Research of slow-wave circuit CAD of gain and phase matched operation helical TWTs

Designing an octave bandwidth helical traveling wave tube for phase and gain matched operation in the EHF region presents many obstacles, including the dimensional controls which must be imposed in the design. In this paper, a code, which is based on the sheath model is used to analyze the effect on dispersion and impedance of several helical slow-wave circuit parameter variations, including thickness and relative dielectric constant of the support rods, pitch width, height of the metal vane and helix average radius. The dispersion and impedance are compared for each set of variations. These computational techniques are readily applicable to other TWTs.