Optimized Design Method for Multimodal Low-coupling Orbital Angular Momentum Arrays for Radar Detection Applications

Vortex electromagnetic waves carrying Orbital Angular Momentum (OAM) can meet the requirements of modern radar detection systems for high resolution and precision. However, existing OAM beam generation methods suffer from limitations, such as insufficient multimodal purity and strong mutual coupling between array elements. To overcome these challenges, this paper designs and optimizes pyramidal horn antenna elements based on a uniform concentric circular array, thereby establishing a multimodal OAM array model. A double-layer metal ground plane structure is introduced to effectively suppress mutual coupling between array elements. Furthermore, the array configuration is optimized to generate high-purity, co-directional multimodal OAM beams. On this basis, a genetic algorithm is used to further optimize the design for generating multimodal OAM beams with low sidelobes. Full-wave simulations show that the optimized array achieves an active reflection coefficient below −10 dB, indicating substantially suppression of the mutual coupling between elements. The proposed array exhibits a stable structure suitable for engineering applications and supports the generation of 14 co-directional OAM beams with modal purity exceeding 0.92 and sidelobes below −13 dB. Finally, the performance of the designed array is validated through fabrication, testing, and super-resolution imaging experiments.