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Recent Advancement in Graphene-Based Metasurface Structures
Published in Angsuman Sarkar, Arpan Deyasi, Low-Dimensional Nanoelectronic Devices, 2023
Sambit Kumar Ghosh, Santanu Das, Somak Bhattacharyya
Electromagnetic metasurface, the two-dimensional equivalent of metamaterial, exhibits exotic electromagnetic (EM) properties under the incident electromagnetic wave.1 Metasurface generates great interest to the scientific community for achieving unusual properties under the incidence of electromagnetic wave because of its sub-wavelength thickness and periodicity.2–6 Metasurface manipulates the wavefront of the incoming EM wave approaching it by imposing gradient phase shift, thereby resulting in the generalized Snell’s law of light propagation.2 Electromagnetic (EM) wave analysis through the two-dimensional (2D) metasurface structures can be assumed to have a wide range of values of effective medium parameters instead of the bulk parameters. Metasurfaces have been reported for various applications including absorbers, polarization converters, antennas, filters, etc. over a broader electromagnetic spectrum.7–15
Electromagnetic Specifications and Prototype Designs of Software-Defined Surfaces
Published in Christos Liaskos, The Internet of Materials, 2020
Fu Liu, Xuchen Wang, Mohammad Sajjad Mirmoosa, Sergei Tretyakov, Odysseas Tsilipakos, Anna C. Tasolamprou, Maria Kafesaki, Alexandros Pitilakis, Nikolaos V. Kantartzis, Do-Hoon Kwon
A metasurface is an electrically thin composite material layer, designed and optimized to function as a tool to control and transform electromagnetic waves [55, 63, 78, 167, 192]. The layer thickness is small and can be considered as negligible with respect to the wavelength in the surrounding space. Recently, the emerging topic of tunable metasurfaces for wave control [38, 40, 4568, 69, 82, 106, 119, 177] has been actively advanced thanks to new possibilities for versatile and powerful control over the propagation of electromagnetic (EM) waves. Among the many available tuning mechanisms, the lumped-element enabled tunable metasurface provides the most powerful functionalities. However, the existing solutions are only using diodes or varactors, which tune only the effective surface impedance in a limited way, such as discrete values or a line in the complex impedance plane. A more general solution is to control both the real and imaginary parts of the surface impedance, i.e., tuning both the R and C parts of tuning components.
Stiff Problems: High Contrast Objects
Published in Didier Felbacq, Guy Bouchitté, Metamaterials Modeling and Design, 2017
Didier Felbacq, Frédéric Zolla, André Nicolet, Guy Bouchitté
Metamaterials or their two-dimensional analogues, metasurfaces, are generally made of basic elements containing metallic parts. The latter are generally very thin and conductive, which makes a theoretical analysis rather subtle: One cannot just let the thickness of the elements tend to zero, because the metamaterial would simply disappear in the end. In this chapter, the problem of the effective properties of a wire medium is investigated. This problem was largely discussed in the physical literature (Belov et al., 2003, 2002; Simovski and Belov, 2004). Two different approaches are proposed here. The first one deals with infinitely long wires and uses explicit calculations: It relies on the use of Green’s functions, and it can be used to deal with metasurfaces. The other approach considers the case of wires of finite length and is based on a variational approach. The main difficulty here is to identify correctly the boundary conditions at the end of the wired medium. The variational approach is very interesting because it does not require additional boundary conditions (ABC) as sometimes suggested in the electric engineering community (Maslovski et al., 2010).
A broadband stable gain antenna using nonuniform hexagonal-Slot metasurface
Published in Electromagnetics, 2022
Yue Fan, Zhi Li, Zijun Zheng, Guorui Han, Liping Han, Wenmei Zhang
In recent years, metasurface has attracted extensive attention because it could flexibly control the amplitude, phase, and polarization of electromagnetic wave. In Alharbi, Balanis, and Birtcher (2019), rectangular patches metasurface is placed in the vicinity of the square ring antenna, and a wide bandwidth of 27% with stable broadside radiation is obtained. By loading metasurface above the feeding structure, the impedance bandwidth and gain of antenna could also be improved. In Feng et al. (2017), a circular patch antenna is utilized to excite TM01 and TM02 of the nonuniform tapered metasurface. A wide impedance bandwidth of 33.1% and an average gain of 6.34 dBi are achieved. In Cao, Meng, and Shi (2019), a triple-slotted substrate integrated cavity is utilized to feed the square patches metasurface, and a wide bandwidth of 33% with minor gain ripple is realized by combining the modes of metasurface and substrate integrated cavity. In Zhang et al. (2020), hexagonal loop-shaped metasurface is excited through the coupling aperture on the ground plane. The antenna could achieve a large bandwidth of 56.3% through several modes of the metasurface. In Chen et al. (2021a, 2021b), a slot antenna is utilized to excite the hybrid metasurface and polarization-dependent metasurface, respectively. By assembling the resonant modes of metasurface and slot antenna, broadband and stable radiation could be obtained. For the aforementioned antennas, the biggest impedance bandwidth and 2 dB gain bandwidth are 57.4% and 39.2%, respectively. Therefore, broadband antenna with stable gain is a challenge for wireless communication system.
A nonuniform metasurface loaded circularly polarized differentially-fed antenna
Published in Electromagnetics, 2019
Metasurface is a 2-D metamaterial with periodic metallic structures in the sub-wavelength scales, which could generate an abrupt phase difference. Recently, metasurface has been introduced to enhance the performance characteristics of antenna, as an engineering innovation (Moreno et al. 2018; Nasser, Liu, and Chen 2018; Ni et al. 2018; Qu et al. 2018; Xu et al. 2013; Xu, Wang, and Qi 2013). For example, enhance the antenna gain and directivity (Qu et al. 2018), broaden the bandwidth (Nasser, Liu, and Chen 2018; Xu et al. 2013), reduce the mutual electromagnetic interaction (Moreno et al. 2018), and realize polarization conversion (Ni et al. 2018; Xu, Wang, and Qi 2013), etc. In this paper, metasurface with 4 × 4 nonuniform units is introduced into the slot-coupled antenna to enhance the gain, impedance bandwidth, and axial ratio bandwidth. In addition to the resonance caused by the slot-coupled antenna, a new one could be introduced by loading metasurface. The impedance bandwidth and axial ratio bandwidth could be adjusted by tuning the distance between the two resonant frequencies. The lower resonance could be changed independently by varying the length of cross slot in the metallic ground while the higher resonance remains unaltered. It is worth mentioning that there is scarce literature on the metasurface-based circularly polarized differentially-fed antenna (CPDFA). The proposed CPDFA is fabricated and measured for demonstration. Measured results exhibit that the proposed CPDFA has numerous advantages, including no air gap, low cost, low profile (0.046λ0 at 3.3 GHz), high gain, as well as stable and unidirectional radiation pattern.
Ultra-wideband radar cross-section reduction based on phase cancellation
Published in Electromagnetics, 2023
Baoqin Lin, Wenzhun Huang, Jianxin Guo, Xiang Ji, Yan Zhou, Yunyan Wu
With the development of radar detection technology, the demand of radar cross section (RCS) reduction is getting higher and higher. How to reduce the RCS of various targets is always a research hot-spot in electromagnetism domain. Metasurface is an artificial composite surface composed of sub-wavelength resonant unit structures, which can provide a convenient way to manipulate electromagnetic wave. Due to the favorable performance, metasurface can be used to reduce the RCS of various targets.