为了降低双通道MEMS微波功率传感器的回波损耗, 提高传感器的测量精度, 对MEMS悬臂梁的匹配特性进行了研究。首先, 通过双通道MEMS微波功率传感器结构构建S参数的理论解析模型, 分析了双通道MEMS微波功率传感器的匹配特性, 得到了MEMS悬臂梁的间距和回波损耗系数S11的关系; 接着利用有限元软件HFSS进行仿真, 并和理论结果比较; 然后, 设计并制作了双通道微波功率传感器; 最后, 对该传感器的匹配特性进行了测试和分析。实验结果表明: 当MEMS悬臂梁的间距为1. 6 μm时, 该传感器在测量8~12 GHz频率内的微波信号时, 回波损耗小于-19 dB。理论和仿真结果较为相符, 因此S参数的理论解析模型可以较好地反映双通道MEMS微波功率传感器的匹配特性, 对双通道MEMS微波功率传感器的设计具有一定的指导意义。

To reduce the reflection loss of Micro-Electro-Mechanical System (MEMS) double-channel microwave power sensors and improve their measurement accuracy, it is necessary to investigate the impedance matching of MEMS cantilever beams. First, an analytical model of the S-parameters was constructed using the structure of the MEMS double-channel microwave power sensor. The impedance matching of the MEMS double-channel microwave power sensor was analyzed, and the relationship between the spacing of the MEMS cantilever beams and return loss S11 was obtained. The simulation was performed using a finite element software-high frequency structure simulator (HFSS)-and the simulation results were compared with the corresponding analytical results. Next, a double-channel microwave power sensor was designed and fabricated. Finally, the impedance matching of the sensor was tested and analyzed. The experimental results reveal that for a microwave signal in the frequency range 8—12 GHz, when the distance between the MEMS cantilever beam is 1.6 μm, the sensor has a return loss of less than -19 dB. The analytical and simulation results are in good agreement, confirming that the analytical model of the S-parameters can reflect the impedance matching of MEMS double-channel microwave power sensors. Thus, the analytical model can be used as a guide for the design of MEMS double-channel microwave power sensors.