Electrical Response of Systropic Sphere

Rimpiläinen, Tommi; Wallén, Henrik; Kettunen, Henrik; Sihvola, Ari

doi:10.1109/tap.2012.2207677

Cited by 11 publications

(13 citation statements)

References 14 publications

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“…[19][20][21][22][23][24] Such spheres have also been referred to using the term radially uniaxial. 25,26 Moreover, the general case, where all three components of ε are allowed to be different has been investigated in Ref. 25, where the sphere is called systropic.…”

Section: Introductionmentioning

confidence: 99%

Cloaking and magnifying using radial anisotropy

Kettunen

Wallén

Sihvola

2013

Journal of Applied Physics

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This paper studies the electrostatic responses of a polarly radially anisotropic cylinder and a spherically radially anisotropic sphere. For both geometries, the permittivity components differ from each other in the radial and tangential directions. We show that choosing the ratio between these components in a certain way, these rather simple structures can be used in cloaking dielectric inclusions with arbitrary permittivity and shape in the quasi-static limit. For an ideal cloak, the contrast between the permittivity components has to tend to infinity. However, only positive permittivity values are required and a notable cloaking effect can already be observed with relatively moderate permittivity contrasts. Furthermore, we show that the polarly anisotropic cylindrical shell has a complementary capability of magnifying the response of an inner cylinder.

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Section: Introductionmentioning

confidence: 99%

Cloaking and magnifying using radial anisotropy

Kettunen

Wallén

Sihvola

2013

Journal of Applied Physics

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“…The vanishing polarizability a k at the intersection of the curve with x-axis implies that the object becomes invisible to an observer of static fields when the excitation is uniform. Because the coefficients of the perturbation field in (14) and (16) depend linearly on the polarizability a, we conclude that a vanishing polarizability implies a vanishing perturbation field. Thus if the perturbation vanishes in the far-region of the inclusion, it must also vanish in the proximity of the inclusion.…”

Section: Cloaks and Concentratorsmentioning

confidence: 79%

“…When we let the axis ratio r approach 1, the parameter g 0 approaches positive infinity in the polarizability equations (14) and (16). In that limit, sinhðlg 0 Þ !…”

Section: Ra Circlementioning

confidence: 99%

“…The polarizability formulas (14) and (16), that we developed in Sec. III B, allow us to study the interplay of material and geometry in creating the electric response of the inclusion.…”

Section: Effects Of Radial Anisotropymentioning

confidence: 99%

“…1). While the homogeneous elliptic cylinder has been studied for both dynamic and static fields 5 and while the concept of radial anisotropy has been considered for circular cylinders 8,9 and spheres 10-15 before, even in a generalized sense, 16,17 the present study examines electrostatic scattering with a combination of material and geometric properties unprecedented, as far as the authors know, in the electromagnetic literature.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Polarizability of radially anisotropic elliptic inclusion

Rimpiläinen

Wallén

Sihvola

2016

Journal of Applied Physics

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This article discusses a two-dimensional electrostatic scattering problem where an elliptic inclusion is suspended in a homogeneous background and impinged by an electric field which is uniform and static. The novelty of the discussion stems from the inclusion's material parameters. The material of the inclusion is assumed to be axially anisotropic, so that the axis of anisotropy aligns itself with the radial unit vector of the elliptic coordinate system. Similar varieties of anisotropy have been formerly referred to as radial anisotropy, and the same term is employed herein. The radially anisotropic elliptic inclusions are studied with an analytic method. The validation is likewise analytic. The validation method compares the new results with the results for radially anisotropic circles and homogeneous two-dimensional needles. The elliptic inclusion is found to facilitate both cloaking and field concentration. V C 2016 AIP Publishing LLC. [http://dx.

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Anomalous absorption, plasmonic resonances, and invisibility of radially anisotropic spheres

2015

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This article analyzes the response of a sphere with radially anisotropic permittivity dyadic (RA sphere), in both the electrostatic and full electrodynamic settings. Depending on the values and signs of the permittivity components, the quasistatic polarizability of the RA sphere exhibits several very different interesting properties, including invisibility, field concentration, resonant singularities, and emergent losses. Special attention is given to the anomalous losses that appear in the case of certain hyperbolic anisotropy values. We show that their validity can be justified in a limiting sense by puncturing the sphere at the origin and adding a small imaginary part into the permittivity components. A hyperbolic RA sphere with very small intrinsic losses can thus have significant effective losses making it an effective absorber. With different choices of permittivities, the RA sphere could also perform as a cloak or a sensor. The Mie scattering results by an RA sphere are used to justify the quasistatic calculations. It is shown that in the small parameter limit the absorption efficiency of an RA sphere is nonzero for certain lossless hyperbolic anisotropies. The absorption and scattering efficiencies agree with the quasistatic calculations fairly well for spheres with size parameters up to 1/3.

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Electrical Response of Systropic Sphere

Cited by 11 publications

References 14 publications

Cloaking and magnifying using radial anisotropy

Cloaking and magnifying using radial anisotropy

Polarizability of radially anisotropic elliptic inclusion

Anomalous absorption, plasmonic resonances, and invisibility of radially anisotropic spheres

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