A compact three-ring nested circularly polarized patch antenna for three-mode OAMs generation

In this paper, a compact three-ring nested patch antenna is proposed for generating multiple orbital angular momentums (OAMs) at a single frequency. This antenna is composed of a square dielectric substrate, a three-ring nested patch printed on the top layer of the substrate, and three coaxial lines. Two symmetry rectangle patches are connected to every single ring patch to ensure the generation condition of the circularly polarized OAM waves. By changing the size of ring patches and the angle between rectangle patches and the feeding point, the OAM modes of the generated wave are adjustable. After that, simulation results indicate the compact three-ring nested patch antenna can generate vortex waves with OAM modes 1, 3, and 5 at 2.5 GHz efficiently. Due to the multiple modes simultaneously at a single frequency, the antenna is potential for wireless communication.