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This letter proposes a thin transmitarray for generating wideband orbital angular momentum (OAM) vortex beams in the Ka-band. Our proposed element achieves a 360 ^ transmission phase within a 3 dB transmission magnitude, with a total thickness of 1. 8 mm (0. 18 ₀ at 30. 0 GHz). The symmetrical configuration of the unit cell enables its applicability in dual-polarized applications. We investigate the transmitarray performance across four OAM modes (l = +1, +2, +3, +4), specifically focusing on the +1 mode during fabrication and measurement. Our experimental findings validate the successful generation of a wideband vortex beam with OAM mode l = +1. The performance of the beam is observed over a broad frequency range from 27. 0 to 39. 0 GHz (about 40% OAM bandwidth). Moreover, the proposed structure exhibits a peak gain of 21. 9 dBi with a corresponding aperture efficiency of 12. 3%, while the overall mode purity exceeds 71%.
Ishfaq et al. (Thu,) studied this question.