Analysis and design of CP Bessel beam launchers

In this paper the focusing capability of a radiating aperture implementing an inward traveling wave current distribution directed along a fixed unit vector is investigated. In particular, it is shown that such a current distribution generates a field profile with its transverse component (with respect to the normal of the radiating aperture) taking the form of a zero-th order Bessel profile. As a practical implementation of the theoretical analysis, a circular-polarized (CP) Bessel beam launcher, made by a radial parallel-plate waveguide loaded with several slot pairs and arranged on a spiral pattern, is designed and optimized. The designed launcher performance agrees with the theoretical model and exhibits an excellent polarization purity.