Dispersion Characteristics From Simplified Dispersion Equation for Open Rectangular Planar Tape Helix

A rectangular open tape helix is analyzed for its dispersion characteristics that are numerically computed from the dispersion equation derived without any prior assumption of the current density distribution on the tape helix surface. The dispersion equation is a conjoint expression evaluated along the axial and transverse directions, obtained by applying the accurate boundary conditions to one-quarter of the structure. The dispersion characteristics are numerically computed for fundamental harmonic and a few higher-order modes after truncating an infinite number of simultaneous equations represented in the form of a determinantal representation:
$\vert \textbf {A}\vert = \textbf {0}$
. Comparing the computed characteristics to those of the theoretical sheath helix model reveals that they are significantly different. The dispersion characteristics are numerically computed, and the phase velocity and interaction impedance are simulated for various dimensional variations of the structure. Plotted phase velocity and interaction impedance curves reveal the potential usability of such devices as compact traveling wave tubes that can be miniaturized and printed to operate at much higher frequencies than conventional TWTs.