行波管具有高增益、宽带宽、高输出功率等优点，但频率提升到THz 后，输出功率急剧降低，为此采用多注与功率合成的方式提高输出功率。对D 波段折叠波导行波管进行的理论与数值分析表明： 单束的3 dB 带宽为13 GHz(0.134 THz~0.147 THz)， 0.14 THz 处最大增益为20.88 dB；多束合成增益为20.6 dB，3 dB 带宽内合成效率不低于92%。通过微铣削的办法加工完成了2 路折叠波导，并对其传输特性进行测量，对比分析了测试与设计结果。并行多注行波管能够以单束小电流、低聚焦磁场方式工作，可有效提高THz 行波管的输出功率。

Traveling Wave Tube(TWT) bears high gain, wide bandwidth and large output power. However, the output power will decline significantly when the operation frequency rises to Terahertz range. In order to increase the output power of THz TWT by parallel multi-beam and power combination method, theoretical analysis and numerical simulation of parallel multi-beam D band Folded Waveguide-TWT(FWTWT) are performed. The simulation results demonstrate that the method can achieve the power combining output of multi-amplified signals. According to the simulation, single-beam mode behaves flat dispersion characteristics between 0.135 THz and 0.157 THz; the 3 dB gain band is 13 GHz(0.135 THz-0.147 THz) and the largest gain is 20.88 dB at 0.14 THz; multi-beam mode gets 20.8 dB combining gain at 0.14 GHz and the combining efficiency is not below 92% in 3 dB gain frequency range. The structure is fabricated by micro milling with a dimension error below the designed values. The transmission characteristics of D band Two Beams Folded Waveguide Structure(TBFWS) are simulated and tested. The study shows important meaning for achieving high power THz radiation based on nowadays heat cathode level.