The design, fabrication and cold test of a high frequency system (HFS) for an H-band (220–325GHz) sheet beam travelling wave tube is presented in this article. The HFS was composed of a 90-period double-staggered grating waveguide and a pair of identical L-shaped couplers with Bragg reflectors and matching steps. The HFS was manufactured by nano-computer numerical control machining and its electromagnetic properties were measured by using a vector network analyzer. The measured S-parameters were in good agreement with the simulated ones, which predicted a 3 dB bandwidth of ∼47.0 GHz. The maximum value of the measured transmission coefficient S21 was −4.9 dB and the in-band port reflection S11 was around −15.0 dB. Based on the cold testing-based HFS, simulations of the beam wave interaction predicted a stable output power of over 55.1 W in the frequency range of 230–280 GHz. In addition, the instabilities of the beam wave interaction were investigated in the simulation.

中文翻译：

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H波段薄板行波管高频系统的设计、制作及冷测

本文介绍了用于 H 波段 (220–325GHz) 片状波束行波管的高频系统 (HFS) 的设计、制造和冷测试。HFS 由一个 90 周期双交错光栅波导和一对具有布拉格反射器和匹配台阶的相同 L 形耦合器组成。HFS由纳米计算机数控加工制造，其电磁性能通过矢量网络分析仪进行测量。测得的 S 参数与模拟的非常一致，模拟的预测 3 dB 带宽约为 47.0 GHz。测得的透射系数 S21 的最大值为 -4.9 dB，带内端口反射 S11 约为 -15.0 dB。基于基于冷测试的 HFS，光束波相互作用的模拟预测超过 55 的稳定输出功率。在 230–280 GHz 频率范围内为 1 W。此外，在模拟中研究了束波相互作用的不稳定性。