Papers by André de Lustrac
Metamaterials II, 2007
Dielectric substrates supporting planar periodic subwavelength metamaterial-based metallic arrays... more Dielectric substrates supporting planar periodic subwavelength metamaterial-based metallic arrays and presenting frequency dispersive phase characteristics are applied to ultra-compact high-gain and high-directivity planar antennas. In this paper, different models of metamaterial-based surfaces introducing a zero degree reflection phase shift to incident waves are firstly studied numerically using finite-element method analysis where the bandwidth and operation frequency are predicted. These surfaces are then applied in a resonant Fabry-Perot type cavity and a ray optics analysis is used to design different models of ultra-compact high-gain microstrip printed antennas. Firstly, a cavity antenna of thickness λ/60 based on the use of a microstrip patch antenna and two bidimensional metamaterial-based surfaces, the first one acting as a High Impedance Surface (HIS) and the second one acting as a Partially Reflecting Surface (PRS) is designed. This cavity is then optimized for easier fabrication process and loss reduction by the use of only one bidimensionnal composite metamaterial-based surface acting as a PRS. Secondly, another surface presenting a variable phase by the use of a non periodic metamaterial-based metallic strips array is designed for a passive low-profile steering beam antenna application. Finally, a switchable operation frequency cavity by the implementation of varicap diodes is designed and fabricated. All these cavity antennas operate on subwavelength modes, the smallest cavity thickness being of the order of λ/60.
This article deals with the modeling, practical implementation, and characterization of an azimut... more This article deals with the modeling, practical implementation, and characterization of an azimuthal directive antenna around 10 GHz. The design of the antenna is based on transformation optics concept by transforming the radiation of a plane source into an azimuthal radiation. This coordinate transformation procedure is achieved by modifying the electromagnetic properties of the space around the plane source. Metamaterials presenting electric and magnetic resonances are used to produce the effective material parameters necessary for the transformation. S11 parameter and direct far-field measurements are performed on a fabricated prototype to experimentally demonstrate the narrow beam profile and the beam deflection.
2014 International Workshop on Antenna Technology: Small Antennas, Novel EM Structures and Materials, and Applications (iWAT), 2014
The in-phase radiation from a conformal metasurface is numerically and experimentally reported. T... more The in-phase radiation from a conformal metasurface is numerically and experimentally reported. The LC-resonant metasurface is composed of a simultaneously capacitive and an inductive grid constituted by copper strips printed on both sides of a dielectric board. The metasurface is designed to fit a curved surface by modifying its local phase. The latter phase-compensated metasurface is used as a reflector in a conformal Fabry-Perot resonant cavity antenna. Far-field measurements performed on a fabricated prototype allow showing the good performances of such a phase-compensated metasurface in restoring in-phase emissions from the conformal surface and producing a directive emission in the desired direction.
2013 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2013
The use of transformation optics concept to change the physical size of radiating sources is inve... more The use of transformation optics concept to change the physical size of radiating sources is investigated. By choosing transformations that compress space, and then match it to the surrounding radiation environment, we are able to miniaturize the physical size of the embedded source. We show that a small aperture antenna can then behave as one with a large aperture. A study of the transformation of the space metric and the material parameter calculation is presented. Simulations are performed to validate the proposed approach at microwave frequencies. This study paves the way to interesting applications in telecommunications and aeronautical domain.
2013 7th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics, 2013
Transformation optics concept is used to change the physical size of radiating sources. By choosi... more Transformation optics concept is used to change the physical size of radiating sources. By choosing transformations that either compress or expand space, and then match it to the surrounding radiation environment, we are able to either increase or reduce the aperture size of the embedded source. We show that a small aperture antenna can then behave as one with a large aperture and vice-versa. A study of the two transformations of the space metric is presented. Simulations are performed to validate the proposed approach at microwave frequencies. This study paves the way to interesting applications in telecommunications and aeronautical domains.
