Propagation of electromagnetic waves guided by perfectly conducting model of a tape helix supported by dielectric rods

Abstract

The homogeneous boundary value problem existing in the electromagnetic wave propagation in a dielectric‐loaded perfectly conducting tape helix with infinitesimal tape thickness is investigated in this study. The ill‐posed boundary value problem is regularised using the mollification method. The homogeneous boundary value problem is solved for the dielectric loaded perfectly conducting tape helix taking into account the exact boundary conditions for the perfectly conducting dielectric loaded tape helix. The solved approximate dispersion equation takes the form of the solvability condition for an infinite system of linear homogeneous equations namely, the determinant of the infinite order coefficient matrix is zero. For the numerical computation of the dispersion equation, all the entries of the symmetrically truncated version of the coefficient matrix are estimated by summing an adequate number of the rapidly converging series for them. The tape‐current distribution is estimated from the null‐space vector of the truncated coefficient matrix corresponding to a specified root of the dispersion equation. The numerical results suggest that the propagation characteristic computed by the anisotropically conducting model (that neglects the component of the tape‐current density perpendicular to the winding direction) is only an abstinent approximation to consider for moderately wide tapes.

Dispersion Analysis of a Planar Rectangular Tape Helix Slow Wave Structures Supported by Dielectric Rods

“…Cold test analysis of unsupported tape-helix cylindrical TWTs using both field [1] and equivalent circuit [2] analysis approaches has been well established. Practically relevant cylindrical tape helices supported by dielectric rods [3] and corrugated dielectric support rods [4][5][6] have also been reported. Most reported tape-helix SWS models account for the anisotropic conductivity [7] of the tape rather than the perfectly conducting tape model [8,9] because it is well known that the contribution of the perpendicular component of the * Corresponding author: Naveen Babu (naveen.babu@snu.edu.in).…”