An optically transparent metasurface for broadband microwave antireflection

Abstract

Metamaterial absorbers and diffusers provide powerful routes to decrease the backward reflection significantly with advantages of ultrathin profile and customized bandwidth. Simultaneous control of the absorption and scattering behaviors of the metamaterials which helps to improve the suppression capabilities of backward reflection, however, still remains a challenge. Aiming at this goal, we propose a metasurface constituted by two kinds of elements in a pseudorandom arrangement. By the use of indium tin oxide with moderate sheet resistance in the meta-atoms, enhanced absorption of energy can be achieved in a broad spectrum when interacted with illuminated waves. In the meanwhile, electromagnetic diffusion will be invoked from the destructive interference among the elements, giving rise to significant reduction of specular reflection as a result. Excellent agreements are observed between simulation and experiment with pronounced reflection suppression from 6.8 GHz to 19.4 GHz. In addition, the optical transparence of the patterns and substrates makes the proposed metasurface a promising candidate for future applications like photovoltaic solar cells and electromagnetic shielding glasses.

Broadband RCS Reduction by a Quaternionic Metasurface

“…Based on this idea, the unit cells of metasurfaces with different phases are coded, designed, and programmed to show highly designable scattering patterns, including the ones that show extremely low radar observability [ 25 , 26 , 27 , 28 ]. The RCS reduction metasurfaces makes use of phase difference of neighboring unit cells other than the strong resonant absorption, granting them much broader working bandwidth and lower profile with respect to metamaterial absorbers [ 29 , 30 ]. For example, Cui et al proposed a metasurface that composed of different square patches with a thickness of only 1.985 mm to exhibit a −10 dB RCS reduction in the frequency range of 7.8–12 GHz [ 31 ].…”

Optically and radio frequency (RF) transparent meta-glass

“…Recent years have witnessed a growing interest in thin metallic nano-films that can simultaneously offer high electrical conductivity and optical transparency, owing to their promising potential in realizing various optically transparent electromagnetic (EM) devices and low-emissivity materials. In this regard, conductive oxides (e.g., indium tin oxide (ITO), aluminum-doped zinc oxide (AZO)) and dielectric-metal-dielectric (DMD) designs (usually comprising silver nano-films) have been extensively studied [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] for a variety of applications. These include lowemissivity optical coatings [1-3, 16, 19, 20], transparent conductive oxides (TCOs) in photovoltaic devices [2][3][4], transparent circuit components [4], antennas [5], metamaterials [7-10, 17, 20, 21], and various flexible devices and sensors [11,12,18].…”

Optically transparent and single-band metamaterial absorber based on indium-tin-oxide

“…Indium‐tin‐oxide (ITO) films represent great infrared reflectors and are transparent at visible wavelengths. They have also been used as resistive films in metamaterials due to the commercial availability, low cost, and good mechanical flexibility . However, ITO‐based MAs have been intensively studied at microwave frequencies, whereas their applications in THz frequencies have not been properly studied.…”

“…However, ITO‐based MAs have been intensively studied at microwave frequencies, whereas their applications in THz frequencies have not been properly studied. Moreover, most of the reported ITO‐based MAs are wideband absorbers, whereas some of the transparent applications, for example, EM shielding glasses for a certain frequency, require single‐ or multi‐band absorbers.…”

“…They have also been used as resistive films in metamaterials due to the commercial availability, low cost, and good mechanical flexibility. [24][25][26][27][28] However, ITO-based MAs have been intensively studied at microwave frequencies, 25,26 whereas their applications in THz frequencies have not been properly studied. Moreover, most of the reported ITO-based MAs are wideband absorbers, 27,28 whereas some of the transparent applications, for example, EM shielding glasses for a certain frequency, require single-or multiband absorbers.…”