Synthesis of orbital angular momentum antennas for target localization

The exploitation of Orbital Angular Momentum (OAM) is proposed to design circular-support continuous aperture distributions and concentric-ring arrays for target-localization applications. The proposed approach allows generating a single isolated null of the field in the target direction, which is of interest with respect to common techniques leading to a line (or perpendicular lines) of power-pattern zeroes in the spectral plane. In the presented design procedure, the optimal continuous aperture source is first identified by resorting to the most suitable OAM vortex and effective tools such as the Singular Value Decomposition of the involved operator and a smart Convex Programming optimization. Then, by exploiting fast deterministic algorithms, this continuous source is discretized into circular-ring arrays emulating it at best. Relevant applications including equispaced arrays, sum-difference reconfigurable arrays, and isophoric sparse arrays are presented. The proposed approach is also compared with the state-of-the-art techniques and assessed through full-wave electromagnetic simulations.