利用电导率等效方法对345 GHz折叠波导行波管中的电磁信号的传输损耗进行了仿真研究，考察了流通管孔径、加工粗糙度等对冷腔传输损耗的影响。结果表明，流通管孔径较大或加工粗糙度较大都会导致电磁信号传输严重衰减。模拟分析了热腔中电磁信号衰减对慢波结构净增益、带宽、最佳周期数等器件特征参数的影响，结果显示，电磁信号衰减会使得增益下降和带宽降低。

The equivalent-conductivity method is applied to the simulation work of electromagnetic transmission attenuation for 345 GHz FWG-TWT(folded waveguide traveling-wave tube). The paper studies the “cold” model of slow-wave structure and does research on the big factors which influence transmission attenuation, such as the beam tunnel’s diameter, processing roughness. A big beam tunnel or a large roughness will result in serious electromagnetic attenuation. The paper also studies the “hot” model of slow-wave structure, and analyzes the effects of electromagnetic attenuation on gain, bandwidth, best length of slow wave structure. Results show that electromagnetic attenuation causes gain reduction and bandwidth decreases.