Chiral hard-surface waveguide mode transformer

Field propagation in cylindrical axially corrugated waveguide tilled with c hiral medium is considered in this paper. The depth of the corrugation is a quarter-wavelength, making a hard-surface (HS) boundary. The eigenfields i nside the chiral HS waveguide are circularly polarized. In a nonchiral HS w aveguide, these eigenmodes are propagating with the same propagation factor . However, for small chirality values, there exists weak coupling between t he eigenfields, which results in a change in polarization of the propagatin g field. This effect makes it possible to make mode-transformers and phase shifters. Also, the chiral HS waveguide of a proper Length can be used as a matching element between different kinds of circular waveguides.