Generation of Multi-Mode OAM Waves Through Programmable 1-bit Digital Coding Metasurfaces

In order to exploit orbital angular momentum (OAM) transmitting data, multiple-mode OAM waves should be generated preferably by a fixed antenna. In this paper, a programmable 1-bit digital coding metasurface is presented for the generation of multi-mode converged OAM waves. The proposed reconfigurable element consists of a microstrip patch, a PIN diode, and a DC biasing circuit. Through electronically controlled the PIN diode ON and OFF, two states with a phase difference of 180°, i.e., "0" and "1" states, can be realized. By properly designing varying states of each element on the metasurface array, the OAM waves can be generated and dynamically reconfigured among l = 0 and l = 1 modes at 7.77GHz. As a consequence, it is potential in wireless communication applications.