设计了一种能在S波段和C波段实现稳定输出的高功率相对论速调管放大器，并使用电磁粒子PIC程序进行了模拟研究。模拟结果表明：采用700 kV，4 kA的电子束，在注入微波功率340 kW、注入微波频率分别为2.8 GHz和3.2 GHz的条件下，通过合理选择输入腔和中间腔的结构和工作模式、调节器件输出腔的腔长，模拟实现了S波段(3.2 GHz)和C波段(5.6 GHz)分别为1 GW和490 MW的微波输出，束波转换效率分别约为35%和17%。

With the electromagnetic code, a frequency-tuned relativistic klystron amplifier (RKA) is designed and calculated. It is found that the operation frequency of the RKA can jump across S-band and C-band by adjusting the feeding frequency and the length of the output cavity. A 1 GW averaged power over the oscillator period is generated by simulation, with 700 kV electron beam voltage, 4 kA current, and 340 kW feeding power. The frequency of the output microwave is 3.2 GHz. The efficiency is about 35%. Meanwhile, a C-band microwave with a frequency of 5.6 GHz and a power level of above 490 MW is generated when the feeding frequency is 2.8 GHz and the output cavity length is 3.7 cm. The efficiency is about 17%.