Chiral Mode Transformer for Hard Surface Waveguides

Abstract

Fields in axially balanced corrugated cylindrical waveguide, also called hard surface waveguide, which is filled with chiral medium are considered. The eigenfields inside the chiral hard surface waveguide are circularly polarised fields. In a nonchiral hard surface waveguide these eigenmodes are propagating with the same propagation factor. When the chiralty parameter of the medium is small, which can be achieved by putting a small number of chiral inclusions, i.e. helices, into the base material, the coupling of the eigenmodes is weak, and the effect of the chirality is seen as a change in polarisation of the propagating wave. This effect make it possible to make mode transformers and phase shifters. Also the chiral hard surface waveguide of a proper length can be used as a matching element between different kind of circular waveguides.