A Compact Dual-band Dual-Sense Circularly Polarized OAM Antenna

With the rapid development of fifth-generation communication technologies, demands for a high channel capacity are increasing to enhance spectrum utilization. We propose a compact multi-mode orbital-angular-momentum (OAM) antenna array consisting of four dual-band dual-sense circularly polarized pentagon patch elements with U-shaped slots. The sequentially rotated array could generate two OAM beams simultaneously at dual frequency for high-speed communications. Simulation results indicate return-loss bandwidths of 2.62 GHz (8.90-11.53 GHz) at lower frequencies and 0.97 GHz (13.33-14.30 GHz) at higher frequencies. Furthermore, two OAM beams of modes 1 and -1 work at 9.2 GHz and 13.7 GHz, respectively, while axial ratio bandwidths are 0.17 GHz and 0.22 GHz. The antenna exhibits good impedance matching, with isolation levels over 18 dB across the operating frequency bands.