Time-Efficient Multiplex Orbital Angular Momentum Beam Synthesis With Arbitrary-Shaped Array Using Multipole Moment Expansion

Despite the significant interest in pattern synthesis over the decades, the beam synthesis of orbital angular momentum (OAM) has received relatively little attention. In this article, we present a time-efficient method for OAM beam synthesis based on multipole moment expansion (MME). The approach introduces the multipole moment term as a transforming level, which separates the excitation coefficients and radiation pattern. We evaluate the performance of our proposed method through several examples and demonstrate its high capability to synthesize multiplex OAM beams with arbitrary-shaped arrays, ensuring reasonable accuracy. The theoretical analysis shows a significant improvement in computational efficiency and a great reduction in computational complexity compared to conventional synthesis methods. Finally, we design, fabricate, and measure a double-ring concentric circular patch antenna array using our proposed method, and the measured results confirm the validity of our approach. The work provides a valuable contribution to the field of OAM beam synthesis and offers a promising avenue for future research.