Gain and Bandwidth Analysis of a Vane-Loaded Gyro-TWT

Abstract

Theoretical investigation of the peak-gain and 3-dB bandwidth of the vane-loaded gyro-traveling wave tube (gyro-TWT) amplifier in the small-orbit TE 01 waveguide mode configuration at 35 GHz has been presented. The vane-loaded gyro-TWT enjoys higher gain and bandwidth compared to that of the smooth-wall device. In the analysis, the azimuthal harmonic effects generated due to the angular periodicity of vanes in the wedge-shaped metal vane-loaded cylindrical waveguide interaction structure have been taken into account in the cold (beam-absent) dispersion relation only.

Analytical Study of the Interaction Structure of Vane-Loaded Gyro-Traveling Wave Tube Amplifier

“…The effects of the vane parameters [67] have thus been encapsulated only in the waveguide-mode axial phase propagation constant and cutoff wavenumber, subsequently plugged into the gain equation of a gyro-TWT in an otherwise smooth cylindrical waveguide which is known as approximate approach as shown in Fig. 4.…”

Te and Tm Modes of a Vane-Loaded Circular Cylindrical Waveguide for Gyro-TWT Applications

“…In a paper [5] published in 2002, Singh et al have used the dispersion relations of [1] for finding the dispersion characteristics of 'TE 01 ' and 'TE 21 ' modes for a typical set of vane-parameter values. In the papers by Singh et al [6][7][8][9][10], various methods of analyzing/improving the frequency-response characteristics of gyro-TWT amplifiers have been proposed based again on the results from [1]. The papers [11] by Singh and Basu and [12] by Singh were devoted to analytical studies of the interaction structure of vane-loaded gyro-TWT amplifiers starting again from the cold-wave dispersion relations appearing in [1].…”

“…Notwithstanding the impressive list of applications of the vaneloaded structure cited in the previous paragraph, the 'derivation' of the dispersion equations for this structure attempted in [1] is seriously flawed rendering the results and conclusions of [2][3][4][5][6][7][8][9][10][11][12] to be of questionable validity for the following reason: The azimuthal dependence of the assumed form of the solution for the field components in the annular region containing the vanes does not permit the boundary condition on the radial component of the electric field, viz., the radial electric field component should vanish on the lateral boundaries (located on the radial planes passing through the waveguide axis) of the perfectly conducting vanes, to be satisfied; more fundamentally the assumed form of solution is not capable of ensuring a null electromagnetic field everywhere inside the vane region.…”