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Proceedings ArticleDOI

Effective electromagnetic properties of structured chiral metamaterials

TL;DR: In this article, a methodology to evaluate the effective parameters of a three-dimensional lattice of chiral inclusions is presented, where the homogenization is based upon mathematical arguments.
Abstract: A novel methodology to evaluate the effective parameters of a three-dimensional lattice of chiral inclusions is presented. The homogenization is based upon mathematical arguments. The finite element technique is used to compute the constitutive parameters.
Citations
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Journal ArticleDOI
TL;DR: In this article, the quasi-static homogenized constitutive parameters of biperiodic chiral artificial material are computed by using the finite element method and the results are compared to existing results in literature.
Abstract: This paper presents a new and efficient method to compute the quasi-static homogenized constitutive parameters of biperiodic chiral artificial material. In this method, the studied domain is reduced to an elementary cell with pseudo-periodic conditions on the lateral sides and the local electromagnetic properties are computed by using the finite-element method. This chiral media is decomposed into two equivalent isotropic media and each one is treated separately. Indeed, the homogenized constitutive parameters of each isotropic media are expressed as a function of the macroscopic electromagnetic properties which are obtained by averaging the local electromagnetic properties. The homogenized constitutive parameters of the initial chiral material are expressed using the two equivalent isotropic materials. The validation of the numerical results is presented in the case of the lattices with 3-D inclusions. In addition, the obtained results are compared to existing results in literature. Finally, the incidence wave angle impact on the homogenized parameters is studied.

15 citations

Journal ArticleDOI
TL;DR: In this article, a method for homogenizing the bi-periodic materials with bi-isotropic components phases is presented, which is a numerical method based on the finite element method to compute the local electromagnetic properties.
Abstract: In this paper, we present a new method for homogenizing the bi-periodic materials with bi-isotropic components phases. The presented method is a numerical method based on the finite element method to compute the local electromagnetic properties. The homogenized constitutive parameters are expressed as a function of the macroscopic electromagnetic properties which are obtained from the local properties. The obtained results are compared to Unfolding Finite Element Method and Maxwell–Garnett formulas.

7 citations

Journal ArticleDOI
TL;DR: The partial element equivalent circuit (PEEC) method is applied to a frequency-sweep study for investigating the resonant modes of planar spiral resonators and an low-rank approximation algorithm, based on hierarchical matrices, is coupled to the method in order to reduce the computational effort.
Abstract: The partial element equivalent circuit (PEEC) method is applied to a frequency-sweep study for investigating the resonant modes of planar spiral resonators. A low-rank approximation algorithm, based on hierarchical matrices, is coupled to the method in order to reduce the computational effort due to the use of dense matrices. The partitioning of the matrices is carefully addressed in order to allow an efficient hierarchical off-diagonal low-rank structure of the system matrix.

7 citations

Journal ArticleDOI
TL;DR: In this article, the effective constitutive parameters of the initial structure are evaluated as a function of the two equivalent media's parameters, in order to validate the proposed analytical expressions, the numerical results are compared to the homogenization's multiscale method.
Abstract: In this paper, we present new expressions of the effective constitutive parameters of bi-isotropic multilayered structure having an arbitrary number of layers and different thicknesses. The present method uses the decomposition scheme, and the commutativity between the homogenization process and the decomposition scheme is supposed. The effective constitutive parameters of the initial structure are evaluated as a function of the two equivalent media's parameters. In order to validate the proposed analytical expressions, the numerical results are compared to the homogenization's multiscale method.

5 citations

Proceedings ArticleDOI
09 May 2016
TL;DR: A new approach to impose periodic boundary conditions on arbitrary mesh based on writing each unknown of the first side as function of the unknowns of the opposite side of the matrix system obtained by finite element discretization.
Abstract: This paper presents a new approach to impose periodic boundary conditions on arbitrary mesh. This method is based on two steps; the first one consists in writing each unknown of the first side as function of the unknowns of the opposite side. The second step is to introduce the periodicity relations in the matrix system obtained by finite element discretization. The proposed method has been applied in the context of homogenization problem.

3 citations


Cites background from "Effective electromagnetic propertie..."

  • ...The electromagnetic properties can be computed directly or by homogenization procedure if the period of the studied structure is small compared to incident wavelength [1-4]....

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References
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Journal ArticleDOI
TL;DR: Cioranescu et al. as discussed by the authors proposed a novel approach to periodic homogenization based on an unfolding method, which leads to a fixed domain problem without singularly oscillating coefficients.

456 citations

Journal ArticleDOI
TL;DR: In this paper, a uniform separated-grain structure with regular hcp Co particles embedded in Al2O3 was found for Co contents (fCos) up to ∼30 vol
Abstract: Co‐Al2O3 composite films were produced by electron‐beam coevaporation in a system with elaborate process control. The deposits were analyzed by transmission electron microscopy, electron diffraction, Auger electron spectroscopy, secondary ion mass spectroscopy, Rutherford backscattering, field ion microscopy, mechanical stylus measurements, and electrical dc and ac measurements. A uniform separated‐grain structure with regular hcp Co particles embedded in Al2O3 was found for Co contents (fCos’) up to ∼30 vol %. The complex dielectric permeability e was evaluated in the 0.3≲λ≲40‐μm wavelength range for samples with 0.11≲ fCo ≲0.60 by carefully selected combinations of spectrophotometric transmittance and reflectance data. Numerical accuracy and internal consistency were investigated. Effective medium theories for e were derived by applying classical scattering theory to spherical random unit cells defined so as to properly represent a number of typical microgeometries. The formulations due to Maxwell Garnett, Bruggeman, and others were thus rederived in a unified way. Large‐size limits of validity and extensions to nonspherical particles were treated. It was found that the Maxwell Garnett theory could reproduce the experimental e’s in detail at low fCo provided that some Co was taken to be dispersed in the insulating matrix. At larger fCo’s we found discrepancies which are likely to be due mainly to dipole‐dipole coupling among adjacent particles. A comparison of the experimental e’s and the rigorous Bergman–Milton bounds, which hold irrespective of detailed microgeometry, gave several interesting results: the e’s varied monotonically along one of the bounds for isotropic materials as fCo was increased, at large fCo we found evidence for anisotropy, and at λ≊12.5 μm we noted certain cases of disagreement with even the most generous bounds. The empirical e’s were used to construct surfaces which combine a high solar absorptance as with a low hemispherical thermal emittance eH. From a computer optimization study we found that as =0.95 and eH =0.07 could be obtained with 0.07 μm of Co‐Al2O3 ( fCo≊0.6) antireflected with 0.07 μm of Al2O3 and laid on Ni. These results were verified by measurements on samples which approximate the ideal design.

370 citations

Journal ArticleDOI
Winston E. Kock1
01 Nov 1946
TL;DR: In this article, a new type of antenna is described which utilizes the optical properties of radio waves, which consists of a number of conducting plates of proper shape and spacing and is, in effect, a lens, the focusing action of which is due to the high phase velocity of a wave passing between the plates.
Abstract: A new type of antenna is described which utilizes the optical properties of radio waves. It consists of a number of conducting plates of proper shape and spacing and is, in effect, a lens, the focusing action of which is due to the high phase velocity of a wave passing between the plates. Its field of usefulness extends from the very short waves up to wavelengths of perhaps five meters or more. The paper discusses the properties of this antenna, methods of construction, and applications.

252 citations

Journal ArticleDOI
TL;DR: In this article, the behavior of the electromagnetic field of a medium presenting periodic microstructures made of bianisotropic material was studied and the limiting homogeneous constitutive law was rigorously justified both in the time domain and in the frequency domain.

64 citations