Stephen Lincy, Yogesh N, Subramanian V
Microwave Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India.
Department of Nuclear Physics, School of Physical Sciences, University of Madras, Chennai, 600025, India.
Sci Rep. 2019 Jul 11;9(1):10058. doi: 10.1038/s41598-019-46464-6.
The ever-increasing interest towards metamaterial absorbers owes to its remarkable features such as ultra-thin nature and design flexibility. Subduing the inherent narrow bandwidth of such absorbers is the prime goal in metamaterial absorber research, as this can widen the applications areas. A greater challenge is to construct bidirectional absorber, which provides direction-insensitive absorption, as most of the existing designs exhibit single sided absorption due to the complete metal film used in the design. This work presents the realization of a bidirectional, bandwidth-enhanced metamaterial absorber with basic elements such as strips and squares optimized to have adjacent resonances leading to a bandwidth-enhanced absorption. The structural evolution of the constituent metallic components towards the formation of bandwidth-enhanced absorption is described. The bidirectional absorber exhibits more than 90% absorption between 13.40 GHz and 14.25 GHz from the two incident directions. The mechanism of absorption is studied with the surface current analysis and the effective parameters of the structure. The choice of the metallic components with four-fold rotation symmetry renders the proposed design to be polarization independent and wide-angle receptive. The numerical studies are verified experimentally at microwave frequencies, which shows a good agreement between them.
对超材料吸波器日益增长的兴趣源于其超薄特性和设计灵活性等显著特点。克服此类吸波器固有的窄带宽是超材料吸波器研究的主要目标，因为这可以拓宽应用领域。一个更大的挑战是构建双向吸波器，即提供对方向不敏感的吸收，因为现有的大多数设计由于在设计中使用了完整的金属薄膜而表现出单面吸收。这项工作展示了一种双向、带宽增强的超材料吸波器的实现，其基本元件如条形和方形经过优化，具有相邻的共振，从而实现带宽增强的吸收。描述了组成金属部件朝着形成带宽增强吸收的结构演变。该双向吸波器在13.40 GHz至14.25 GHz之间从两个入射方向表现出超过90%的吸收。通过表面电流分析和结构的有效参数研究了吸收机制。具有四重旋转对称性的金属部件的选择使所提出的设计具有偏振无关性和广角接收性。数值研究在微波频率下进行了实验验证，结果表明两者之间具有良好的一致性。
