基于反射型延迟线结构的无线无源声表面波测温系统

从传感器核心元件及无线测温雷达的优化设计出发,研制了一种集成电子标签的高性能声表面波(SAW)无线无源测温系统。基于耦合模(COM)理论对作为传感元件的反射型SAW延迟线进行了优化设计,基于仿真结果,实验研制了采用YZ LiNbO_3石英基片的434 MHz反射型SAW延迟线,该器件是由一个换能器与8个反射器构成的反射型延迟线,其中3个反射器用于温度检测,另外5个反射器则用于采用相位编码的电子标签。测试结果显示所研制的反射型SAW延迟线具有良好的时域特性与较高的信噪比,并与理论仿真结果极为吻合。设计并研制了采用步进调频(FSCW)模式的测温雷达,利用高精度高低温箱对所研制的无线无源SAW测温系统进行了无线测试,系统表现出良好的线性特性,测温准确度达到了士1℃以内。

Development of a SAW wireless and passive temperature sensor incorporating reflective delay line

Based on optimal design on the core element of the sensor, a wireless and passive surface acoustic wave (SAW) temperature integrated with ID Tag was presented. A reflective delay line consists of a transducer and eight reflectors on YZ LiNbO3 substrate was fabricated as the sensor element, in which, three reflectors were used for temperature sensing, and the other five were for the ID Tag using phase encoding. Single phase unidirectional transducers (SPUDTs) and shorted grating were used to structure the SAW device, leading to excellent signal to noise ratio (SNR). The performance of the SAW device was simulated by the coupling of modes (COM) prior to fabrication. Using the network analyzer, the response in time domain of the fabricated 434 MHz SAW sensor was characterized, the measured S11 agrees well with the simulated one, sharp reflection peaks, high signal/noise, and low spurious noise between the reflection peaks were observed. Using the radar system based on FSCW as the reader unit, the developed SAW temperature sensors were evaluated wirelessly. Excellent linearity and good resolution of ±1℃ were observed.