Modes of propagation in cylindrical waveguides with anisotropic walls

The modes of propagation in cylindrical waveguides with idealised anisotropic walls are investigated. The walls are assumed to be lossless and to be specified by longitudinal and circumferential surface reactances. It is shown that for every surface there is a second surface which supports modes with identical propagation characteristics and that these modes are duals of the first set with the E and H fields interchanged. In general, the propagating modes are either fast HEm hybrids or EHm hybrids; the latter may be fast, but are sometimes slow, surface waves. For some surfaces modified TMm-and TEm-modes are sufficient to satisfy the boundary conditions; when m = 0 these modes can propagate for any combination of the surface reactances. Mode charts for the case of unity azimuthal dependence (m = 1) are presented for a wide range of anisotropic surfaces to illustrate the types and characteristics of the modes which may propagate. Particular attention is given to balanced hybrid modes and the surfaces which will support them.