Investigation of a Modified Flat-Roofed Sine Waveguide Slow-Wave Structure for Wideband 220-GHz TWT

In this letter, the modified flat-roofed sine waveguide slow-wave structure (FRSWG-SWS) is proposed for the wideband high-power sub-terahertz traveling-wave tube (sub-THz TWT), which possesses the advantages of wide operating bandwidth, low loss, minimal reflection, and ease of fabrication. The simulation results demonstrate that the transmission parameter is more than −5.0 dB in the frequency range between 210 and 250 GHz. The beam–wave interaction results indicate that the modified FRSWG can provide over 50 W of output power and 30 dB of gain from 205 to 250 GHz with sheet electron beam with a voltage of 20.8 kV and a current of 150 mA. Finally, we use high-speed milling to fabricate the modified FRSWG by the nano-Computer Numerical Control (CNC) technology. The cold test results demonstrate that the modified FRSWG has low loss and good reflection characteristics.