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International audience; The broadband directive emission from the use of waveguided metamaterials is numerically and experimentally reported. The metamaterials, which are composed of non-resonant circular complementary closed ring structures printed on a dielectric substrate, are designed to obey the refractive index of a Luneburg lens. An arc array of planar radiating slot antennas placed at the periphery of the lens is used as wave launchers. A prototype of the lens associated with the feed structures has been fabricated using standard lithography techniques. To experimentally demonstrate the broadband focusing properties and directive emissions, far-field radiation patterns have been measured. Furthermore, this metamaterial-based lens can be used to achieve beam-scanning with a coverage of up to 120 degrees. Far-field measurements agree qualitatively with calculated near-field distributions. (C) 2014 AIP Publishing LLC.

29th URSI General Assembly and Scientific Symposium (URSI GASS), Beijing, PEOPLES R CHINA, AUG 16-23, 2014; International audience; A metamaterial surface composed of non-resonant circular complementary closed ring resonators is designed to obey the refractive index of a Luneburg lens. An array of planar slot antennas placed at the periphery of the lens is used at wave launchers. A prototype of the lens associated with the feed structures has been fabricated using standard printed circuit board (PCB) technology. Measured far-field radiation patterns have shown directive beams in H-plane over the [8 GHz - 12 GHz] frequency range. Furthermore, this metasurface lens antenna has demonstrated beam-scanning with a coverage of up to 120 degrees. Far-field measurements agree qualitatively with calculated near-field distributions.

International Workshop on Antenna Technology - Small Antennas, Novel EM Structures and Materials, and Applications (iWAT), Sydney, AUSTRALIA, MAR 04-06, 2014; International audience; Metasurfaces presenting a phase-gradient are designed at 10 GHz and are proposed to steer an antenna's radiated beam from broadside towards endfire direction. The metasurfaces are composed of both inductive and capacitive grids and the phase-gradient is achieved by modifying the elements in the inductive grid. Such phase-gradient metasurfaces are utilized as Partially Reflecting Surfaces (PRS) in Fabry-Perot (FP) leaky-wave antennas (LWAs). Depending on the gradient used, beam steering up to 60 degrees has been observed numerically and verified experimentally.

International audience; The design of a locally one-dimensional inductive-varying metamaterial operating near 10 GHz is reported. This is combined with a fixed capacitive grid to design a phase-varying metasurface. This composite metasurface is then used as a partially reflecting surface (PRS) together with a perfect electric conductor surface to form a resonant Fabry-Perot type cavity. A patch antenna acting as a primary source is embedded in the cavity to constitute a highly beam-steerable directive antenna. A 56 degrees deflection of the antenna beam is experimentally observed.

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.

A low-profile substrate-integrated lens antenna is designed using planar metamaterials for a broadband operation. The lens antenna is based on embedding a Vivaldi source inside a parallel-plate waveguide to illuminate a half Maxwell fish-eye (HMFE) lens operating in X-band. The focusing condition of the lens, requiring a gradient refractive index is achieved through the use of complementary non-resonant metamaterial structures. Far-field radiation patterns have been measured on a fabricated prototype in an anechoic chamber. It has been shown that the proposed planar antenna presents good focusing properties.

A metamaterial-based low profile antenna is presented in the 8-12 GHz frequency range (X-band). The antenna is designed in a parallel-plate TEM waveguide configuration. A planar metamaterial-based Luneburg lens and a Vivaldi antenna that illuminates the latter lens are embedded inside the TEM waveguide. The focusing condition of the lens, requiring a gradient refractive index is achieved through the use of complementary non-resonant metamaterial structures. Numerical simulations are performed to determine the suitable unit cells geometry with respect to the wave launcher. A prototype has been fabricated using standard printed circuit board techniques and has been measured in an anechoic chamber. A good qualitative agreement is observed between simulations and experiments. The proposed planar antenna presents good focusing properties over the X-band frequency range.

A low-profile substrate-integrated lens antenna is designed using planar metamaterials for a broadband operation. The lens antenna is based on embedding a Vivaldi antenna source inside a parallel-plate waveguide to illuminate a half Maxwell fish-eye (HMFE) lens operating in X-band. The focusing condition of the lens, requiring a gradient refractive index is achieved through the use of complementary nonresonant metamaterial structures. Numerical simulations are performed to determine the suitable unit cells geometry with respect to the wave launcher inserted into the parallel-plate waveguide. The electric field distribution inside the antenna system has also been explored numerically. Far-field radiation patterns have been measured on a fabricated prototype in an anechoic chamber. It has been shown from both near- and far-field plots that the proposed planar antenna presents good focusing properties.

