OAM Waves with Fewer Redundant OAM Modes Generated by Two Circularly Polarized Antenna Arrays

Two circularly polarized antenna arrays, which reduce two redundant OAM modes, are proposed in this paper. One antenna array is composed of 8 right-handed circularly polarized (RHCP) antennas and radiates OAM mode l in x component, OAM mode l in y component and OAM mode (l+1) in z component. The other antenna array has 8 left-handed circularly polarized (LHCP) antennas and transmits OAM mode l in x component, OAM mode l in y component and OAM mode (l−1) in z component. The RHCP and LHCP antenna arrays produce OAM waves with fewer redundant OAM modes compared to the traditional single-direction antenna array. The feed excitations of the two circularly polarized antenna arrays have the same feeding system, which includes power dividers and phase shifters. The reflection coefficient parameters, radiation patterns and phase distributions are measured to display the radiated characteristics of the two proposed methods. Both the simulation and the experimental results demonstrate the effectiveness of the proposed methods.