The SSPP performance can be affected by adjusting and controlling the length of horizontal metallic strip affects the impedance matching of electromagnetic wave, so its adjustment and control will also affect the SSPP performance, which, therefore can be improved by optimizing the longitudinal profile of strips. Hence, a number of methods for reducing thickness of metamaterials were proposed such as introducing meandered strip structure, increasing high duty ratio of metal strips and loading other absorbing materials. As metal strips increase, absorption bandwidth increases and metamaterials get thicker. It is worth noting that a longitudinal array of metallic strips overlapping with periodic arrangement can be combined with adjacent absorption peaks into a continuous adsorption peak. Therefore, SSPP has been extensively used as absorbing metamaterials by a lot of researchers. Additionally, SSPP as absorbing metamaterial has also been applied in terahertz and infrared stealth. With the development of researches, the properties in the local field enhancement, strong dispersion and deep subwavelength characteristics of SSPP are widely applied in microwave absorbing, stealth and dispersion engineering. Subsequently, the SSPP of Transverse Magnetic(TM) and Transverse Electric(TE) were obtained by metamaterial. Exhibiting similar properties to Surface Plasmon Polariton (SPP) in optics, SSPP is an electromagnetic mode excited by artificial electromagnetic medium or structure in the microwave band. On this basis, Pendry first proposed Spoof Surface Plasmon Polariton (SSPP) in earlier researches. Originated from optics, Surface Plasmon Polariton (SPP) is a transmission mode that is generated by the tight coupling between the electromagnetic (EM) wave and surface electron. A significant breakthrough has been made for wave absorption thanks to the rapid development of electromagnetic metamaterials. Metamaterials composed of artificially engineered subwavelength inclusions exhibit novel properties that cannot be found in nature or difficult to achieve. The electromagnetic wave transmission can be effectively suppressed by electromagnetic absorbers, which is why they can be widely applied in radar stealth techniques, electromagnetic protection, and wireless transmission. This method provides an efficient approach to the design of radar absorbing structures and can also be extended to optimized design of other metamaterials. The simulated and measured results show that the absorbance is higher than 90% in 10–30 GHz, which convincingly verifies the effectiveness of this method. As an example, a wideband APS is demonstrated using this method. Our investigation shows that non-linear variation of the strip lengths will make better k-matching and wideband absorption. The APS unit cell is composed of a longitudinal array of metallic strips, the length profile of which can be optimized to improve k-matching between free-space waves and SSPPs and meanwhile to customize absorption at each frequency within a wide band. In this paper, we propose a method of optimizing the longitudinal profile of APS based on Genetic Algorithm (GA), with the aim of obtaining high-efficiency wideband absorption of EM waves. In particular, the profile of an absorbing plasmonic structure (APS) plays an important role in realizing its wideband absorption performance. Plasmonic structures that support the spoof surface plasmon polariton (SSPP) mode can be tailored to achieve strong absorption of electromagnetic (EM) waves. Department of Basic Sciences, Air Force Engineering University, Xi'an, China.
Ruichao Zhu, Jiafu Wang *, Sai Sui *, Yueyu Meng, Tianshuo Qiu, Yuxiang Jia, Xiaofeng Wang, Yajuan Han, Mingde Feng, Lin Zheng and Shaobo Qu
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