| 41. |
- Gustafsson, Mats, et al.
(författare)
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Constraints on the temporal dispersion of metamaterials
- 2010
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Ingår i: Proceedings of the Fourth European Conference on Antennas and Propagation. - 9781424464319 - 9788476534724 ; , s. 1-3
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Konferensbidrag (refereegranskat)abstract
- The frequency dependence of the permittivity, permeability, and index of refraction restrict metamaterial applications such as cloaking and perfect lenses. Here, the principles of causality and passivity together with identities for Herglotz functions are used to construct various sum rules. The sum rules relate the frequency dependence of the material parameters with their high- and low-frequency values. The corresponding physical bounds determine minimum variations of the material parameters over a frequency interval.
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| 42. |
- Gustafsson, Mats, et al.
(författare)
-
Constraints on the temporal dispersion of passive metamaterials
- 2011
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Ingår i: 2011 XXXth URSI General Assembly and Scientific Symposium. - 9781424451173 - 9781424460519
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Konferensbidrag (refereegranskat)abstract
- Metamaterial applications such as cloaking, perfect lenses, and artificial permeability are restricted by the frequency dependence of the permittivity, permeability, and index of refraction. Here, causality and passivity together with integral identities for Herglotz functions are used to construct sum rules. The sum rules relate the frequency dependence of the material parameters with their high- and low-frequency values. The corresponding physical bounds determine the minimum variations of the material parameters over a frequency interval. The results are illustrated with a numerical example for artificial permeability.
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| 43. |
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| 44. |
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| 45. |
- Gustafsson, Mats, et al.
(författare)
-
On the extraordinary transmission through sub-wavelength apertures in perfectly conducting sheets
- 2011
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Ingår i: 2011 International Conference on Electromagnetics in Advanced Applications : Proceedings of a meeting held 12-16 September 2011, Torino, Italy. - Proceedings of a meeting held 12-16 September 2011, Torino, Italy.. - 9781612849775
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Konferensbidrag (refereegranskat)abstract
- Extraordinary transmission of electromagnetic power through sub-wavelength apertures is usually observed in a narrow bandwidth range and the transmission outside this range is low. In this paper, it is shown that the transmission through periodic apertures in an otherwise perfectly electric conducting sheet satisfies a sum rule that relates wavelength regions with transmission above a threshold with the polarizability of the complementary structure. The theoretical results are illustrated with a numerical example for split ring apertures.
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| 46. |
- Gustafsson, Mats, et al.
(författare)
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On the radiation resistance for small capacitive dipole antennas
- 2011
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Ingår i: ; , s. 3853-3854
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Konferensbidrag (refereegranskat)abstract
- A relation between the radiation resistance and the quasi-static polarizability, input capacitance, and input inductance for small electric dipole antennas is investigated. The relation follows from the forward scattering sum rule and sum rules for the input impedance together with resonance models for the partial realized gain and the reflection coefficient.
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| 47. |
- Gustafsson, Mats, et al.
(författare)
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Optical theorem and forward scattering sum rule for periodic structures
- 2012
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X. ; 60:8, s. 3818-3826
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Tidskriftsartikel (refereegranskat)abstract
- Based on energy conservation, an optical theorem is constructed for a slab having an arbitrary periodic microstructure in a plane. A sum rule for low pass structures is derived using analytic properties of Herglotz functions based on causality and passivity. The sum rule relates the total cross section to the static polarizability per unit cell, and quantifies the interaction between the slab and electromagnetic fields possible over all wavelengths. The results are illustrated with several numerical and experimental examples.
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| 48. |
- Gustafsson, Mats, et al.
(författare)
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Optical theorem and forward scattering sum rule for periodic structures
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Based on energy conservation, an optical theorem is constructed for a slab having an arbitrary periodic microstructure in a plane. A sum rule for low pass structures is derived using analytic properties of Herglotz functions based on causality and passivity. The sum rule relates the extinction cross section to the static polarizability per unit cell, and quantifies the interaction between the slab and electromagnetic fields possible over all wavelengths. The results are illustrated with several numerical and experimental examples.
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| 49. |
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| 50. |
- Gustafsson, Mats, et al.
(författare)
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Physical bounds and sum rules for high-impedance surfaces
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- High-impedance surfaces are artificial surfaces synthesized from periodic structures. The high impedance is useful as it does not short circuit electric currents and reflects electric fields without phase shift. Here, a sum rule is presented that relates frequency intervals having high impedance with the thickness of the structure. The sum rule is used to derive physical bounds on the bandwidth for high-impedance surfaces. Numerical examples are used to illustrate the result, and show that the physical bounds are tight.
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