Metasurfaces exhibit promising capacities in the manipulation of electromagnetic (EM) waves, as to diverse dimensions like amplitude, phase, and polarization. Despite many methods have been used to improve regulatory capabilities of EM waves, the efficiency and working bandwidth has yet to be developed. In this paper, an ultra-wideband and high-efficiency reflective polarization converter metasurface (PCM) is proposed. Both theoretical analysis and simulation results show that the polarization conversion ratio (PCR) is above 89% in the ultra-wideband from 2.28 THz to 6.75 THz, and the relative bandwidth reaches 99%. Moreover, the multi-bit digital coding metasurface elements are designed by using Pancharatnam–Berry (PB) phase principle. The coding metasurface arrays are designed by using different coding sequences, which can be used to realize the free adjustment of scattering angle of the reflected EM waves. In addition, the radar cross section (RCS) reduction performances of the designed metasurface array antennas based on different coding elements are studied. The results present that it can significantly reduce the RCS by −20 dB over a wide frequency range from 2.1 THz to 6.9 THz. The proposed metasurface has great application potential in manipulation of terahertz wave and contributes to RCS reduction.

超表面在操纵电磁 (EM) 波方面表现出有前途的能力，包括幅度、相位和极化等不同维度。尽管已经使用了许多方法来提高电磁波的调节能力，但效率和工作带宽还有待开发。在本文中，提出了一种超宽带和高效反射偏振转换器超表面（PCM）。理论分析和仿真结果均表明，在2.28 THz至6.75 THz的超宽带范围内偏振转换比(PCR)均在89%以上，相对带宽达到99%。此外，多位数字编码超表面元件是利用 Pancharatnam-Berry (PB) 相位原理设计的。编码超表面阵列是通过使用不同的编码序列设计的，可实现反射电磁波散射角的自由调节。此外，研究了基于不同编码元件设计的超表面阵列天线的雷达截面（RCS）降低性能。结果表明，它可以在 2.1 THz 到 6.9 THz 的宽频率范围内将 RCS 显着降低 -20 dB。所提出的超表面在操纵太赫兹波方面具有巨大的应用潜力，并有助于减少 RCS。