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- Freni, A., et al.
(författare)
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The European school of antennas within the ACE network
- 2005
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Ingår i: 35th European Microwave Conference 2005. - 2960055128 - 9782960055122 ; , s. 793-796
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Konferensbidrag (refereegranskat)abstract
- The Antenna Center of Excellence (ACE) Is a Network of Excellence funded by the EC 6th Framework Program. This paper describes the activities on Training and Education within the network and In particular the organization of a European School of Antennas with short courses on different antenna related topics taught be recognized experts In the respective fields.
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- Kehn, M. Ng Mou, 1976, et al.
(författare)
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Analysis of dispersion in dipole-FSS loaded hard rectangular waveguide
- 2006
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 54:8, s. 2275-2282
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the properties of the dipole frequency selective surfaces-loaded rectangular waveguide. The analysis is carried out by using the method of moments together with an algorithm that solves for a multilayer structure in the spectral domain. The eigenmodes are determined by searching for resonant solutions. Dispersion diagrams obtained from this approach are compared with those generated by commercial software simulations. Experimental validation is also performed. © 2006 IEEE.
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- Maci, S., et al.
(författare)
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Hard and Soft Gangbuster Surfaces
- 2004
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Ingår i: URSI International Symposium on Electromagnetic Theory, Pisa, Italy, May 2004.
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Konferensbidrag (refereegranskat)
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| 7. |
- Maci, S., et al.
(författare)
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The European School of Antennas : The new model of distributed PhD school of the Antenna Center of Excellence
- 2005
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Ingår i: IEEE Antennas & Propagation Magazine. - 1045-9243 .- 1558-4143. ; 47:4, s. 120-125
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Tidskriftsartikel (refereegranskat)abstract
- The European School of Antennas is a new model of a geographically distributed PhD school, which aims to improve the advanced antenna training and research in Europe. The school is organized in the framework of the Antenna Center of Excellence (ACE), a "Network of Excellence" financed by the sixth framework program of the European Union. The school is constituted as a highly qualified integrated set of advanced courses at the PhD level, distributed in the most accredited European research centers on antennas. The general objectives of the school are: i) strengthening the European excellence on antennas; ii) completing the individual PhD curricula of students in electrical and information engineering by offering interaction with the best trainers in Europe; iii) increasing the link between European universities and industries in antenna research and development; and iv) facilitating the interchange of ideas among early-stage researchers and teachers, thus increasing the future mobility and synergy. The school is furnished with centralized Web support, and this is coordinated so that the courses have the same format and apply common basic rules for exams and credits.
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- Martini, E., et al.
(författare)
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Degrees of freedom of the field and maximum directivity
- 2016
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Ingår i: 2016 URSI International Symposium on Electromagnetic Theory, EMTS 2016. - 9781509025039 ; , s. 775-776
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Konferensbidrag (refereegranskat)abstract
- This contribution discusses the relationship between the number of degrees of freedom (DoF) and the maximum directivity for an arbitrary set of sources enclosed by a given spherical surface. In particular, it is shown that the number of DoF is equal to twice the maximum directivity. This provides a directivity limitation for arbitrarily sized antennas, thus, extending the validity of the known formulas for electrically large and electrically small antennas.
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- McCall, Martin, et al.
