Simulation of W-Band Folded Waveguide Traveling Wave Tube with Improved Gain Flatness

W-band traveling-wave tube (TWT) based on the folded waveguide slow wave structure (FWSWS) is simulated to carry out the high power millimeter-wave amplifier. In order to improve the gain flatness, a positive period step section is inserted into the input section in our design. The whole high frequency system is optimized by our calculation. The particle-in-cell (PIC) results predict that the maximum output power of this TWT is 237W and the gain fluctuation is less than 1.2dB in the frequency range of 90-97GHz.