Two-stage vane loading of gyro-TWTs for high gains and bandwidths

Abstract

In this theoretical paper, we exploit the high‐gain, through narrowband, potential of a vane‐loaded gyro‐TWT to suggest a two‐section vane‐loaded device configuration for large gains and bandwidths. We predict the lengths as well as the vane parameters and the background magnetic fields of the individual sections for the desired performance. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 210–213, 2000.

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

“…The Pierce-type gain equation may be derived from the dispersion relation (14) by an approach [59][60][61][62]70], which is similar to what is followed in obtaining the gain equation of a conventional TWT. For this purpose, the solution of (14) is sought around the cold propagation constant β of the waveguide, such that −jk z = −jβ+βCδ, with Cδ << 1, where C and δ are arbitrarily chosen dimensionless quantities.…”

“…Following the same method, one may derive, from the solution of the cubic equation (18), the gain equation of a gyro-TWT. The method, which is outlined in [59][60][61][62]70], leads to the following gain formula for a gyro-TWT in terms of the three solutions δ 1 , δ 2 and δ 3 , say, of (18), and x 1 , the real part of δ 1 , supposedly positive (corresponding to a growing wave solution):…”

“…For a gyro-TWT in a vane-loaded cylindrical waveguide, one may continue to use the gain Equation (20), however, with the proper interpretation of the interaction impedance K, the latter given by (19). If one uses the 'approximate' approach, that has been followed in the past to estimate the effect of loading a gyro-TWT by a dielectric, for instance in [13], one may continue to use the expression (19) for K, but take, for β in this expression, the corresponding value for the vane-loaded cylindrical waveguide instead of that for a smoothwall waveguide [59][60][61][62]. The value of β(= (k 2 0 − k 2 c ) 1/2 ) for a vaneloaded gyro-TWT in turn can be found from the solution of the cold dispersion relation of the structure (13).…”

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

“…A method of controlling the gain-frequency response by the beam and the magnetic-field parameters was proposed in [2] by the same authors based on the results of [1]. A two-stage vane-loading of gyro-TWT for high gains and bandwidths was proposed by Agarwal et al in [3] based again on the results of [1]. The dispersion relations 'derived' in [1] were modified by the same authors for tapered vanes in [4].…”

“…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.…”