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Tichit P.-H.,University Paris - Sud | Burokur S.N.,CNRS Mechanical Energy and Electromagnetism Lab | De Lustrac A.,University Paris - Sud
Optics Express | Year: 2011

Using the idea of wave manipulation via transformation optics, we propose a way to create a quasi-perfect isotropic emission from a directional one. The manipulation is enabled by composite metamaterials that correspond to a space stretching around the source. It is shown that the directive radiation of a plane source larger than the operating wavelength can be transformed into an isotropic one by modifying the electromagnetic properties of the space around it. A set of parameters allowing practical realization of the proposed device is defined. Numerical simulations using Finite Element Method (FEM) are performed to illustrate the proposed coordinate transformation. This idea, which consists in strongly reducing the apparent size of a radiating source, can find various applications in novel antenna design techniques. © 2011 Optical Society of America.

Burokur S.N.,CNRS Fundamental Electronics Institute | Burokur S.N.,CNRS Mechanical Energy and Electromagnetism Lab | Daniel J.-P.,ADVANTEN | Ratajczak P.,Orange S.A. | De Lustrac A.,CNRS Fundamental Electronics Institute
Applied Physics Letters | Year: 2010

The directive emission from a bilayered metamaterial surface is numerically and experimentally reported. The LC-resonant metasurface is composed of both a capacitive and an inductive grid constituted by copper strips printed on both sides of a dielectric board. By the incorporation of varactor diodes in the capacitive grid, resonance frequency and phase characteristics of the metamaterial can be tuned. The tunable phase metasurface is used as a partially reflecting surface in a Fabry-Perot resonance cavity. Far field radiation patterns obtained by direct measurements show the reconfigurability of emission frequency while maintaining an enhanced directivity. © 2010 American Institute of Physics.

Ghasemi A.,University Paris - Sud | Burokur S.N.,University Paris - Sud | Dhouibi A.,University Paris - Sud | De Lustrac A.,CNRS Mechanical Energy and Electromagnetism Lab
IEEE Antennas and Wireless Propagation Letters | Year: 2013

A high-gain low-profile Fabry-Pérot (FP) leaky-wave antenna (LWA) presenting one-dimensional high beam steering properties is proposed in this letter. The structure consists of a ground plane and a varying inductive partially reflective surface (PRS). A microstrip patch antenna is embedded into the cavity to act as the primary feed. As design examples, antennas are designed to operate at 9.5 GHz. Subwavelength FP cavities with fixed overall thickness of λ0/6 (where λ0 is the free-space operating wavelength) are fabricated and measured. The impact of varying the PRS inductance is analyzed. It is shown that a high beam steering angle from broadside toward endfire direction close to 60° can be obtained when judiciously designing the inductive grid of the PRS. © 2002-2011 IEEE.

Lezgy-Nazargah M.,Hakim Sabzevari University | Vidal P.,CNRS Mechanical Energy and Electromagnetism Lab | Polit O.,CNRS Mechanical Energy and Electromagnetism Lab
Composite Structures | Year: 2013

This study deals with static, free vibration and dynamic response of functionally graded piezoelectric material (FGPM) beams using an efficient three-nodded beam element. This beam finite element is based on a refined sinus model. It does not require shear correction factor and ensures continuity conditions for displacements, transverse shear stresses as well as boundary conditions on the upper and lower surfaces of the FGPM beam. This conforming finite element does not suffer from shear locking. The number of the mechanical unknowns is independent of the number of layers. A high-order electrical potential field is considered through each graded piezoelectric layer. The proposed FE is validated through static, free vibration and dynamic tests for FGPM beams. For various electrical and mechanical boundary conditions, excellent agreement is found between the results obtained from the proposed formulation and reference results from open literature or 3D FEM. © 2013 Elsevier Ltd.

Dhouibi A.,CNRS Mechanical Energy and Electromagnetism Lab | Nawaz Burokur S.,University Paris - Sud | De Lustrac A.,University Paris - Sud | Priou A.,CNRS Mechanical Energy and Electromagnetism Lab
Applied Physics Letters | Year: 2013

The broadband directive emission from a metamaterial surface is numerically and experimentally reported. The metasurface, composed of non-resonant complementary closed ring structures, is designed to obey the refractive index of a half Maxwell fish-eye lens. A planar microstrip Vivaldi antenna is used as transverse magnetic polarized wave launcher for the lens. A prototype of the lens associated with its feed structure has been fabricated using standard lithography techniques. To experimentally demonstrate the broadband focusing properties and directive emissions, both the far-field radiation patterns and the near-field distributions have been measured. Measurements agree quantitatively and qualitatively with theoretical simulations. © 2013 American Institute of Physics.

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