Generation of One-Bit Vector Orbital Angular Momentum Waves without Central Null based on Polarization Conversion Metasurface

One-bit vector orbital angular momentum (OAM) waves without central null are presented and realized. The vector OAM waves simultaneously carry vortex in both phase and polarization distribution in space, leading to the possibility of eliminating the central null. By combining a transmissive polarization conversion metasurface with an ordinary patch antenna, the first-order vector OAM waves are generated at 10 GHz. Simulation and measurement results show that the vector OAM waves eliminate the central null of conventional OAM waves. The measured gain at the central of vector OAM, i.e., at the propagation direction, is 3.9 dBi, which demonstrates that this vector OAM along with polarization conversion metasurfaces is potential for middle- and long-range wireless communication.