(författare)
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Roadmap on transformation optics
- 2018
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Ingår i: Journal of Optics. - : IOP Publishing. - 2040-8978 .- 2040-8986. ; 20:6
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Forskningsöversikt (refereegranskat)abstract
- Transformation optics asks, using Maxwell's equations, what kind of electromagnetic medium recreates some smooth deformation of space? The guiding principle is Einstein's principle of covariance: that any physical theory must take the same form in any coordinate system. This requirement fixes very precisely the required electromagnetic medium. The impact of this insight cannot be overestimated. Many practitioners were used to thinking that only a few analytic solutions to Maxwell's equations existed, such as the monochromatic plane wave in a homogeneous, isotropic medium. At a stroke, transformation optics increases that landscape from 'few' to 'infinity', and to each of the infinitude of analytic solutions dreamt up by the researcher, there corresponds an electromagnetic medium capable of reproducing that solution precisely. The most striking example is the electromagnetic cloak, thought to be an unreachable dream of science fiction writers, but realised in the laboratory a few months after the papers proposing the possibility were published. But the practical challenges are considerable, requiring meta-media that are at once electrically and magnetically inhomogeneous and anisotropic. How far have we come since the first demonstrations over a decade ago? And what does the future hold? If the wizardry of perfect macroscopic optical invisibility still eludes us in practice, then what compromises still enable us to create interesting, useful, devices? While three-dimensional (3D) cloaking remains a significant technical challenge, much progress has been made in two dimensions. Carpet cloaking, wherein an object is hidden under a surface that appears optically flat, relaxes the constraints of extreme electromagnetic parameters. Surface wave cloaking guides sub-wavelength surface waves, making uneven surfaces appear flat. Two dimensions is also the setting in which conformal and complex coordinate transformations are realisable, and the possibilities in this restricted domain do not appear to have been exhausted yet. Beyond cloaking, the enhanced electromagnetic landscape provided by transformation optics has shown how fully analytic solutions can be found to a number of physical scenarios such as plasmonic systems used in electron energy loss spectroscopy and cathodoluminescence. Are there further fields to be enriched? A new twist to transformation optics was the extension to the spacetime domain. By applying transformations to spacetime, rather than just space, it was shown that events rather than objects could be hidden from view; transformation optics had provided a means of effectively redacting events from history. The hype quickly settled into serious nonlinear optical experiments that demonstrated the soundness of the idea, and it is now possible to consider the practical implications, particularly in optical signal processing, of having an 'interrupt-without-interrupt' facility that the so-called temporal cloak provides. Inevitable issues of dispersion in actual systems have only begun to be addressed. Now that time is included in the programme of transformation optics, it is natural to ask what role ideas from general relativity can play in shaping the future of transformation optics. Indeed, one of the earliest papers on transformation optics was provocatively titled 'General Relativity in Electrical Engineering'. The answer that curvature does not enter directly into transformation optics merely encourages us to speculate on the role of transformation optics in defining laboratory analogues. Quite why Maxwell's theory defines a 'perfect' transformation theory, while other areas of physics such as acoustics are not apparently quite so amenable, is a deep question whose precise, mathematical answer will help inform us of the extent to which similar ideas can be extended to other fields. The contributors to this Roadmap, who are all renowned practitioners or inventors of transformation optics, will give their perspectives into the field's status and future development.
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| 10. |
- Polemi, A., et al.
(författare)
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Dispersion Characteristics of a Metamaterial-Based Parallel-Plate Ridge Gap Waveguide Realized by Bed of Nails
- 2011
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Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 59:3, s. 904-913
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Tidskriftsartikel (refereegranskat)abstract
- The newly introduced parallel-plate ridge gap waveguide consists of a metal ridge in a metamaterial surface, covered by a metallic plate at a small height above it. The gap waveguide is simple to manufacture, especially at millimeter and sub-millimeter wave frequencies. The metamaterial surface is designed to provide a frequency band where normal global parallel-plate modes are in cutoff, thereby allowing a confined gap wave to propagate along the ridge. This paper presents an approximate analytical solution for this confined quasi-TEM dominant mode of the ridge gap waveguide, when the metamaterial surface is an artificial magnetic conductor in the form of a bed of nails. The modal solution is found by dividing the field problem in three regions, the central region above the ridge and the two surrounding side regions above the nails. The fields within the side regions are expressed in terms of two evanescent TE and TM modes obtained by treating the bed of nails as an isotropic impedance surface, and the field in the central ridge region is expanded as a fundamental TEM parallel-plate mode with unknown longitudinal propagation constant. The field solutions are linked together by equalizing longitudinal propagation constants and imposing point-continuity of fields across the region interfaces, resulting in a transcendental dispersion equation. This is solved and presented in a dispersion diagram, showing good agreement with a numerical solution using a general electromagnetic solver. Both the lower and upper cutoff frequencies of the normal global parallel-plate modes are predicted, as well as the quasi-TEM nature of the gap mode between these frequencies, and the evanescent fields in the two side regions decay very rapidly away from the ridge.
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