Research On 110GHz Radar For Advanced Detection Of Cracks In Bulk Coal

Many water disaster problems that cannot be solved by traditional detection methods have become increasingly prominent. Therefore, it is necessary to study an effective method to detect coal seam fracture to ensure the safety of people’s life and property. Terahertz technology is one of the most promising subjects recently, which can be used to detect the coal fracture with the characteristics of penetration and high resolution.A brief introduction about the development of coal fracture detection technology and terahertz radar technology at home and abroad are presented in the paper firstly. Then, the propagation characteristics of electromagnetic wave and its testing principle are studied as well as the penetration characteristics of terahertz wave to coal medium. Coal classification is investigated, and different kinds of coal samples are prepared. Then a testing system is set up. The electromagnetic wave signal on the range of 75GHz~750GHz can be obtained from the Vector Network Analyzer(VNA) with the spread spectrum module or the signal generator with the spread module, which can test the coefficients of transmission or reflection of the coal medium with a certain thickness and provide a reference for parameters setting of the advanced detection of coal seam fracture as well as the design of the radar system. This paper mainly focuses on the design of radar system and carries out the research work in the following chapters. Firstly, the working frequency, transmitting power and working mode are analyzed and selected taking advantage of the testing system which is designed to test the penetration characteristics of coal seam. Then the transmitter and receiver hardware circuit and data acquisition part of the system are designed according to the parameters selected. The key parameters of the components in the system of the transmitter and the receiver are tested to ensure the robustness of the entire system. Furthermore, the imaging results of different coal samples with fracture at 110 GHz frequency are obtained by the system with the two-dimensional scanning device. Finally, the transmission and reflection imaging results are analyzed and summarized, and the prospect of the 110 GHz imaging system is presented.