The Effects of Amplitude and Phase Deviations in a Uniform Circular Array on Orbital Angular Momentum Beam

The projections for 6G suggest that the data rate will be more than 10 Gbps [1].The demand for increased data rates can be achieved using the spectrum more efficiently.A candidate to improve channel efficiency and reduce spectrum saturation is a new multiplexing method in the physical layer named orbital angular momentum (OAM).In radio communications, uniform circular antenna arrays (UCAA) can generate OAM-carrying beams.An OAM beam can be characterized by its helical wavefront and singularity point (beam null) at the beam center [2].However, due to fabrication tolerances and changes in material properties, there could be deviations in the phase and amplitude of the array element, which may lead to the degradation of the vortex structure of the beam.The electric field of a vortex beam can be expressed as a sum of contributions from N elements, each has a perturbed amplitude of and a perturbation phase offset , OAM phase term - , a phase factor of - for distance , and a polarization vector as in (1):