Lens antenna for 3D steering of an OAM-synthesized beam

In this paper we present a lens antenna for 3D beam steering at microwave frequencies. Over the azimuth, 360 degrees beam steering is realized through exploiting the orbital angular momentum (OAM) property of the electromagnetic wave components of the beam. A beam pointing toward a certain direction in the azimuth is optimized by an appropriate superposition of waves carrying different OAM orders; the beam direction is manipulated by the relative phase shifts between waves. The elevation of the beam is separately controlled by coupling the OAM wave generators to a Maxwell fish-eye lens. The proposed antenna operates with high directivity, narrow beamwidth, and low side lobe levels over a wide spatial steering range. Among the results, a stable beam of about 10.8 dBi main lobe gain, 3 dB beamwidth of 17.4 degrees, and -4.7 dB sidelobe level is synthesized over wide azimuthal and elevation ranges. The effects of the characteristics of the lens on beam steering are analyzed in detail. The method has been demonstrated to work effectively by numerical simulations.