A Planar OAM Filtenna•Based on a Compact Integration of the Incomplete UCA and the SSPPs

This paper proposes a planar orbital angular momentum (OAM) filtering antenna, which generates right-handed circularly polarized waves (RHCP) through leaky-wave radiation based on periodically modulated spoof surface plasmon polaritons (SSPPs). The filtering functionality is integrated without increasing the size of the antenna. The SSPP waveguide is distributed in a spiral pattern, ensuring the patches maintain equal distances from the circle's center. A missing element forms an incomplete uniform circular array (UCA). An OAM mode of l-1 is generated for RHCP waves by sequentially rotating the patches. The simulation results show that the proposed antenna achieves a peak gain of 9.17 dBi and an impedance bandwidth of 3.87-5.8 GHz, capable of generating six right-handed circularly polarized OAM modes from l = -4 to l = +1.