Microwave Radar With Transponder For Displacement Measurement In Structure Health Monitoring

Large infrastructure is the foundation of the national economic development and people's living.Its structure health and safe operation are highly valued by whole society.Structure displacement/deformation is one of the most important parameter which indicates the structure health status.Among the displacement/deformation monitoring methods,microwave radar technology catchs the attention of the researchers because of its great monitoring potential of all-weather,long distance,high accuracy,low cost,etc.The stepped-frequency continuous wave(SFCW)radar sensor can reach the precision of millimeter deformation monitoring at hundreds of meters measurement distance,but it has a technological monopoly and high price.To break the technical monopoly and bottleneck of price,Doppler radar system has been studied from propagation loss,microwave leakage and multipath reflection aspects.Several researches has been accomplished as following:(1)According to the requirements of the structure three-dimension deformation monitoring,the deformation relationship between one-dimension and three-dimension has been derived,so has the accuracy;(2)Microwave radar with transponder system has been proposed,it gives a total solutions to propagation loss,microwave leakage and multipath reflection problems.And the system performance has been analyzed.(3)From the system schematic diagram,the parameters for each part are calculated.Parts selections and circuits design are completed.The rationality and validity are tested.(4)According to the Fast fourier transform principle,two channel signals' phase difference demodulation system has been developed based on the FPGA board.(5)Hardware circuits and software system are combined.Outdoor experiments has been designed and conducted to test the whole system's displacement/deformation monitoring performence.