Uniform Circular Array System for Generating Orbital Angular Momentum Beams

In this paper, a planar double-layer PCB uniform circular array (UCA) system is designed to generate orbital angular momentum (OAM) beams. The UCA system consists of planar directional antenna elements on the top layer, a uniform power divider, and a phase shifter network to produce the required excitation phases on the bottom layer. Such a UCA system with four linearly polarized rectangular patch elements resonating at 17.8 GHz and an impedance-matched phase shifter network capable of generating the mode -1 OAM beam is designed and simulated. The array system is fabricated on a double-sided PCB with the array in the top layer and the phase shifter network in the bottom layer. The simulated and the experimental OAM beam results agree with those of a UCA with individual port excitations. The proposed modular array system design can incorporate greater antenna elements to generate higher OAM modes.