Design of 0.27-0.37THz Wideband Coaxial Line to Double-ridge Waveguide Window for Traveling-Wave Tube Amplifier

A wideband coaxial line to double-ridge waveguide window for broadband high power THz TWT has been studied in this paper, which can cover the 270-370 GHz with a ultra-bandwidth over 0.1 THz. Based on the mode conversion theories and impedance matching techniques, the broadband transition of coaxial line to double ridge waveguide is designed. In addition, the diamond is adopted to design the broadband double ridged waveguide window. The characteristics of the transition are analyzed by using the full-wave analysis software. According to the simulated results, the reflection coefficient is less than -20 dB and the VSWR is less than 1.2 in the 270-370 GHz.