2011 XXXth URSI General Assembly and Scientific Symposium, 2011
This paper deals with the modelling, practical implementation and characterization of an ultra-di... more This paper deals with the modelling, practical implementation and characterization of an ultra-directive antenna around 10 GHz. The design of the antenna is based on transformation optics concept by transforming a radiating cylindrical space into a rectangular one. Metamaterials presenting electric and magnetic resonances are used to achieve the transformation. Field intensity mappings and direct far field measurements are performed to experimentally demonstrate the narrow beam profile.
2012 6th European Conference on Antennas and Propagation (EUCAP), 2012
Using the idea of wave manipulation via coordinate transformation, we demonstrate the design of n... more Using the idea of wave manipulation via coordinate transformation, we demonstrate the design of novel antenna concepts. The manipulation is enabled by composite metamaterials that realize the space coordinate transformation. We present the design, realization and characterization of three types of antennas: a directive, a quasi-isotropic and a beam steerable one. Numerical simulations together with experimental measurements are performed in order to validate the concept. Near-field cartography and far-field pattern measurements performed on a fabricated prototype agree qualitatively with Finite Element Method (FEM) simulations. It is shown that a particular radiation can be transformed at ease into a desired one by modifying the electromagnetic properties of the space around it. This idea can find various applications in novel antenna design techniques for aeronautical and transport domains.
2011 XXXth URSI General Assembly and Scientific Symposium, 2011
This paper deals with the modeling and characterization of a broadband frequency agile metamateri... more This paper deals with the modeling and characterization of a broadband frequency agile metamaterial-based cavity antenna around 2 GHz. An electronically active metasurface is used as a Partially Reflecting Surface (PRS) and the cavity is excited by an array of four wideband L-strip fed printed microstrip patch antennas. A reconfigurable resonance frequency between 1.9 and 2.31 GHz is obtained and a directivity of 18 dBi is observed for a cavity thickness of λ/10 at 2 GHz.
Metamaterials III, 2008
Since the event of metamaterials, a considerable effort is being performed to fabricate them in t... more Since the event of metamaterials, a considerable effort is being performed to fabricate them in the infrared and optical regimes. However, apart from the experimental demonstration and observation of H. J. Lezec et al.[3] based on surface plasma polariton, direct visualisation of negative refraction based on metal-dielectric resonances have not been performed experimentally so far in the infrared or visible regime (photonic crystals with periodicity on the order of the wavelength are not considered here). Up to now, only simulations have given the needed phase information for the retrieval methods in optical experiments . In this paper, a metamaterial composed of SRR (Split Ring Resonators) and continuous wires is considered. We extract the phase information from the transmission and the reflection measurements through a diffraction grating made of the metamaterial to be characterized and silicon or gold. This retrieval leads to unambiguous effective parameters under conditions discussed in the paper. The good agreement between the calculated and the experimental results demonstrate that our method allows an exact determination of the effective parameters of a metamaterial at IR and visible wavelengths.
IEEE Antennas and Wireless Propagation Letters, 2014
Using transformation electromagnetics concept, we introduce an approach to virtually delocalize r... more Using transformation electromagnetics concept, we introduce an approach to virtually delocalize radiating sources and to transform their radiation pattern at the same time. We propose the design of an electromagnetic device that can virtually change the location of the emission point. By applying radial transformations that compress space, and then match it to the surrounding environment, we show how the emission of a radiating element placed in a core region can be delocalized in a second impedance-matched region, corresponding to a space folding. Moreover, the radiation pattern of the virtual source can be modified such that an omnidirectional radiation can be changed into a directive one. We describe the space coordinate transformation and the calculation of the material parameters. Full-wave simulations are performed at different frequencies to validate the proposed approach.
Transformation Electromagnetics and Metamaterials, 2013
ABSTRACT The use of transformation electromagnetics for microwave applications is presented. Impl... more ABSTRACT The use of transformation electromagnetics for microwave applications is presented. Implementation of non-standard devices such as microwave antennas and waveguide tapers proposed by the Institut d’Electronique Fondamentale at the University of Paris-Sud are reviewed. The operating principle and the respective coordinate transformation of each device is presented and numerical simulations are performed to verify the theoretical formulations. The method to obtain constitutive electromagnetic parameters mimicking the calculated transformed space is detailed and confirmed by full-wave simulations performed using discrete material parameter values and by measurements performed on fabricated metamaterial-based prototypes. The results show that transformation electromagnetics is very interesting for the design and realization of high-performance non-standard devices.
