An ultrathin and flexible metamaterial absorber (MA) with triple absorption peaks is presented in this paper. The proposed absorber has been designed in such a way that three absorption peaks are located at 8.5, 13.5, and 17 GHz (X and Ku bands) with absorption of 99.9%, 99.5%, and 99.9%, respectively. The proposed structure is only 0.4 mm thick, which is approximately 1/88, 1/55, and 1/44 for the respective free space wavelengths of absorption frequency in various bands. The MA is also insensitive due to its symmetric geometry. In addition, the proposed structure exhibits minimum 86% absorption (TE incidence) within 60° angle of incidence. For TM incidence, the proposed absorber exhibits more than 99% absorptivity up to 60° incidence. Surface current and electric field distributions were investigated to analyze the mechanism governing absorption. Parameter analyses were performed for absorption optimization. Moreover, the performance of the MA was experimentally demonstrated in free space on a sample under test with 20 × 30 unit cells fabricated on a flexible dielectric. Under normal incidence, the fabricated MA exhibits near perfect absorption at each absorption peak for all polarization angles, and the experimental results were found to be consistent with simulation results. Due to its advantages of high-efficiency absorption over a broad range of incidence angles, the proposed absorber can be used in energy harvesting and electromagnetic shielding.

本文提出了一种具有三重吸收峰的超薄柔性超材料吸收器（MA）。所提出的吸收器的设计方式使得三个吸收峰位于 8.5、13.5 和 17 GHz（X 和 Ku 频段），吸收率分别为 99.9%、99.5% 和 99.9%。所提出的结构仅0.4毫米厚，约为各波段吸收频率各自自由空间波长的1/88、1/55和1/44。由于其对称的几何形状，MA 也不敏感。此外，所提出的结构在 60° 入射角内表现出最小 86% 的吸收（TE 入射）。对于 TM 入射角，所提出的吸收体在高达 60° 入射角时表现出超过 99% 的吸收率。研究表面电流和电场分布以分析控制吸收的机制。进行参数分析以优化吸收。此外，MA 的性能在自由空间中通过在柔性电介质上制造的 20 × 30 单元电池进行测试的样品进行了实验证明。在法向入射下，所制造的MA在所有偏振角度的每个吸收峰处都表现出近乎完美的吸收，并且实验结果与模拟结果一致。由于其在较宽的入射角范围内高效吸收的优点，所提出的吸收器可用于能量收集和电磁屏蔽。