Bragg coupling in corrugated circular waveguides

Circular waveguides with nonperiodical corrugation of wall and longitudinally gyrotropic filling are considered. The Krylov-Bogoliubov-Mitropolsky asymptotic method is used for solving boundary-value problem describing electromagnetic wave propagation in the close waveguiding structure. Mutual transformations of a wave modes propagating in such waveguides are investigated. Analytical solutions for some coupling coefficients are obtained. A variation of polarization parameters along longitudinal coordinate is analyzed. An influence of combination of a helical corrugation and longitudinal gyrotropy for mode and polarization transformation is investigated.