2013 7th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics, 2013
ABSTRACT We address the potential of a metamaterials in a guided wave configuration for applicati... more ABSTRACT We address the potential of a metamaterials in a guided wave configuration for applications in the near IR domain. We consider a hybrid type structure made of 2D metamaterial array over a high index slab waveguide, as for instance silicon our case. The experimental and modeling results show that effective index and loss level in such hybrid waveguides can be carefully controlled by the engineering of metamaterial resonances. The investigated approach may constitute a promising alternative to the bulk multi-layers metamaterial structures.
Applied Physics A, 2014
A planar microwave ultrathin broadband absorber is proposed. It is composed of metallic patterns ... more A planar microwave ultrathin broadband absorber is proposed. It is composed of metallic patterns arranged on a dielectric material which is backed by a copper plate. The patterns of different dimensions allow to judiciously design absorption peaks at specific frequencies of interest. These peaks are due to the mode resonances of the cavities formed by the metallic patches, the dielectric substrate and the copper plate. In order to widen the absorption bandwidth, patterns of different dimensions are used, together with the different modes of these cavities. Numerical and experimental results are presented to validate the proposed method at microwave frequencies. It is also shown that the use of a composite air dielectric substrate supporting the metallic patterns helps to increase the absorption level.
La transformation de coordonnées spatiales est un outil approprié pour la conception de structure... more La transformation de coordonnées spatiales est un outil approprié pour la conception de structures complexes électromagnétiques. Dans cet article, nous définissons trois transformations qui montrent la possibilité de concevoir un adaptateur entre deux guides d'ondes différents. Une étude paramétrique est présentée pour les trois transformations et nous proposons des valeurs réalisables de la permittivité et de la perméabilité qui peuvent être obtenues avec des métamatériaux existants. Les performances de ces structures sont démontrées par des simulations numériques basées sur la méthode des éléments finis.
Une surface à métamatériau à phase variable est proposée pour la conception d'une antenne à cavit... more Une surface à métamatériau à phase variable est proposée pour la conception d'une antenne à cavité Fabry-Pérot reconfigurable en fréquence. Cette métasurface est constituée de deux grilles de pistes métalliques, une inductive et une capacitive, disposées sur les deux faces d'un substrat diélectrique. Des diodes varicaps sont insérées dans la grille capacitive entre deux pistes adjacentes. Selon la tension de polarisation appliquée la phase de cette surface varie. Cette surface est ensuite utilisée comme une Surface Partiellement Réfléchissante (SPR) dans une antenne à cavité compacte (15 mm pour une fréquence centrale de 2,1
In this paper, we propose an easy way to manipulate the magnetic and electric resonances of cut w... more In this paper, we propose an easy way to manipulate the magnetic and electric resonances of cut wire pairs metamaterials to produce a negative index. We show that judiciously breaking the symmetry of the structure allows a tuning of both resonances leading to an overlapping between the negative permeability and negative permittivity regions. Numerical and experimental parametric studies of several cut wire pairs metamaterials are presented to validate our method at microwave frequencies.
The analysis and design of subwavelength metamaterial-based resonant cavity antennas are presente... more The analysis and design of subwavelength metamaterial-based resonant cavity antennas are presented. The antennas under investigation are formed by embedding a feeding source in a Fabry-Perot (FP) cavity composed of a Perfect Electrical Conductor (PEC) surface and a metasurface reflector. The embedded feeding source used in this study is a 2 × 2 microstrip patch array. The influence of the inter-element spacing of the patch array feed on the radiation patterns is investigated and reported. The effect of the cavity thickness is also considered. Finally, the design of highly directive subwavelength cavity antennas is presented.
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Papers by André de Lustrac