A 1-bit Reflective Metasurface for Generating OAM Waves Based on Linear Polarizer

This paper presents a novel 1-bit reflective metasurface to generate orbital angular momentum (OAM) waves in radio frequency domain. The metasurface unit cell is based on a wideband linear polarizer, which consists of a single-layer substrate with top polarization rotating patch (PRP) and bottom metallic ground. The proposed unit cell and its mirror image can maintain a stable 180° phase difference over a wide bandwidth of 18-36 GHz. Thus, 1-bit phase quantization is obtained by using this property. Based on the linear polarizer, a 1-bit reflectarray for generating +1 mode OAM waves is designed and simulated. The simulated results show that +1 mode OAM vortex electromagnetic waves are successfully generated and a small divergence angle of +/- 4° is obtained, with a high gain of 19.2 dBi at 27 GHz.