双通道MEMS微波功率传感器的匹配特性

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1.6μm时,该传感器在测量8~12GHz频率内的微波信号时,回波损耗小于-19dB。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。

Impedance matching of MEMS double-channel microwave power sensor

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.