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A planar reconfigurable metasurface is used as a parabolic reflector for antenna applications. The metasurface is composed of unit cells incorporating voltage-controlled varactor diodes, where the dispersion responses of the cells can be tailored. The phase characteristics of a parabolic reflector is engineered by judiciously controlling the bias voltage of the varactor diodes on the planar metasurface...
We introduce a novel class of dark modes for electromagnetically induced transparency. These dark modes depend on both near-field and far-field coupling between resonators. As an example, a planar metasurface composed of a bilayer of metallic Z-shaped meta-atoms is investigated. Performed simulations and measurements show the appearance of sharp Fano resonances.
An active metasurface is used as a reconfigurable reflectarray antenna. The metasurface is composed of unit cells incorporating voltage-controlled varactor diodes, where the dispersion responses of the cells can be tailored. A prototype is fabricated and far-field antenna measurements are performed. We experimentally demonstrate frequency agility over a broad frequency range and beam scanning mechanisms.
All-dielectric devices are designed using Quasi-Conformal Transformation Optics (QCTO) concept and fabricated by additive manufacturing for the control of wave propagation. Three lenses are studied; the first one is used to compensate for the curvature of a non-planar antenna array, the second one to steer an electromagnetic beam and the last one to concentrate an electromagnetic field.
The engineering of metasurfaces for antenna and sensing applications is studied. The metasurfaces composed of LC-resonant cells, are designed to achieve either phase modulation or high quality factor resonances. While the phase modulated metasurface used as a superstrate in a Fabry-Perot cavity antenna, shows the capability to steer the radiated beam to an off-normal radiation, the high quality factor...
A miniaturized antenna using a matching circuit with Non-Foster elements is described. Such active external matching circuit allows a commercial antenna whose frequency range is 950–1260 MHz to operate at lower frequencies (about 125 MHz) with a relative bandwidth of 40%. Analytical study was used to design the active circuit and then to implement it. Simulation and measurement results show similar...
Quasi-conformal transformation optics (QCTO) is applied to design electromagnetic lenses for focusing and collimating applications at microwave frequencies. Two devices are studied and conceived by solving the Laplace's equation that describes the deformation of a medium in a space transformation. The first lens is applied to produce an overall directive in-phase emission from an array of sources...
Based on transformation electromagnetics concept, the design procedure of a lens antenna, which steers the radiated beam of a primary source, is presented. Laplace's equation is adopted to construct the mapping between the virtual space and the physical space. Full wave simulations are performed to validate the model. The numerical results show that, when placing the lens antenna above a microstrip...
It has been recently shown that a metasurface presenting a phase-gradient can be effectively used as a partially reflecting surface (PRS) in a Fabry-Perot leaky wave antenna to produce beam steering. The aim of the present contribution is to develop and present an analytical model which will allow us to predict the angle of deflection.
In this paper, based on quasi-conformal transformation optics (QCTO), a synthesis design of a conformal array radiation enhanced by an all-dielectric metamaterial lens is presented. For the two-dimensional TE polarization, a physically cylindrically conformed patch array can acquire the same radiating features of a virtual planar focusing patch array, using a lens having only nonmagnetic medium parameters...
A single-sized dielectric cylinder-based metamaterial is fabricated from TiO2 nanoparticles, using a bottom-up approach. The sub-elements constituting the metalayer are embedded in a nonmagnetic transparent host matrix in the microwave regime and arranged in a square lattice. We demonstrate numerically and experimentally a broadband magnetic activity. The key feature to achieve this performance remains...
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...
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...
Gradient index lenses are proposed to transform a cylindrical wave into a plane one. The lenses are designed from metamaterials engineering in a wide frequency band. A primary source operating in the whole X-band is used to feed the lenses. The lens-antenna systems are low profile and exhibit a directive emission in the H-plane. A very good agreement is observed between measurements performed on the...
In this paper, a new concept of directive planar waveguide (WG) antenna array for the next generation of point to point E-band communication is presented. The proposed antenna consists of two major parts; firstly the array of Gaussian horn radiating elements and secondly the mixed feeding rectangular WG network. The feeding network is composed of a mixed 1∶8 power distribution waveguide spliters....
The modelling, practical implementation and characterisation of an ultra-directive antenna around 10 GHz are presented. The design of the antenna is based on the 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...
In this paper we introduce the design, fabrication and characterization of an ultra-directive source obtained by transforming the electromagnetic radiation path of an isotropic emitter. Near-field cartography of the emitted radiation and far field measurements of the radiation pattern are performed to illustrate the performances of our device.
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