A 3-D-Printed Ultrawideband and Ultralow-Scattering Water-Based Metasurface

In this communication, a water-based metasurface is proposed using hybrid mechanisms of absorption and phase cancellation for ultrawideband and ultralow scattering. Pure water as the lossy material is utilized in our work due to its high-dielectric loss and easy accessibility. In addition, 16 water-based unit cells with different parameters are selected according to optimized multielement phase cancellation (OMEPC). The best backward scattering reduction can thus be acquired since the combination of different unit cells can achieve the desired phase difference condition in ultrawideband. The 3-D radar cross-sectional (RCS) patterns and the ratio of energy dissipation demonstrate that the ultrawideband and ultralow backward scattering of the proposed design is due to the combined effect of absorption and diffusion. The simulated 10 dB (15 dB) RCS reduction bandwidth is from 2 to 100 GHz (9.7–100 GHz). The RCS reduction results can maintain stable under wide-angle incidence up to 60°. Finally, a prototype with
$4\times4$
arrays based on 3-D printing technology is fabricated and measured for demonstration. Each array is a subarray of 5
$\times5$
unit cells with the same parameters to facilitate processing. The measured results are in good agreement with the simulated ones.