Development of a Ka-Band Circular TM₀₁ to Rectangular TE₁₀ Mode Converter

Abstract

The output/input circuit is a core component in all high-power millimeterwave (MMW) radiation sources, and its performance specifications and reliability directly impact upon the performance of the radiation device. Central to achieving high output power is the development of efficient mode converters. Here we report on the development of , a compact ka-band circular waveguide TM01-rectangular waveguide TE10 mode converter. The present mode converter adopts an all-metal waveguide structure and facilitates notable improvement in the system power capacity and is capable of realizing high-power propagation. The mode converter realizes effective mode conversion between high-order and fundamental modes, as well as allowing longitudinal and transverse transmission. Our simulation and empirical findings have shown mode purity as high as 96% in the frequency range of 32.7 -34.6 GHzwith a return loss S11 < -19.3 dB. The bandwidth of the converter is 2.4 GHz with transmission coefficient S21 ≥ -1 dB. We anticipate these results will provide a strong foundation for the development of ever more sophisticated and high power, compact vacuum electron devices and advanced radiation sources.

A Carbon Nanotube-Based Hundred Watt-Level Ka-Band Backward Wave Oscillator

“…The electron beam then interacts with the high frequency field (circular TM01 mode). Finally, the high frequency circular TM01 signal is output as a rectangular TE10 mode through the mode converter (iii) [19] as the electron beam reaches the collector (ii).…”