Analysis of Alternate Dielectric and Metal Vane Loaded Circular Waveguide for a Wideband Gyro-TWT

A composite circular waveguide interaction structure of a gyro-traveling-wave tube (gyro-TWT) consisting of azimuthally periodic alternate dielectric and metal vanes projecting radially inward from the waveguide wall was analyzed by the field matching technique considering the effect of azimuthal harmonics. The dispersion relation of the waveguide excited in the TE mode obtained by the analysis was validated against the simulation within 5% and then used to find the optimum structure parameters for wideband coalescence between the beam and the waveguide mode dispersion characteristics for wideband device performance. The dispersion data fed into the gyro-TWT gain formula established the superiority of the proposed composite dielectric- and metal-vane-loaded waveguide in providing a wide bandwidth of the device without much sacrifice of its gain while requiring a lower beam voltage and magnetic field, over a waveguide loaded by a dielectric lining alone or by metal vanes alone.