A high-efficient tunable liquid metal-based electromagnetic absorbing metamaterial

Considerable attentions have been attracted to the implement of electromagnetic (EM) absorbing metamaterial in the past decade. Most of EM absorbing metamaterials focused on the design methods of increasing the broadband performance. However, high-efficient tunable EM absorbing metamaterials still remain a significant challenge. In this work, a 3D-printed high-efficient tunable liquid metal-based EM absorbing metamaterial was designed and demonstrated successfully. A square cavity with four gradient-depth T-shaped microchannels structure was considered as the unit cell of absorbing metamaterial. By taking advantage of the extraordinary fluidity and high conductivity of liquid metal, the high-efficient tunable capability with nearly perfect absorbance from 4.42 to 10.45 GHz and the absorbance over 95% from 3.13 to 4.44 GHz were obtained numerically and experimentally. The simulated results of absorbance agreed well with the measured ones. The designed absorbing metamaterial provides an outstanding way to achieve continuously tunable work frequency in a broadband frequency range, promoting potential application in multi-frequency microwave filters and electromagnetic shielding fields.