Beam steering using OAM waves generated by a concentric circular loop antenna array

Abstract

Orbital Angular Momentum (OAM) is an attractive feature of electromagnetic waves that gains great research attention in several areas in radio and optics. This paper describes a superposition of OAM waves of different orders for single/multi-beam steering in the transverse direction in communication and radar-sensing applications. A new design of the antenna is proposed. The main body of the antenna consists of a concentric circular loop antenna array that is excited by a traveling wave current. This design overcomes some of the limitations challenging the use of multi-orders OAM waves in beam steering, in particular the need for placing more than one OAM-order generator in the same plane. The proposed method overcomes this limitation as many loops of different sizes could be simply placed in one plane. The feeder of the antenna, on another hand, is designed using two loops with one being a parasitic element. This parasitic element-based design shows great enhancement to the bandwidth allowing the antenna to serve over a wide range of applications. Various OAM mode groupings using the superimposed OAM waves are demonstrated here via theoretical calculations, and beamforming is validated with full-wave numerical simulations.