An Ultrathin, Triple-Band Metamaterial Absorber with Wide-Incident-Angle Stability for Conformal Applications at X and Ku Frequency Band

Guangsheng Deng,Zhiping Yin,Xiangxiang Li,Hanxiao Sun,Kun Lv,Ying Li,Jun Yang,Baihong Chi

doi:10.1186/s11671-020-03448-0

Abstract

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.

Highlights

In recent years, metamaterials have received widespread concern due to their exotic properties, such as negative refractive index [1], perfect imaging [2], and inverse Doppler effects [3]
As part of the modified ring resonator (MRR) design, a square patch is added to each corner of the closed ring resonator, which increases the electrical length of the ring resonator and red-shifts the absorption frequency without increasing the size of the structure
An ultra-thin, flexible metamaterial absorber (MA) with three absorption peaks is presented in this paper

Summary

Introduction

Metamaterials have received widespread concern due to their exotic properties, such as negative refractive index [1], perfect imaging [2], and inverse Doppler effects [3]. Some simplified structural designs were presented to achieve multi-band absorption [41, 42]; the absorption at wide incident angle still needs to be improved. In merit of the unit cell design, the proposed triple-band MA exhibits high absorption even at wide angles of incidence.

Results

Conclusion