Generation of OAM millimeter waves using traveling-wave circular slot antenna based on ring resonant cavity

A novel traveling-wave circular slot antenna based on ring resonant cavity is proposed to generate orbital angular momentum beams at millimeter-wave frequency. To converge its radiation, a ring focus parabolic reflector is cleverly designed. All the antenna components are fabricated by 3D-print technique and the electro-less copper plating surface treatment process. The near-field and the far-field are measured with a 3D platform with open-end waveguide and a rotate platform with a standard antenna. 60GHz millimeter waves carrying OMA states of l=±3 are obtained. The experimental results show that the antenna achieves proper performances with low reflection within the bandwidth and main lobe direction of less than 7°.