| 241. |
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| 242. |
- Sohl, Christian, et al.
(författare)
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Bounds on metamaterials in scattering and antenna problems
- 2007
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Ingår i: ; , s. 1-4
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Konferensbidrag (refereegranskat)abstract
- This paper reports on physical limitations on metamaterials in scattering and antenna problems. A dispersion relation for the extinction cross section is derived from the holomorphic properties of the forward scattering dyadic. The result states that for a given volume, there is only a limited amount of scattering and absorption available in the entire frequency range. The dispersion relation is verified numerically for the perfectly conducting circular disk, and theoretical bounds are illustrated for a plasmonic stratified sphere.
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| 243. |
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| 244. |
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| 245. |
- Sohl, Christian, et al.
(författare)
-
Physical limitations on antennas: isoperimetric inequalities and the effect of metamaterials
- 2007
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Ingår i: [Host publication title missing]. - 9789536037506 ; , s. 75-79
-
Konferensbidrag (refereegranskat)abstract
- In this paper, physical limitations on antennas are presented based on the holomorphic properties of the forward scattering dyadic. As a direct consequence of causality and energy conservation, a forward dispersion relation for the extinction cross section is established, and isoperimetric inequalities for the partial realized gain and partial directivity are derived for antennas of arbitrary shape. Closed-form expressions for the prolate and oblate spheroids are compared with Chu's classical result for the sphere, and the effect of invoking metamaterials in the antenna design is discussed. The theory is illustrated by numerical simulations of a monopole antenna with a finite ground plane.
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| 246. |
- Sohl, Christian, et al.
(författare)
-
Physical limitations on broadband scattering
- 2007
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Ingår i: ; , s. 1-3
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Konferensbidrag (refereegranskat)abstract
- In this paper, physical limitations on broadband scattering are presented for heterogeneous anisotropic scatterers of arbitrary shape. A measure of broadband scattering in terms of the extinction cross section is derived based on the holomorphic properties of the forward scattering dyadic. An isoperimetric bound for isotropic material parameters is presented and ellipsoidal scatterers are discussed. Finally, the theoretical results are illustrated numerically by a generic scatterer.
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| 247. |
- Sohl, Christian, et al.
(författare)
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Physical limitations on broadband scattering by heterogeneous obstacles
- 2007
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Ingår i: Journal of Physics A: Mathematical and Theoretical. - : IOP Publishing. - 1751-8113 .- 1751-8121. ; 40:36, s. 11165-11182
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, new physical limitations on the extinction cross section and broadband scattering are investigated. A measure of broadband scattering in terms of the integrated extinction is derived for a large class of scatterers based on the holomorphic properties of the forward scattering dyadic. Closed-form expressions of the integrated extinction are given for the homogeneous ellipsoids, and theoretical bounds are discussed for arbitrary heterogeneous scatterers. Finally, the theoretical results are illustrated by numerical computations for a series of generic scatterers
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| 248. |
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| 249. |
- Sohl, Christian, et al.
(författare)
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Physical limitations on G and B for antennas
- 2007
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Ingår i: ; , s. 1-3
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Konferensbidrag (refereegranskat)abstract
- In this paper, physical limitations on the partial gain G and relative bandwidth B are derived for antennas of arbitrary shape based on holomorphic properties of the forward scattering dyadic. The limitation on the performance of G and B is shown to be bounded from above by the long wavelength response of the antenna in terms of the electric and magnetic polarizability dyadics. The special case of ellipsoidal geometries are discussed.
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| 250. |
- Sohl, Christian, et al.
(författare)
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Physical limitations on metamaterials: restrictions on scattering and absorption over a frequency interval
- 2007
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Ingår i: Journal of Physics D: Applied Physics. - : IOP Publishing. - 1361-6463 .- 0022-3727. ; 40:22, s. 7146-7151
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Tidskriftsartikel (refereegranskat)abstract
- A limitation on the extinction cross section, valid for all scatterers satisfying some basic physical assumptions, is investigated. The physical limitation is obtained from the holomorphic properties of the forward scattering dyadic. The analysis focuses on the consequences for materials with negative permittivity and permeability, i.e. metamaterials. From a broadband point of view, the limitations imply that there is no fundamental difference between metamaterials and ordinary materials with respect to scattering and absorption. The analysis is illustrated by three numerical examples of metamaterials modelled by temporal dispersion.
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