Development of W-band Full Bandwidth TE10-TE20 Mode Converter

The next generation of W-band slow wave structure traveling wave tube has driven great demands of waveguide TE10- TEn0 mode converter with high performance of low loss, wide bandwidth, conversion efficiency. In this paper a mode converter of E-plane TE10 to H-plane TE20 working on the full W-band is developed. In order to verify the mode converter performance, a transformation structure with high efficiency is also adopted. Firstly, the characteristic of TEn0 mode distribution in the waveguide is analyzed. The E-plane power divider, the waveguide twist and the out-of-phase power combiner are proposed and integrated. Secondly, the overall scheme of such TE10-TE20 mode conversion is optimized. Finally, this structure is integrated with H-plane out-ofphase power combiner to realize the measurement. This W-band module is fabricated based on CNC technology and measured with three ports. The measurement results, which are agree well with the simulation, show that this module has achieved power distribution ratio of -3. 2 dB ± 0. 2 dB, phase difference of 180° ± 2°, and the return loss is better than -20 dB within the full W-band. The above results verify the high efficiency, low loss, feasibility and robustness of W-band wideband TE10-TE20 mode converter.