then successfully fabricated by combining SRRs and electric wires [4], and later the concept of metamaterial was greatly expanded to beyond negative-index materials. Many unusual EM phenomena were subsequently demonstrated based on metamaterials, such as negative refraction [4, 5, 6, 7, 8, 9, 10], super focusing [11, 12, 13, 14], and subwavelength resonant cavities [15, 16, 17].
20 Jun 2004
TL;DR: In this article, the authors derived general formulas/algorithms for computing effective electric permittivity and magnetic permeability for polarizable media from first-principles classical E and M. They applied them to filamentary, conducting structures that are candidates for making double-negative metamaterials.
Abstract: There is considerable interest in the design of metamaterials for specific unusual electromagnetic properties. We want materials with particular values of epsilon and mu that are less than zero. We desired a calculation procedure that could take a geometric structure and evaluate the effective material parameters, both for design validation and in a search for new shapes. There have been other descriptions of similar efforts in the literature; our method is an improvement over the existing methods by reducing the errors due to phase variation across a structure while not requiring a solver that calculates the charge and current directly. We derive general formulas/algorithms for computing effective electric permittivity /spl epsi/(/spl omega/) and magnetic permeability /spl mu/(/spl omega/) for polarizable media from first-principles classical E and M. We apply them to filamentary, conducting structures that are candidates for making double-negative metamaterials. Specifically we show we can analyze specific structures and design a material where /spl epsi/(/spl omega/) and /spl mu/(/spl omega/) are simultaneously negative. We use the split-ring resonators and capacitively-end-loaded linear electric dipoles as examples and show that they form Lorentz materials.
01 Jan 2008
TL;DR: In this paper, it is shown that it is impossible to build metamaterials using any number of passive unit cells, and a solid proof over violation of energy conservation in the intersection plane between a normal material and a left-hand material is presented which requires us to believe and accept generation of energy at this plane.
Abstract: In all attempts to analyze and realize Left-Handed materials, so far, most researchers have used the same idea of extracting only some or certain behaviors of Metamaterials from a set of unit cells gathered together in a designed order Nevertheless meeting all criteria in order to consider a media as real double-negative material has never come trueStarting with criticizing and arguing the validity of calling any set of unit cells as a medium of propagation, the work at hand will go further demonstrating analogies between a medium which could be assigned permittivity or permeability factors and the medium consisting a set of unit cellsAfter presenting the critical analysis on previous studies in the field, here it is shown that it is impossible to build Metamaterials using any number of passive unit cells A deep insight into the concept of phase and group velocities as well as Poynting’s vector will reveal weakness of the public perception of their relation with each other Unlike the past and current trend in analyzing these two velocities in meta-materials, they will be proven to possess the same directionMoreover, in this work, a solid proof over violation of energy conservation in the intersection plane between a normal material and a Left Handed material is presented which requires us to believe and accept generation of energy at this plane This view will consequently leave meaningless all attempts to build meta-materials by passive elementsIn present work a method is proposed at which a material with positive permittivity and permeability can behave like and yield all characteristics of Metamaterials only if the foregoing parameters, while remaining positive, can vary and be governed by the magnitude of the electromagnetic field Independence of this method from frequency broadens the range of its application and also the interest it may attract
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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