The Research And Design Of Radar Transceiver System For Large Span Bridge Deformation Monitoring

With the rapid development of China’s economy,all kinds of large-span bridges came into being.The traditional deformation monitoring method can not meet the requirements of deformation monitoring because of the increasing volume and span of the bridge.In recent years,microwave interference measurement technology has become one of the important means of deformation monitoring of large span bridge because of its unique advantages of high precision,real-time and non-contact measurement.The microwave interferometry technique uses the principle of interferometry to transmit the stepping frequency continuous wave(SFCW)to the spatial,and carries out the inverse Fourier transform on the echo signal containing the target distance information to obtain the one-dimensional distance image of the target.Based on the theory of radar system and the basic principle of differential interferometry,this paper designs a structure of SFCW radar and verifies the feasibility of the system.The specific research includes:1)The system design of bridge deformation monitoring radar.According to the principle of microwave interferometry,the basic parameters of the radar system are calculated and the basic structure of the transceiver system is determined.2)Radar transmission circuit design,designs the circuit based on the DDS + PLL frequency synthesis program,uses the combination of digital attenuator and power amplifier to compensate the signal generated by the signal source.3)Radar receiver circuit and antenna design,introduces the key parameters of the radar receiver,designs the receiving circuit based on zero-IF structure,including low noise amplification circuit,low-pass filter and quadrature demodulation circuit.analysis the advantages and disadvantages of different antennas,designs the high-gain horn antenna for the system.Finally,debugs the hardware circuit system according to the basic idea of "individual-local-module-system".