Transmission characteristics for wave-guide with helical corrugation

According to the general coupled-wave equations of wave-guide with helical corrugation, selecting the import-mode TE11, the coupled mode TE21 is gained. Based on the rules of mode coupling in helical wave-guide the determinate formula for coupling equation is obtained and analyzed. Using the iterative method can simplify the coupling equation. At the same time, analyzing the result can give the impact of transmission characteristics by the periods of helical wave-guide. The analytic formula of simplied coupling equation is employed to operate the rate of amplications in the work mode of helical wave-guide. The result indicates that the hybrid mode can be given within work frequencies, in which the main mode is TE21. The value of group velocity of hybrid mode is a constant number. And the b