A Broadband Electronically Mode-Reconfigurable Orbital Angular Momentum Metasurface Antenna

In this letter, a 2 × 2 low-profile broadband triple-mode orbital angular momentum (OAM) array antenna is presented, which can be dynamically controlled with electrostatic method. The antenna element consists of a 4 × 4 metasurface array, a 90° phase-shifting reconfigurable feed network (RFN), and a square driven patch with two switchable feeding ports (SWPs). With the computer-assisted micro-controller unit, the p-i-n diodes direct current (dc) bias voltage on the RFN, and SWPs, the OAM modes can then be dynamically switched between l = +1, l = -1, and l = 0. The OAM beams of mode l = ±1 and mode l = 0 have been generated in the broad frequency with the impedance band of 4.9-6.5 GHz and 5.0-6.3 GHz, respectively. The experimentally measured peak gains of the triple-mode are 11.17, 11.05, and 15.19 dBi, respectively. Both the simulation and experiment demonstrate that the proposed antenna exhibits several advantages, such as mode-reconfigurable ability, broad frequency band, high directivity, and good helical phase front of the OAM waves.