A Topological Charge Continuously Tunable Orbital Angular Momentum (OAM) Electromagnetic Wave Generation Method Based on Fixed-length Delay Line Mixing Circuit

Abstract

To overcome the drawback of complex structure and high cost attributed from the utilization of phase shifters to generate OAM in the conventional schemes, this paper proposes a new method for generating OAM based on a fixed delay line. By deriving the proposed system with fixed delay line theoretically, the relationship between the frequency of the input signal on the delay line and the topological charge of the OAM is obtained, and the topological charge of the generated OAM can be controlled by controlling the frequency. Furthermore, this paper proposes a vortex beam pointing control method based on phased array scanning, so as to realize the beam steering of OAM. It is then verified by using electromagnetic simulation, and the simulation results show that the proposed method is feasible. The proposed method not only has the advantages of simple structure and low cost, but also can generate OAM with continuously adjustable topological charge by controlling the frequency, which has the functions of topological charge reconstruction and dynamic adjustment.