LAUSR

In this paper, metasurfaces are designed, fabricated and experimentally demonstrated to transmit and receive a mixed-mode orbital angular momentum (OAM) vortex wave. Firstly, the theoretical formula of compensated phase-shift distribution is deduced and used to design the metasurface to produce the mixed-state vortex wave. Then, simulations and near-field scanning experiments are performed to verify that mixed-state vortex waves can be generated and received by using metasurfaces. The receiving experiments for mixed-mode OAM beam are conducted in the near-field zone, covered frequency band from 4.5 GHz to 7.0 GHz. In transceiving experiments, the TX is the proposed reflective metasurface generating the mixed-state OAM wave (P = 2, l1 = 1, l2 = 2), which is composed of square loop elements. The RX is an OAM receiving metasurface composed by crossed dipole elements, which can receive OAM mode l = 1 in vertical polarization but OAM mode l = 2 in horizontal polarization. Experimental results show that mixed-state vortex waves can be detected, received and separated by pure OAM-mode transmitting and receiving reciprocal metasurfaces. The proposed method paves an effective way to generate and detect the OAM vortex wave of mixed modes for microwave wireless communication and detection applications.