Resonant metasurface with tunable asymmetric reflection

Abstract

Suppression of backscattered electromagnetic waves by carefully designed structures is highly demanded in a range of applications, some of which are radar invisibility, antenna isolation, and many others. Salisbury screens, composed of a mirror with an additional layer on top, are traditionally used for these purposes. Here, we report on the design and experimental demonstration of a reciprocal screen, which demonstrates asymmetric reflection properties when illuminated from opposite directions. The structure utilizes near-field magneto-electric coupling between subwavelength split ring resonators and wires, forming a metasurface. While the reciprocal structure demonstrates perfect symmetry in transmission, strong backscattered asymmetry is shown to be controllable by carefully choosing the Ohmic losses, which are implemented with lumped resistors soldered into the resonators. Depending on the load, the meta-screen demonstrates switching properties that vary between fully symmetric and completely asymmetric reflection between the forward and backward directions of incident illumination. The frequency selective surface acts as a Huygens element when illuminated from one side and as a perfect mirror when illuminated from the other. The ability to tailor the asymmetric reflectance of electromagnetic metasurfaces by controlling Ohmic losses allows employing additional degrees of freedom in designing of radomes and other antenna devices. Furthermore, the concept could be extended to optical frequencies, where resistive losses can be controlled via direct carrier injection into semiconductor devices.

Coupled micro-Doppler signatures of closely located targets

“…1. Similar notations were used in 27,28 , which contains the detailed mathematical formulation. While both particles are assumed to possess the same polarizability, they are modulated with different frequencies Ω 1 and Ω 2 .…”

Electrically Tunable Left-Handed Textile Metamaterial for Microwave Applications

“…They can be integrated with antennas to produce customised reactions and mode tuning. Different methods have been developed and are either based on loops (magnetic resonators), wires (electric), and their combinations [ 4 , 5 ]. Besides, researchers have employed MTMs in applications such as invisibility cloaking [ 6 , 7 ], wireless health monitoring [ 8 ], filters [ 9 ], sensors [ 10 ], bendable artificial magnetic conductors (AMC) [ 11 ], radio-frequency identification (RFID) tags [ 12 ], and electromagnetic wave absorbers [ 13 ].…”

The Quantum Optics of Asymmetric Mirrors With Coherent Light Absorption

“…Instead, for mirror interfaces with coherent light absorption, we have r a ≠ r b (Monzón and Sánchez-Soto, 1995;Barnett et al, 1998;Uppu et al, 2016). In the literature, interfaces with this property are usually referred to as asymmetric mirrors, since they break the forwardbackward scattering symmetry of conventional semitransparent mirrors (Schwanecke et al, 2008;Plum et al, 2009;Zhukovsky et al, 2009;Tumkur et al, 2012;Xu and Lezec, 2014;Kenanakis et al, 2015;Filonov et al, 2018). An alternative way of breaking the symmetry of ideal mirrors, i.e., without the introduction of absorbing layers, is to use surface roughness.…”