Multi-mode Orbital Angular Momentum (OAM) Antenna Array

Due to the demand for improving the spectral efficiency in wireless communication, Orbital Angular Momentum (OAM) has aroused widespread attention due to its potential to provide new capacity in the highly congested spectrum. This paper describes the design of 8 elements Uniform Circular Antenna Array (UCA) of rectangular patch working at 5 GHz. All the antennas are placed equidistantly in a circular manner with a radius of $0.6\lambda_{0}$. By providing appropriate phase shifts between adjacent elements, the UCA can generate multiple OAM beams such as $l= \pm 1,\ \pm 2,\ \pm 3$. All these modes are mutually orthogonal to each other and thus can be multiplexed together on the same frequency, i.e., 5GHz. The impedance bandwidth of 200 MHz is obtained by the simulation. The maximum gain of 11.9 dBi is obtained at first order OAM. However, the gain of 9.3 dBi and 8.7 dBi are obtained at second and third order OAM beams, respectively. The proposed antenna array can be used in Wi-Fi applications. However, antennas generating OAM waves can also be used for particle manipulation and target imaging.