Helical Circular Array Configurations for Generation of Orbital Angular Momentum Beams

• Published in: IEEE antennas and wireless propagation letters Vol. 22; no. 5; pp. 1139 - 1143
• Main Authors: Yesilyurt, Ugur, Polat, Hilal Koc
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.05.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Angular momentum; Arrays; Azimuth; Configurations; Electromagnetic radiation; Electromagnetic scattering; Electron beams; Helical circular microstrip patch array; Linear phase; Microstrip; Microstrip antenna arrays; Optical vortices; orbital angular momentum (OAM); Phased arrays; Spirals; vortex electromagnetic wave; Wave fronts
• ISSN: 1536-1225; 1548-5757
• DOI: 10.1109/LAWP.2023.3234591

The vortex electromagnetic waves carrying the orbital angular momentum (OAM) are an increasing subject of study, and the design of a system capable of generating such waves is also of crucial importance. In this letter, a helical circular array (HCA) has been proposed to generate OAM radio beams. The proposed HCA has a more straightforward and more feasible scheme when compared to uniform circular arrays that require additional phase-shifting devices to form interelement phases. The heights of the proposed HCA elements along the <inline-formula><tex-math notation="LaTeX">z</tex-math></inline-formula>-axis are exploited to generate the different OAM modes. For the high-order OAM modes, the height of the HCA is made more compact with the help of the proposed helical circular subarray (HCSA) configurations with spiral phase positions providing a linear phase delay with the azimuth angle. In addition, at high mode values, the HCSA structure creates a smoother OAM vortex beam than HCA. The full-wave simulation results show that the proposed HCA scheme can be used to generate vortex electromagnetic waves with a spiral phase wavefront structure.