【作者】 李平；

【导师】 黄尚廉；

【作者基本信息】 重庆大学 ， 仪器科学与技术， 2003， 博士

【摘要】 无源无线传感器技术是现代传感技术的重要研究内容之一。在易燃、易爆、高温、低温、高电压、强电磁场、强加速度、运动物体内部和许多其它传感器无法应用的特殊场合，声表面波无源无线传感器,具有其它传感器无法比拟的优点。它不仅能构成多参量传感器和阵列传感器，而且还可同时实现编码器的功能，应用于目标识别、商品防伪和智能交通系统中，因此，研究无源无线传感器具有十分重要的学术意义和广泛的工程应用前景。对无源无线传感器的已有的研究工作主要集中在对延迟型声表面波传感器和目标识别器的原理和应用方面。由于延迟型器件的Q值较低，蓄能性能较差，用作无线查询的无源传感器，无线遥测距离短，限制了这类型传感器的应用。本文针对这一问题，以谐振器型和谐振延迟型无源无线声表面波传感器为研究对象，对传感原理、信号处理方法和仪器系统的构成实现，从理论和系统实现两个方面进行了深入研究，取得了有价值的结果。本论文主要研究工作如下：1. 提出了一种谐振延迟型无源无线声表面波传感器，它兼有延迟线和谐振型声表面波传感器的优势，能够在较远的距离实现编码和传感的功能，从而避免了延迟线型和谐振型声表面波传感器各自的不足，扩大了应用的范围。推导了谐振延迟线型无源无线声表面波传感器对激励信号的响应特性，建立了相关的实验系统。进行了温度实验，验证了理论分析和系统设计的正确性。2. 推导了单端口声表面波谐振器的冲激响应特性和对间歇正弦激励信号的响应。并对推导进行了仿真和物理实验结果对比。分析了谐振器的结构和各部分的工作原理，以及谐振器的等效电路和稳态响应特性。3. 按照软件无线电的思路，采用虚拟仪器技术，应用个人计算机作仪器平台，使用尽可能少的硬件、更通用的电路结构和模块化设计实现了无源无线声表面波传感器仪器系统。它能作为谐振型传感器的无线收发系统，也可实现谐振编码型的无线收发系统。在该虚拟仪器系统中，完全由软件产生的DDS（直接数字合成）信号，实现高分辨率的、小步长、宽范围信号频率调节，进行传感查询。仪器系统自动捕捉传感器的工作频带，跟踪传感器的谐振频率。解决了收发开关泄漏对接收信号的非线性影响。在信号处理中，采用自适应信号预处理，防止频谱混叠，从而有效提高接收信号的信噪比。对短小天线进行设计和调试，分析了匹配网络的影响。对于标准的偶极子天线实现了10米以上的测量距离，而15厘米的小天线也达到了4米以上的测量距离。4. 分析了无源无线声表面波传感器信号和各种主要噪声的特点，针对传感器无线回波信号强度非常微弱，采取了抑制噪声和改进信噪比的相应措施，提出了一种新的提高信噪比的回波中心频率的自适应检测和估计方法。该方法已经过大量的实验验证。 <WP=6>5. 提出了利用声表面波器件将电磁能提供给传感器和电路工作的“自供电”的概念及一种电磁能聚集、储存的声表面波自供电工作原理和结构，设计出一种电磁自供能系统。还根据正逆压电效应，介绍了机械能自供电的原理，并设计出相应的机械结构。分析了采用自供电系统对传感器性能的改善，指出采用自供电系统将大大提高传感器的传感距离，从而扩展应用领域。此外，针对石英材料与其它结构连接时存在的热应力，介绍了一种一体化微机械加工石英的方法，该方法能得到高的宽高比微型立体结构，彻底消除热应力。该方法也为在石英材料上构造各种微传感器提供了一种手段。6. 分析了在各向同性介质和各向异性压电介质中声表面波方程，从而求得瑞利波的质点位移和传播速度。建立了叉指换能器的函数声辐射模型，分析了它的工作原理及特点。建立了它的交叉场和共线场等效电路模型，根据此模型分析了叉指换能器的网络方程、输入导纳和辐射特性。对声表面波器件的设计和加工工艺特点进行了研究。7. 分析了压力、振动、质量负载及电参量等多种参量在实际应用中对无源无线声表面波温度传感器系统的影响，提出了减小或消除这些参数影响的措施。对无源无线声表面波阵列传感器进行研究。分析了频分复用和编码式传感器阵列原理，构造了阵列传感器的结构。8. 在模块化、通用化无源无线声表面波传感器实验系统的基础上成功研制了NI 6115和NI 5102两种数据采集模块的虚拟仪器系统。用两种虚拟仪器系统进行原理研究和温度传感实验分析。分析其数据分布、误差和测量精度，优化实验系统，提高测量精度。更多还原

