Study on the unusual features of OAM beams and vortex electromagnetic fields

The features of the vortex electromagnetic (EM) wave carrying orbital angular momentum (OAM) are studied, in this paper. The vortex fields for different polarizations are derived and the distribution of the electric field vector is presented. Subsequently, the propagation characteristics of vortex EM waves are analyzed. How the OAM mode varies with the propagation distance is depicted and the OAM-based radar range equation is defined accordingly. This theoretical analysis can be applied to wireless communications as well as target detection.