Synthesis of Orbital Angular Momentum Antennas for Target Localization

• Published in: Radio science Vol. 58; no. 2
• Main Authors: Battaglia, Giada M., Isernia, Tommaso, Palmeri, Roberta, Morabito, Andrea F.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 01.02.2023
• Subjects: Algorithms; Angular momentum; antenna arrays; antennas; Apertures; Computational geometry; Convexity; Decomposition; Design; electromagnetic theory; Localization; Mathematical programming; Optimization; Power; Sidelobes; Singular value decomposition; Synthesis; wave propagation
• ISSN: 0048-6604; 1944-799X; 1944-799X
• DOI: 10.1029/2022RS007592

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. Plain Language Summary The addressed problem is the synthesis of power patterns for target localization. The present work provides an original and relevant contribution to the research community by introducing a new method to design circularly‐symmetric continuous aperture distributions as well as circular‐ring arrays able to maximize the localization accuracy while keeping under control both the beamwidth and the sidelobe level of the power pattern. By virtue of the powerful tools that are jointly exploited, which include the Orbital Angular Momentum beam modes, the Singular Value Decomposition of the corresponding operator, and a Convex Programming optimization of the problem's unknowns, the proposed approach results deeply different from those available in the literature and can overcome a number of intrinsic limitations of the latter. Hence, the achieved results are relevant and original from both the methodological and application points of view. With respect to the available solutions, the introduced paradigm will provide a number of advantages in terms of both application range and technological impact. Key Points Orbital Angular Momentum of radio waves can be used to improve precision pointing Low‐sidelobe vortex beams can be seen as difference patterns of monopulse radars Exploiting at best Convex Programming and Singular Value Decomposition allows outperforming classical synthesis techniques