Dual-functional tunable coding metasurface based on saline water substrate

In this paper, a dual-functional tunable coding metasurface is presented at X band based on water substrate, which can realize two different functions of specific scattering pattern and absorption at two different frequency ranges. Besides, by changing the salinity of the saline water substrate, the absorption performance in high frequency can be tuned, while the scattering pattern in low frequency remains unchanged. A coding element is designed with small water cavity in it. Three coding sequences with different radiation patterns are designed to verify these functions, and one of them is fabricated and measured. Experimental results have good accordance with our simulations, which demonstrates our schemes. We believe this work can not only broaden our design manner of metasurfaces, but also have plenty potential applications in biological and medical detection domain.