Analysis of a tapered disc-loaded waveguide for a wideband gyro-TWT

The solution of the dispersion relation of a disc-loaded circular waveguide for the propagation constant, obtained by the cold (beam-absent) field analysis, was fed back into the small-signal gain equation of a gyro-traveling wave tube (TWT) to assess the technique of tapering the structure cross section for widening the bandwidth of the device, a technique that is known to broadband the device in a smooth-wall waveguide, usually at the cost of the device gain. The disc-to-disc distance of a nontapered disc-loaded circular waveguide, reportedly the most effective structure parameter for widening the bandwidth of a gyro-TWT, becomes an insignificant parameter for tapering the structure for wide bandwidths of a gyro-TWT, while simultaneous tapering of the waveguide-wall and disc-hole radii led to wide bandwidths at reasonably large gains