从行波管工作的物理特性提出了一种获得折叠波导慢波结构参数的简单方法，给定工作频率和电压，能够获得折叠波导慢波结构的初始参数.设计了D波段的折叠波导结构来验证该方法，对其冷测特性如色散、耦合阻抗进行了分析.仿真结果表明，设计的折叠波导慢波结构在中心频率处具有较平缓的色散关系，在中心频率处耦合阻抗为3.5欧姆.在电子注电压为20.6kV，电流为15mA时，27mm(50个周期)的折叠波导慢波结构在220GHz具有13.5dB的增益，3dB带宽为11GHz (213~224GHz).同时讨论了折叠波导慢波结构的微加工工艺，并通过UV-LIGA工艺获得了实验样品.

A simple method based on the physical characteristics to get the main parameters of folded waveguide traveling wave tube (TWT) circuit is presented. Providing the operating frequency and beam voltage, the authors can obtain the initial structural parameters of the FWTWT. A D-band folded waveguide circuit was used to verify this method. The cold characteristics including dispersion relation and interaction impedance were analyzed. The simulation results show good agreement with their theory formula analysis. The folded waveguide slow-wave structure has flat dispersion relation, fairly high interaction impedance about 3.5 ohms at the center frequency of 220GHz. The large signal performance of 27mm (50 periods) folded waveguide circuit was predicted. Simulations show the nonlinear gain is 13.5dB at 220GHz where beam voltage and current are 20.6kV and 15mA, respectively. A saturated 3dB bandwidth is 11GHz (213~224GHz). The Microfabrication process to produce the folded waveguide circuits was discussed. The first example of the folded waveguide circuit was fabricated by UV-LIGA process.