Conversion of a conical wave with circular polarization into a vortex cylindrically polarized beam in a metal waveguide

In this paper, we have developed a mathematical base for describing the propagation of waves in a metal waveguide in a cylindrical coordinate system. The transformation of a conical wave with circular polarization into a cylindrically polarized vortex beam is shown on the basis of the expansion of the field in vector cylindrical modes. The results of modeling, based on the expansion in plane waves, qualitatively agree with theoretical calculations.