A tunable ultra-wideband metamaterial absorber based on graphene
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A tunable ultra‑wideband metamaterial absorber based on graphene Liansheng Wang1 · Dongyan Xia2 · Quanhong Fu3 · Xueyong Ding1 · Yuan Wang1 Received: 20 February 2020 / Accepted: 18 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract A tunable ultra-wideband metamaterial absorber based on graphene is presented herein. Its absorption exceeds 90% from 1.57 to 8.46 GHz when the Fermi level of the graphene is 0.7 eV, and it can be tuned by changing the bias voltage applied on the graphene. To explore the mechanism of its wideband absorption and tunability, the surface current of the metamaterial absorber at given absorption frequency is monitored for different Fermi levels. Further simulation results indicate that the absorption by the metamaterial absorber is insensitive to the polarization state of the incident wave but sensitive to its angle of incidence. The absorber offers the advantages of simplicity, ultra-wideband operation, and tunable absorption, having potential applications in the fields of electromagnetic stealth technology, detectors, and communication. Keywords Graphene · Ultra-wideband · Tunable · Conductivity · Metamaterial absorber
1 Introduction Metamaterial absorbers were first proposed by Landy of Boston University in 2008 [1], based on a design principle in which the equivalent permittivity is made equal to the equivalent permeability by designing a metamaterial structure, to achieve impedance matching with free space and thereby reduce the reflection of incident waves. Because of their great potential for application in the fields of stealth technology [2], detection [3], and communication [4], such absorbers have become a metamaterial research hotspot. With the development of such research, the absorption of metamaterial absorbers has gradually been expanded from the microwave to the terahertz [5], infrared [6], and optical ranges [7], from single [1] to dual [8] and multiple frequencies [9], as well as broadband operation [10]. The absorption bandwidth is an important technical index for metamaterial absorbers, and the use of a frequency-selective surface exhibiting a strong ohmic loss effect is an important method * Liansheng Wang [email protected] 1
Department of Science and Technology, Sanya University, Sanya 572022, Hainan, China
2
Department of Finance and Economics, Sanya University, Sanya 572022, Hainan, China
3
Department of Science, Northwestern Polytechnical University, Xi’an 710072, Shanxi, China
to achieve metamaterials with wideband absorption [11, 12]. However, tunable wideband metamaterial absorber would have even greater practical application value. Based on the above-mentioned method of using a strong ohmic loss effect to achieve a metamaterial with wideband absorption, Wang et al. [13] proposed in 2016 a tunable wideband metamaterial absorber with absorption exceeding 90% from 1.6 to 8 GHz by loading a variable resistance and inductance in the gap of the unit cell. In 2007, An et al. [14] designed a tunable wideband metama
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