Electromagnetic Wave Manipulations via Liquid-metal-based Coding Metamaterial System

For decades, metamaterials have been widely investigated for their excellent feature of fashioning the spatial electromagnetic (EM) waves. Moreover, to control the EM waves in a digitally discretized manner, the concepts of the digital coding metamaterial and programmable metamaterial were proposed in 2014. However, most time, the reconfigurable function of the coding metamaterials is realized by electricity through active elements, such as PIN diodes. Here, we introduce another driving manner, liquid-metal-based mechanical driving, to the coding metamaterial system. In general, liquid-metal-based coding metamaterials have two main distinguishing features: 1) they can implement reconfigurable states continuously owing to the fluidity; 2) they can get rid of the mechanical fatigue and damage due to the flexibility of liquid metal and its containers. In the paper, we begin by designing a liquid-metal-based meta-atom with the characteristics of broadband reconfiguration, multi-bit coding and wide-angle incidence. Then, the designed meta-atoms are spatially arranged to realize the applications of broadband beam-steering and broadband RCS reduction.