High power bend mode converter in overmoded waveguide for gyroklystron

The output mode of gyroklystron TE₀₁ and TE₀₂ are very inconvenient for direct use, so it must be taken a mode conversion, especially high power mode conversion. And its mode converter adopt mostly the following sequence: 1. TE_on (gyrotron) -TE₀₁-TE₁₁-HE₁₁ (antenna) 2. TE_on (gyrotron) -TE₀₁-TM₁₁-HE₁₁ (antenna) The first sequence has been employed here, adopting perturbation of axis curved, and arriving at an efficient circular waveguide converter with conversion efficiency reaching 98% and bandwidth exceeding 5%, while its overlength(881.6mm) confines its practice to a limited field with inconvenient machining. Thus the second sequence is chosen to for better usage, with TM₁₁ as the intermediate polarized mode, HE₁₁ the latter one, to radiate outside, during the process of which TE₀₁-TM₁₁ conversion is the most important. The same phase velocity of TE₀₁ and TM₁₁ made a proper selection of a part of the single-curvature circular waveguide fit the realization of their conversion well.