Orbital angular momentum wave generation/detection based on planar multi‐slot‐spiral circularly polarized antenna

Orbital angular momentum (OAM) as vortex wave has potential application for dense communication. A multi‐slot antenna is proposed based on Archimedean spirals to generate/detect the OAM waves. The antenna equips three radiation slots in a disk‐manner to realize three different OAM modes simultaneously. A serial‐fed microstrip array is designed for circularly polarized (CP) radiation. The lengths of the slots and microstrip lines are chosen to radiate at 3.5 GHz with 20% fractional bandwidth. So, it can identify the receiving modes of vortex wave with this mechanism. A prominent spiral phase plane is observed for the generated OAM wave. In addition, the far‐field pattern presents a doughnut‐shape beam. The whole antenna is fabricated on a 13 cm printed circuit disk board. Both the experimental and simulation results show that the proposed antenna has valuable features to produce different vortex modes.