Noncylindrical Helix Waveguide

Small uniform deformations of the cross section of helix waveguide perturb the circular electric waves slightly. From these perturbations the added circular electric wave loss is found in a uniformly deformed helix waveguide. For a nonuniformly deformed helix waveguide Maxwell's equations are converted into generalized telegraphist's equations. By an approximate solution for small deformations, mode conversion and circular electric wave loss are found. Random imperfections with small correlation distance cause an average circular electric wave loss that is nearly independent of the wall impedance which the helix jacket presents to the waveguide interior. It is therefore nearly the same as in metallic waveguide. Near 50 kmc, the rms value of elliptical diameter differences should not be more than 0.0015 inch in order that on the average not more than 10 per cent of TE01loss in a perfect 2-inch inside diameter copper pipe is added to the TE01loss in a helix waveguide of the same inside diameter.