DOUBLE VALUED PHASE CONSTANTS IN GYROTROPIC WAVE-GUIDES

Double valued phase constants for one direction of applied magnetic field in gyrotropic waveguides commonly occur in the vicinity of a degeneracy between hybrid modes at cut-off. A study of the circularly symmetric TM modes in azimuthally magnetised, plasma filled, coaxial waveguides, indicates that such a degeneracy is not a prerequisite condition for double roots. Cut-off curves are presented for the first two such modes together with a study of the behaviour of the transverse wavenumber for the dominant mode.