A 90-degree Bent High-power TM₀₁-TE₁₁ Mode Converter in Highly Overmoded Circular Waveguide

This paper presents highly overmoded 90-degree bent high-power circular waveguide mode converter with high mode conversion efficiency. This converter, which directly incorporates a 90 -degree bend, offers a more compact structure than the separate design of a 90 -degree $T M_{01}$ bend and a $T M_{01}$-$T E_{11}$ mode converter. By employing the RK-4 (Fourth-order Runge-Kutta) method and an iterative algorithm for curvature adjustment along the central axis, coupling wave equations are effectively solved, resulting in a mode converter with a nonanalytic curve form. Notably, this converter achieves coupling efficiency of $\mathbf{9 9. 8 \%}$ between $T M_{01}$ and $T E_{11}$ modes. This $\mathbf{9 0}$ degree bent converter holds promise for applications in highpower systems.