Transmitarray Antenna for Generating Multiple OAM Modes

This paper introduces a novel transmitarray antenna for generating two coaxially propagating orbital angular momentum (OAM) modes with same polarization at 60 GHz. Each OAM mode corresponds to an independent communication channel. The designed transmitarray can compensate for the spatial phase delays from the two feed sources at different positions and generate vortex waves with two different OAM numbers simultaneously. Measured results of the transmitarray antenna prototype show that it can successfully generate two independent OAM modes with mode number l = -1 and +1 simultaneously. The introduced transmitarray antenna can find promising applications in millimeter-wave (mmW) high-speed OAM-based mode-division-multiplexing wireless communications.