Design And Realization Of The Radio Frequency Coaxial Cable Grating Sensor

Safety monitoring of important facilities and rock mass landslide has become one of the most popular topics in the world. The existing strain sensing components can not meet the requirement of practical application because of its small test range and the difficulty of full-range/real-time monitoring. Damages caused by extreme loads and disasters (or catastrophes) are becoming a bottleneck to safety monitoring on the major infrastructureand landslide.Therefore, this thesis proposed a raster-type strain sensor based onRF coaxial cable, which can realize the structural safety monitoring with wide measurement range. Compared with the traditional optical fiber Bragg grating sensor, the new developed sensor takes the radio frequency coaxial cable as its transmission medium. The data acquisition of strain test depends on the transmission characteristics of the radio frequency signal in the coaxial cable. To better conduct engineering applications, the thesis puts forward the structure of the capacitance-loaded coaxial resonant cavity for impedance discontinuity research, for the first time in the field of sensors. The main contents of this thesis as follows:(1) Firstly, the theory of Bragg grating of the RF coaxial cable is well studied. By analyzing the mechanism of the coaxial cable and the RF theory of the capacitance-loaded coaxial resonant cavity, the Bragg grating for new RF coaxial cable is theoretically researched.(2) Secondly, the simulation design is realized by Ansoft HFSS 3D electromagnetic field software. According to the structure of capacitance-loaded coaxial resonant cavity and practical application, the feasibility of this method theoretically analyzed. Further, I built the 3D simulation model of the capacitor-loaded resonant cavity and coaxial cable. This thesis studied the structure of the electrical grating of coaxial cable sensor.(3) Then, the study designed the mechanical structure of the capacitor-loaded coaxial resonator cavity, and achieved the production of device; also introduced the implementation process of the sensor. To achieve the purpose of engineering applications, the sensor signal transmitter and receiver equipment is brieflyintroduced.(4) At last, the transmission characteristics of coaxial cable Bragg grating sensor were studied and analyzed. By collecting and analyzing data we can get the strain curves and the temperature characteristic of the coaxial cable Bragg grating sensor, and verifiedits stability for long term.In this thesis, the coaxial cable Bragg grating sensor is proposed using the mechanical structure of the capacitance-loaded coaxial resonator. We manufactured the coaxial cable grating sensor, and the test data can meet the requirements of engineering application. At the same time, the idea of this research hasreference significance for future RF coaxial cable sensor.