A Compact Helical OAM Antenna Based on Spoof Surface Plasmon Polaritons

The miniaturization of antennas by using Spoof Surface Plasma Polaritons (SSPPs) have been extensively studied due to their slow-wave characteristics. In this paper, we propose a compact helical orbital angular momentum (OAM) antenna array based on SSPPs which can radiate four different modes of OAM beams at the same frequency. This antenna array is composed of four helical antennas with different radius and these antennas are arranged in a specific way to achieve compact helical OAM antenna array structure while reducing coupling effects between helical antennas.