Pattern synthesis of the multimode orbital angular momentum beams based on the fruit fly optimization algorithm.

The multimode orbital angular momentum (OAM) radio waves can be used to multiplex multiple transmission channels to increase the capacity of communication system without adding additional bandwidth. However, the divergence of the OAM beams and beam inconsistency escalate by increasing OAM mode number. Moreover, the worse sidelobe level (SLL) always appears along with a better convergent beam. In this article, the fruit fly optimization algorithm (FOA) is proposed to suppress the SLL in multimode OAM scenario. Based on the concentric circular array antenna (CCAA), the feeding amplitudes and the radii of the array are synthesized simultaneously to realize less than −30 dB SLL of the multimode OAM patterns. When the main lobes with different OAM modes steered to a uniform azimuth of θ = 0°, the SLLs of these OAM modes are also suppressed to less than −21 dB. The advantages of FOA used in the OAM pattern synthesis are verified by comparing it with the genetic algorithm (GA). The FOA‐based synthesis has a simpler implementation flow diagram which reduces the time of synthesis to 39.5% of GA. [ABSTRACT FROM AUTHOR]