Beam steering of vortex waves by a phased array based on the field equivalence principle

A further ability can be added to an existing phased array (PA) to include generation and steering of noncollimated or collimated electromagnetic (EM) vortex waves (VW). The concept is based on the EM field equivalence principle. The near field of VW's generated by a uniform circular array (UCA) is calculated on a tilted planar finite size reference aperture (RAP) which intercepts all the VW modes. Using the Love equivalence principle and the fields of UCA on the RAP, the VW's are calculated in the far field. RAP is divided into small rectangular subapertures (SAP), simulating the elements of a PA. The UCA-fields on each SAP, for a given RAP's tilt angle (steering angle) are calculated. These fields are to be generated by rightly polarized PA's antenna elements fed by the associated transmit-receive modules. The method is also applied to VW's tightly collimated by a paraboloidal reflector. Numerical simulations obtained verified this concept.