Optimal Synthesis of Circular Ring Arrays for Targets Localization via Orbital Angular Momentum Vortex Beams

We propose a new way to use Orbital Angular Momentum (OAM) antennas for the synthesis of circular-ring arrays aimed at the localization of targets. Being able to generate a single null of the pattern in the spectral plane, the proposed solutions can achieve good localization performances as compared to the common techniques which lead to a whole line of zeroes in the spectral plane (or two perpendicular rows in case of 'delta square' patterns). The design procedure relies on two main steps: first, a Convex Programming (CP) optimization is performed in order to identify a continuous aperture source maximizing the localization performances through an optimal exploitation of the OAM modes and, then, a proper discretization of the continuous source into the sought circular-ring array is performed. Comparisons of radiation performances between the benchmark continuous aperture source and the corresponding designed array are given.