The periodic boundary condition in the three-dimensional (3-D) electromagnetic computer code CST MWS is used to the computational simulation for high-frequency characteristics of helical slow-wave circuit.Validated by the analytical method of tape helix model and the experimental data

the agreement is excellent.The computer code CST MWS and tape helix model are also used in this analysis to determine the effect on dispersion and on-axis interaction impedance of the wedge support rod and T-shaped support rod geometry parameter variations.The results show that the phase velocity and interaction impedance will decrease across the bandwidth while the angle of the wedge support rod and the width of T-shape support rod’s narrow end increase

and increase while the height of T-shaped support rod’s narrow part is longer.