Millimeter-Wave Orbital Angular Momentum: Generation, Detection, and Applications: A Review on Millimeter Wave Orbital Angular Momentum Antennas

With the increasing popularity of fifth-generation (5G) applications, the demand for channel capacity and spectral efficiency for wireless applications has grown exponentially. To meet the increasing data transmission demand, multiplexing techniques based on amplitude, frequency, and polarization are generally used to improve the information transmission [1]. However, such methods are no longer adequate for high-speed and complex signal transmission. As a new wireless communication technology, orbital angular momentum (OAM) technology can effectively increase the system capacity and improve spectrum utilization. A new direction for existing wireless communication multiplexing technology is provided [2].