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In this work the design of an ultrathin carpet cloak based on a metasurface with ring resonators is demonstrated. The scattering from a triangular bump of a Gaussian beam is suppressed by manipulating the reflection phase along the edge of the bump. This is achieved by an array of closed ring resonators with varying radii. The object to hide can be placed under the bump on a flat ground plane. The...
Gradient metasurfaces have recently received significant attention for the unique opportunities they offer for advanced wave manipulation. Such metasurfaces are usually discrete implementations of surface impedance profiles, which are analytically derived to yield the desired operation. Several recent numerical and experimental studies have shown that gradient metasurfaces can work very well over...
Here we present the design and numerical results for an ultrathin unidirectional carpet cloak based on the restoration of the phase of the reflected wave. This ultrathin carpet cloak conceals a triangular surface bump with center height of 4.1 mm and tilt angle of 20 deg. The cloaking metasurface consists of an array of closed ring resonators, which allow an efficient phase manipulation along the...
Optical metasurfaces, or planarized metamaterials, are based on engineered subwavelength inclusions intentionally designed to provide desired advanced functionalities, unavailable with conventional gratings, by exploiting their anomalous localized response. Metasurfaces have been investigated both theoretically and experimentally in various recent studies, but most of the available examples are limited...
We analyze the constraints governing absorption and scattering of arbitrary sensors or receiving antennas. Our findings bring forward interesting physical limitations on the amount of accessible absorption in a low-scattering sensor and suggest practical ways to achieve efficient designs for noninvasive sensors, based on the application needs. A subwavelength dipole antenna is studied as a numerical...
In this work we show that two conjoined subwavelength cap-shaped structures may be used as an efficient energy-harvesting nanostructure with unbounded absorption efficiency. Following an analytical method based on coordinate transformation, we show that anomalous plasmonic resonances arise when one of the two nanostructures is plasmonic, resulting in adiabatic focusing of surface plasmons toward the...
In this work, the authors proposed and modeled a phase shifter-less phased array receiver. In the front-end of the array, the harmonic mixing of the spatially distributed local oscillator (LO) signal with the incident RF signal produces the required intermediate frequency (IF) signal. For beamsteering, only the LO feed antenna is to be scanned mechanically. This reduces the complexity and thus the...
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