Demonstration of Mode-Tunable Vortex Wave Radiation from Pseudo-Traveling Wave Ring Resonators Using Nonreciprocal Metamaterials

In this paper, vortex wave radiation from pseudotraveling-wave ring resonators is demonstrated for the purpose of generation and tunable characteristics of orbital angular momentum (OAM) modes. The resonator is composed of nonreciprocal composite right/left handed transmission line on a normally magnetized ferrite ring. The numerical simulation and experimental results clearly show generation of multiple OAM modes with l = ±1 and ±2, and tunable mode selection by changing the applied dc magnetic field.