Multiple Orbital Angular Momentum Circular Polarization Vortex Beam Design with Equal Divergence Angle

Orbital angular momentum (OAM) beams with different modes usually perform different divergence angles, leading to higher complexity of signal reception. To address this issue, this paper proposes a multiple rings concentric uniform alternating circular array (CUACA) design method, which adopts the form of group alternating feeding. Moreover, by adjusting the radii of the different single rings uniform circular array (UCA) the inner and outer rings of the array generate ± 1 and ± 2 OAM modes vortex beams with equal divergence angle. To validate the design, a C-band antenna prototype with multiple OAM modes is simulated, fabricated, and measured. The simulation results and measurement results show that the multiple OAM modes vortex beams with equal divergence angle can be well realized.