Hannan Saif, Islam Mohammad Tariqul, Almutairi Ali F, Faruque Mohammad Rashed Iqbal
Department of Electrical, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, Bangi, 43600, Selangor, Malaysia.
Electrical Engineering Department, College of Engineering and Petroleum, Kuwait University, Safat, 13060, Kuwait.
Sci Rep. 2020 Jun 25;10(1):10338. doi: 10.1038/s41598-020-67262-5.
In this paper, a wide bandwidth angle- and polarization-insensitive symmetric metamaterial (MM) absorber for X and Ku band is proposed. For both normal and oblique incidence in TEM mode, the proposed unit cell shows high absorption at different polarizing angles due to structural symmetry. A four-fold resonator was introduced in the unit cell to enhance the bandwidth. The performance of the proposed absorber is determined by both full-wave simulations and measurements. The simulated and measured absorptions are almost similar at normal incidence with 94.63%, 95.58%, 97% and 75.58% at 11.31 GHz, 14.11 GHz, 14.23 GHz, and 17.79 GHz respectively. At 45° for these frequencies, the absorptions are 95.47%, 97.2%, 97.12% and 75.29% respectively. For 90°, the absorptions are similar to those for 45° except 98.15% for 14.21 GHz. At all these angles and resonance frequencies, either permittivity or permeability was found negative, as a result, the refractive index was negative revealing metamaterial characteristics of the unit cell. Along with high absorptivity and wide incidence angle insensitivity up to 90°, a total of 1.42 GHz of absorption bandwidth was achieved, which is better than recent similar works with FR4 substrate.
本文提出了一种用于X波段和Ku波段的宽带宽角度和偏振不敏感对称超材料（MM）吸收器。对于TEM模式下的垂直入射和斜入射，由于结构对称性，所提出的单元胞在不同偏振角度下均表现出高吸收率。在单元胞中引入了一个四重谐振器以拓宽带宽。所提出的吸收器的性能通过全波模拟和测量来确定。在垂直入射时，模拟和测量的吸收率几乎相似，在11.31 GHz、14.11 GHz、14.23 GHz和17.79 GHz处分别为94.63%、95.58%、97%和75.58%。在这些频率下，45°入射角时的吸收率分别为95.47%、97.2%、97.12%和75.29%。对于90°入射角，除了14.21 GHz处的吸收率为98.15%外，其他频率下的吸收率与45°入射角时相似。在所有这些角度和共振频率下，均发现介电常数或磁导率为负，因此，折射率为负，这揭示了单元胞具有超材料特性。除了高达90°的高吸收率和宽入射角不敏感性外，还实现了总计1.42 GHz的吸收带宽，这比最近使用FR4基板的类似工作要好。
