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, the authors investigated the transmitted behavior of a subwavelength grid slab to explore the underlying mechanism of wave propagation and found that there is a large tolerance of directive emission even with a tilted slab.
8 citations
TL;DR: In this paper, a coplanar waveguide-fed multiple-input multiple-output antenna array based on the left-handed wire loaded spiral resonators (SR) is presented.
Abstract: A compact coplanar waveguide-fed multiple-input multiple-output antenna array based on the left-handed wire loaded spiral resonators (SR) is presented. The proposed antenna consists of a 2 × 2 wire SR with two symmetrical microstrip feed lines, each line exciting a 1 × 2 wire SR. Left-handed metamaterial unit cells are placed on its reverse side and arranged in a 2 × 3 array. A reflection coefficient of less than −16 dB and mutual coupling of less than −28 dB are achieved at 5.15 GHz WLAN band.
8 citations
TL;DR: In this article, a formulation for deriving effective medium properties of infinitely periodic two-dimensional metamaterial lattice structures beyond the conventional static and quasi-static limits is presented, where the polarization currents associated with the supported Bloch modes are expressed via the electric dipole, magnetic dipole and electric quadrupole moments per unit length.
Abstract: We present a formulation for deriving effective medium properties of infinitely periodic two-dimensional metamaterial lattice structures beyond the conventional static and quasi-static limits. We utilize the multipole expansions, where the polarization currents associated with the supported Bloch modes are expressed via the electric dipole, magnetic dipole, and electric quadrupole moments per unit length. We then propose a method to calculate the Bloch modes based on the lattice geometry and individual unit element structure. The results revert to well-known formulas in the traditional quasistatic limit and are useful for the homogenization of nanorod-type metamaterials which are frequently used in optical applications.
7 citations
01 Aug 2013
TL;DR: A hybrid EM-optimization method using continuous-GA blended with MLP-ANN models is used for fast and accurate evaluation of cost function into continuous- GA simulations, in order to overcome the computational requirements associated with full wave numerical simulations for an optimization of the effective permittivity of the metamaterial.
Abstract: Metamaterials are a broad class of artificial materials that could be engineered to wield effective permittivity and permeability characteristics to system requirements. In this work, a hybrid EM-optimization method using continuous-GA blended with MLP-ANN models is used for fast and accurate evaluation of cost function into continuous-GA simulations, in order to overcome the computational requirements associated with full wave numerical simulations for an optimization of the effective permittivity of the metamaterial.
7 citations
TL;DR: In this article, Parabolic Split Ring Resonator (PSRR) based metamaterial with a wider refractive index is introduced for WiFi/WiMax/Wireless/ISM band applications and printing on Rogers RT-5880 lossy substrate with a copper-based metallic structure at 5.5-6.3 GHz within the microwave frequency region.
7 citations
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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