Quadra-OAM-Mode SIW Slot Antenna Using Circularly Traveling Wave Resonator Structure

This paper presents an SIW slot antenna using two circular ring resonators with traveling wave inside radiating beams with orbital angular momentum (OAM) mode numbers ±3 and ±4. Two separated SIW circular resonators with phase variation of 6π and 8π along with two 90° hybrid couplers are introduced to obtain four OAM mode radiation. Analytical formulas are demonstrated to derivate the feeding port position and other parameters of the antenna, whose feasibility is verified in simulations using HFSS.