A W-Band Rectangular Waveguide TE₁₀ to Circular Waveguide TE₀₂ Mode Converter

In this article, a broadband $W$ -band $\mathrm{TE}^{\square }_{10}$ – $\mathrm{TE}^{\bigcirc }_{02}$ mode converter is proposed and verified. To improve the output performance of the $\mathrm{TE}^{\square }_{10}$ – $\mathrm{TE}^{\bigcirc }_{02}$ mode converter, a $\mathrm{TE}^{\square }_{10}$ -to- $\mathrm{TE}^{\square }_{40}$ intermediate mode conversion section with a Y-type power divider structure and a $\mathrm{TE}^{\times }_{44}$ -like-to- $\mathrm{TE}^{\bigcirc }_{02}$ intermediate mode conversion section with a novel cross-sector-shaped transition structure are adopted in the design (the superscript symbol $^{\square }$ represents the rectangular waveguide, $^{\bigcirc }$ represents the circular waveguide, $^{\times }$ represents the cross waveguide). The simulation results show that the transmission coefficient (S21 parameter) of the designed $\mathrm{TE}^{\bigcirc }_{02}$ mode converter is better than −0.18 dB in the whole $W$ -band (75–110 GHz), and the corresponding mode conversion efficiency is larger than 96%. Cold test results show that the transmission coefficient is higher than −1.9 dB and the reflection coefficient (S11 parameter) is less than −15 dB in the frequency range of 75–110 GHz.