【Abstract】 Passive wireless sensor technology is one of important aspects for modern sensor techology. In the inflammable and explosive measurement, high temperature, low temperature, high voltage, powerful electromagnetic field and some other special application, passive wireless surface acoustic wave(SAW) sensor has more advantages than other sensors. It can constitute not only sensor array, but also encoder and decoder. It can be used for target recognition and smart traffic system. Therefore, the study of passive wireless sensor has scientific and engineering significance.The studies on the passive wireless sensors mainly focus on delay SAW sensors and ID-tag. Because the quality of the delay SAW device is very low, it only can be used for detecting in short distance. In this thesis, the principle, signal processing and instrument system of the resonator and the delay-resonator passive wireless SAW sensors are studied, and some valuable results have been obtained. The main work is provided as follows:1. A new delay-resonator passive wireless SAW sensor is proposed. It has both delay line and resonator advantages, so it can be used in longer distance. Its response characteristic for impulse signal is deduced. And the experiment system is constructed.2. Responses of one-port SAW resonator for impulse signal, sinusoidal burst signal and steady-state are deduced. Principle and equivalent circuit of one-port SAW sensor are analysed.3. According to software radio method, a passive wireless SAW sensor transceiver system by using the NI virtual instrument, the personal computer, the universal circuits and the module is realized. A signal generator of high-resolution, automatic search is accomplished by using the direct digital synthesis (DDS). The nolinear effect of the transmiting-receiving switch is eliminated. In processing circuit, the programmable gain amplifier (PGA) is used for different signal amplitudes. The match network in antenna is analysed. 4 meter detecting distance is obtained in 15 cm dipole antenna.4. The characteristic of the signal and the main noises is analysed. A new frequency evaluation method is proposed. The signal/noise ratio can be improved by using this method. And many experiments have shown that this method is correct.5. A concept of self-generating of electromagnetic energy in SAW device is proposed. Its principle is analysed. Its structure and system are designed. According to piezoelectric effects, the principle and the structure of self-generating of mechanic energy are also introduced. This thesis analyses the properties of self-generating sensors and shows that the detecting distance will be improved greatly. So it can be used for more application fields. Besides, a micro-manufacturing <WP=8>procedure of quartz is introduced. The micro three-dimensional structure with high width-height ratio can be obtained by this procedure. Therefore, the thermal stress between sensor and exterior structure can be eliminated by using integration technology.6. The SAW wave functions in isotropic and anisotropic medium are analysed. The acoustic radiation module of function in the interdigital transducer (IDT) is introduced. Its principle and characteristic are analyzed. The module of cross field and longitudinal field is set up. The network equation, input admittance and radiation characteristic are analyzed.7. The effects of pressure, vibration, mass loading, conductivity and other parameters in applications of passive wireless SAW temperature sensor are analyzed. The prevention of the effects is discussed. In applications of frequency division multiplexing (FDM) and encoding passive wireless sensor array, the sensing principle and the structure are analyzed.8. The two modularized and universal passive wireless SAW sensor experiment systems are developed by using NI6115 and NI5102 virtual instruments. The principle research and temperature experiment analyses in the virtual instrument experiment system are accomplished. The error analysis is finished. The experiment system is optimized. Th更多还原