Orbital Angular Momentum (OAM) Mode-Reconfigurable Discrete Dielectric Lens Operating at 300 GHz

A novel three-dimensional printed discrete dielectric lens (DDL) antenna with orbital angular momentum (OAM) mode reconfigurability operating at 300 GHz is proposed in this article. The antenna consists of a stationary lower DDL and an upper in-plane rotatable DDL, fed by a stationary pyramidal horn. The DDL pair can transform the quasi-Gaussian beam from the feed source into vortex waves, and its OAM mode number, l, can be dynamically reconfigured among 0, +/- 1, and +/- 2 by a simple mechanical in-plane rotation of the upper DDL panel with specific angles relative to the stationary lower one. For the DDL design, the height of each dielectric post pixel element is tuned to realize the required transmission phase. The OAM mode-reconfigurability of the proposed terahertz (THz) antenna was validated by both simulations and measurements. The simulated OAM mode purity bandwidth of the design DDL antenna are 40%, 31.3%, and 25.8% for the OAM mode l = 0, +1, and +2, respectively. In addition, the THz line-of-sight link experiments show that acceptable mode isolations among different OAM channels can be achieved by the THz DDL antenna, validating its application for OAM mode diversity.