采用粒子模拟方法对一种基于过模结构的表面波振荡器相对论太赫兹源进行了研究，模拟得到了频率为0.148 THz的电磁波输出，主要输出模式为TM01模式。该结构的特点是没有反射结构，电磁波会进入二极管区域。研究了电子束电压和二极管区域内电磁场对输出功率和频率的影响以及器件几何结构参数对输出功率的影响。计算结果表明，泄露到二极管区域的电磁波对器件工作状态影响很小，但是二极管参数对器件的输出功率影响很大。

A relativistic surface wave oscillator based on overmoded structure is simulated with particle-in-cell method. The output signal is generated with a frequency of 0.148 THz and the main output mode of TM01 according to numerical results. The electromagnetic field may leak into diode region because the device is lack of effective reflector. The characteristics of this device and the influence of the parameters of diode on the device are studied via particle simulation. The simulation results indicate that the electromagnetic field leaking to diode region has little impact on the work status of the device but the output power is affected by the structure of diode seriously.