微波电真空器件随着频率的升高,不但聚焦系统难以实现，而且其输出增益和带宽都受到很大的限制,要解决该问题,建议采用扩展互作用速调管,采用分布作用谐振腔技术来扩展其工作带宽和提高增益。利用CST和粒子模拟(PIC)3维软件对其工作在Ku波段扩展互作用速调管进行了设计和仿真，在工作电压30 kV、束流8.5 A的条件下，聚焦系统采用幅值为0.48 T的周期反转永磁聚焦，在输入功率为5.1 W时，得到效率为23%，3 dB带宽为306 MHz,频带内最大增益为39 dB，其峰值功率为58 kW的微波输出。

With the increase in frequency, the output gain and bandwidth of microwave vacuum devices are subject to considerable limitations, which may be solved by extended interaction klystron. With the same working principle as high-power klystron’s, the extended interaction klystron uses distribution function cavity technology to expand its operating bandwidth and gain. In this paper, a Ku-band extended interaction klystron tube is designed and simulated with PIC (particle-in-cell) three-dimensional software and CST. At the working voltage of 30 kV, beam current of 8.5 A, when the PPM-Focusing system of 0.48 T is adopted, and the input power is 5.1 W, the microwave output can be obtained with an efficiency of 23%, peak power of 58 kW, 3 dB bandwidth of 306 MHz, and the largest in-band gain of 39 dB.