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This work addresses analysis of hybrid plasmonic/dielectric metamaterials operated in guided wave configurations in the near-infrared domain (» = 1.5 µm). The objective is to achieve an efficient control over the flow of the light in the waveguide using effective index variation induced by metasurface resonances. Specifically we consider a composite guiding structure made of a 2D plasmonic metasurface...
A gradient index dielectric metasurface composed of air holes of different dimensions in a bulk dielectric, is fabricated by three-dimensional (3D) polyjet printing and is combined with inductive and capacitive copper grids to have an LC resonance. The latter metal-dielectric metasurface is then used as a phase-gradient superstrate in a Fabry-Perot cavity at microwave frequencies. Performed simulations...
A metamaterial-based lens, calculated using transformation optics concept, is designed using electric-LC resonators. A planar microstrip antenna source is used as transverse electric polarized wave launcher for the lens. Both the far field radiation patterns and the near-field distributions have been measured to experimentally demonstrate the beam steering properties. Measurements agree quantitatively...
Non-uniform phase metasurfaces used as partially reflective surfaces are proposed to steer the radiated beam in Fabry-Perot cavity antennas. The phase modulation is achieved by varying the inductance of the LC-resonant metasurface. Depending on the phase modulation applied, steering angle can be efficiently controlled.
The emission of a radiating source is virtually delocalized through the use of transformation electromagnetics concept. The electromagnetic device able to perform such a transformation is obtained by a space compression followed by a space expansion. Moreover, the radiation pattern of the virtual source can be modified such that an omnidirectional radiation can be changed into a directive one. Theoretical...
The objective of the present work is to introduce a new concept of direct dark mode excitation mechanism in a metasurface structure. The dark mode excitation is entirely determined by structures' symmetry and does not depend on hybridization mechanism related to near-field coupling between elements. In our examples we consider single element based metasurface composed of two V nano-antennas having...
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...
Transformation optics offers an unconventional approach for the design of novel radiating devices. Here we propose an electromagnetic metamaterial able to split an isotropic radiation into multiple directive beams. By applying transformations that modify distance and angles, we show how the multiple directive beams can be steered at will. We describe transformation of the metric space and the calculation...
Complex electromagnetic structures can be designed by using the powerful tool of spatial coordinate transformation. In this study, we define a spatial coordinate transformation which shows the possibility of designing a taper between two waveguides with different dimensions; one waveguide is 11 times wider than the other. Both a continuous and a discretized model is presented and we propose achievable...
The resonant absorption in an ultrathin metamaterial is studied theoretically. We present a simple physical model describing this phenomenon based on equivalent resonant circuits. We discuss the role of radiative and dissipative damping of resonant mode supported by the metamaterial in the formation of absorption spectra. We show that the results of rigorous calculations of Maxwell equations can be...
A directional directive emission is converted into an omnidirectional one based on the transformation electromagnetics concept. A dipole antenna used as the excitation source is embedded in a bulk metamaterial presenting gradient radial and angular permittivity. Electric-LC resonators are used to produce such gradient permittivity metamaterials. Theoretical analysis is presented and numerical simulations...
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...
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...
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...
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...
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...
The study deals with the modelling, practical implementation and characterization of a directional antenna controllable through 360° in the [2 – 2.5 GHz] frequency band. The antenna is composed of a central omnidirectional broadband monopole feed surrounded by a metamaterial made of one or two controllable layers of metallic strips printed on a dielectric substrate, which can be electrically continuous...
A broadband metamaterial-based low profile antenna is presented in the 8–12 GHz frequency band. The antenna is composed of a parallel-plate TEM waveguide embedding a planar gradient index Luneburg lens and a slot Vivaldi antenna that illuminates the latter lens. The focusing condition of the lens, requiring a gradient refractive index is achieved through the use of complementary non-resonant metamaterial...
The analysis and design of a low-profile Fabry-Pérot (FP) cavity antenna comprising an active metasurface are presented. The antenna under investigation is formed by embedding a feeding source in a cavity composed of a Perfect Electrical Conductor (PEC) surface and a metasurface reflector. Several configurations of such antennas are presented to achieve different desired performances such as high...
The use of transformation optics concept for the design of miniaturized radiating devices is investigated. By choosing transformations that compress space, and then match it to the surrounding radiation environment, we are able to alter 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...
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