Raw and analysed filter data for SHM

RF based sensors are an attractive option for structural health monitoring applications due to the ease of access of interrogating such sensors. However, in most work, only scalar quantities are measured giving no indication of direction of strain or displacements. In this paper, a novel approach to displacement sensing is presented in which relative displacements are tracked in all three degrees of freedom. The sensor design is based on a pair of coupled line element filters whose frequency dependent forward power transfer is sensitivity to relative positions between the two filters. Multiple features in the S21 parameter are used to differentiate displacement direction. Gold based devices were fabricated on quartz substrates and characterized through vector network analyzer measurements. Results demonstrate uncoupled sensitivities of -1.41 MHz/mm, -1.74 MHz/mm and 12.23 MHz/mm for x, y and z displacements respectively.

射频（RF）传感器因其问询便捷性，成为结构健康监测（Structural Health Monitoring）应用中的极具吸引力的选择。然而在绝大多数相关研究中，仅能测得标量物理量，无法反映应变与位移的方向。本文提出一种新型位移传感方法，可对三个自由度下的相对位移进行追踪。该传感器的设计基于一对耦合线元件滤波器（coupled line element filters），其随频率变化的正向功率传输特性对两滤波器间的相对位置具有较高敏感性。利用S21参数（S21 parameter）中的多个特征可区分位移方向。研究人员在石英衬底上制备了金基器件，并通过矢量网络分析仪（Vector Network Analyzer, VNA）完成了性能表征。测试结果表明，针对x、y、z三个方向的位移，其非耦合灵敏度分别为-1.41 MHz/mm、-1.74 MHz/mm与12.23 MHz/mm。