International audience; A high-gain low-profile Fabry-Perot (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 lambda(0)/6 (where lambda(0) 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 degrees can be obtained when judiciously designing the inductive grid of the PRS.

7th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics (METAMATERIALS), Bordeaux, FRANCE, SEP 16-19, 2013; International audience; A planar Z-shaped meta-atom has been recently proposed as an alternative design to the conventional electric-LC (ELC) resonator for achieving negative permittivity. Transforming the LC topology of the resonator helps to facilitate transposition of geometrical parameters for the optical regime and also to improve the metamaterial homogeneity. In this work, we discuss about the interpretation of the resonance in such Z-shaped meta-atom.

Various easy made planar electric meta-atoms are presented as alternative designs to the conventional electric-LC resonator for achieving negative permittivity. Transforming the LC topology of the resonator helps to facilitate transposition of geometrical parameters for the optical regime and also to improve the metamaterial homogeneity. Our approach aims to simplify the resonator design and achieve a lower resonance frequency without being limited by fabrication techniques. A parametric sweep is performed to evaluate the influence of the different geometrical parameters on the resonance frequencies of the meta-atoms. The electromagnetic behavior is investigated through both simulations and experiments in the microwave regime. Our results show that the developed meta-atoms exhibit a purely strong electric response to normally incident radiation and can be used very effectively in producing materials with negative permittivity. For instance, a Z-shaped structure is shown to present a higher effective medium ratio. The proposed meta-atoms can find various applications

A Z-shaped easy made planar meta-atom is presented as an alternative design to the conventional electric-LC (ELC) resonator for achieving negative permittivity. Transforming the LC topology of the resonator helps to facilitate transposition of geometrical parameters for the optical regime and also to improve the metamaterial homogeneity. Our approach aims to simplify the resonator design and achieve a lower resonance frequency without being limited by fabrication techniques. The electromagnetic behaviour is investigated through both simulations and experiments in the microwave regime. Our results show that the developed meta-atom exhibits a strong electric response to normally incident radiation and can be used very effectively in producing materials with negative permittivity. The Z-shaped structure is also shown to present a higher effective medium ratio and can possibly find various applications in planar high frequency passive circuits due to the simplicity of fabrication.

A printed Z-shaped electric meta-atom is presented as an alternative design to the conventional electric-LC (ELC) resonator. We propose to redesign the ELC resonator pattern to get a compact and a low cost electric resonator exhibiting a strong electric response. Our approach consists in redressing the resonator shape to accommodate higher inductance and therefore leading to a lower resonance frequency without being limited by fabrication tolerances. Simulation and measurement results show that the Z metaatom exhibits an electric response to normally incident radiation and can be used very effectively in producing materials with negative permittivity.

A printed Z-shaped electric meta-atom is presented as an alternative design to the conventional electric-LC (ELC) resonator. We propose an easy way to redesign the ELC resonator pattern to get a compact and a low cost electric resonator exhibiting a strong electric response. Our approach involves, in the effective medium regime, redressing the resonator shape to accommodate higher inductance and lead to a lower resonance frequency without being limited by fabrication tolerances. The electromagnetic behaviour of the meta-atom has been investigated through both simulations and experiments in the microwave regime. Our results show that the Z meta-atom exhibits an electric response to normally incident radiation and can be used very effectively in producing materials with negative permittivity. The proposed planar meta-atom can find various applications in high frequency passive circuits which are designed in planar technology. Moreover, the proposed structure can be scaled to much higher frequencies via appropriate lithographic scaling.

A compact and small electric-size aperture directive broadband Luneburg lens antenna is presented. The substrate-integrated lens antenna is based on embedding a Vivaldi antenna source inside a parallel-plate waveguide to illuminate a Luneburg lens operating in X-band. The focusing condition of the lens, requiring a gradient refractive index, is achieved through the use of complementary nonresonant metamaterial structures. Numerical simulations are performed to determine the suitable unit cells geometry with respect to the wave launcher inserted into the parallel-plate waveguide. A prototype fabricated using standard printed circuit board techniques has been measured in an anechoic chamber. The electric field distribution inside the antenna system has also been explored using a two-dimensional near-field microwave scanning setup. A good qualitative agreement is observed between simulations and experiments. It has been shown from both far- and near-field measurements that the proposed planar antenna presents good focusing properties.