Design and Test High-Frequency System of G-Band Folded Waveguide Traveling-Wave Tube

220GHz is a very meaningful and valuable atmospheric window frequency band in the low frequency band of the terahertz field. In this paper, the high-frequency system of a G-band folded waveguide traveling wave tube is designed and tested. The simulation results show that under the conditions of working voltage 19460V and current 40mA, the gain is greater than 30dB in the frequency range of 214-224GHz, and the output power is greater than 15W. The high frequency system is processed, and the cold test results show that $S_{11}$ is less than -10dB in the frequency range of 205-240GHz.