| 1. |
- Horsley, S. A. R., et al.
(författare)
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Removing singular refractive indices with sculpted surfaces
- 2014
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 4, s. 4876-
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Tidskriftsartikel (refereegranskat)abstract
- The advent of Transformation Optics established the link between geometry and material properties, and has resulted in a degree of control over electromagnetic fields that was previously impossible. For waves confined to a surface it is known that there is a simpler, but related, geometrical equivalence between the surface shape and the refractive index, and here we demonstrate that conventional devices possessing a singularity-that is, the requirement of an infinite refractive index-can be realised for waves confined to an appropriately sculpted surface. In particular, we redesign three singular omnidirectional devices: the Eaton lens, the generalized Maxwell Fish-Eye, and the invisible sphere. Our designs perfectly reproduce the behaviour of these singular devices, and can be achieved with simple isotropic media of low refractive index contrast.
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| 2. |
- Mitchell-Thomas, R. C., et al.
(författare)
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Lenses on curved surfaces
- 2014
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 39:12, s. 3551-3554
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Tidskriftsartikel (refereegranskat)abstract
- This Letter presents a theory that allows graded index lenses to be mapped onto arbitrary rotationally symmetric curved surfaces. Examples of the Luneburg and Maxwell fish-eye lens are given, for numerous surfaces, always resulting in isotropic permittivity requirements. The performance of these lenses is initially illustrated with full-wave simulations utilizing a waveguide structure. A transformation of the refractive index profiles is then performed to design surface-wave lenses, where the dielectric layer is not only isotropic but also homogenous, demonstrating the applicability and ease of fabrication.
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| 3. |
- Mitchell-Thomas, R. C., et al.
(författare)
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The anti-fish eye cloak for surface wave antennas
- 2014
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Ingår i: 8th European Conference on Antennas and Propagation, EuCAP 2014. - 9788890701849 ; , s. 267-268
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Konferensbidrag (refereegranskat)abstract
- In this paper a new lens, named the anti-fish eye lens, is proposed and its relation to the Maxwell fish eye lens is described. This novel lens is then applied to cloak an object positioned underneath it, to electromagnetic waves that are confined to the surface. The performance of the lens in reforming the cylindrical wave fronts is illustrated with numerical simulations. This lens has direct applications for surface wave antennas that are conformal to curved structures to remove the influence of the curvature, the consequence of which would detrimentally affect the directivity because of the distortion of the wavefronts. Therefore, using this technique, the performance of surface wave antennas on curved surfaces can be equivalent to those on flat surfaces.
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| 4. |
- Quevedo-Teruel, Oscar, et al.
(författare)
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Conformal surface lenses from a bed of nails
- 2014
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Ingår i: 8th European Conference on Antennas and Propagation, EuCAP 2014. - 9788890701849 ; , s. 269-270
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Konferensbidrag (refereegranskat)abstract
- This paper presents a validation of a fast method for calculating the propagation constant of a periodic bed of nails structure. These results are compared to full wave simulation results, showing good agreement. This method is then employed to design a Luneburg lens which is conformal to the surface of a sphere. The index distribution required to create this conformal lens was calculated using an optical path technique. This work has applications for the design of communication systems for vehicles and airborne platforms.
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