Study And Design Of Pulse Ground Penetrating Radar Front-end

The monitoring of the pipeline under the ground of city,the quality monitoring of the road and subgrade,the survey of remnant landmines of the war,and the investigation of hidden military target,more and more fields are in great need of detecting the unknown situation under the ground,people have paid more attention to the development of pulse ground-penetrating radar(GPR). On this background,an in-depth study about front end of GPR has been carried out in this thesis.First of all, in this thesis, the basic theory of the pulse GPR has been discussed in detail. The basic theory of electromagnetic field, electrical parameters of medium, working principle, detecting principle, technical indexes of pulse GPR have been analyzed in detail. Second, high amplitude time domain pulse signal source and GPR antenna are the important parts of the front end of GPR,the detailed research and design of this have been put into practice. Single stage and MARX cascaded pulse generating circuit based on avalanche transistors have been simulated, analyzed and measured. Third, advantages and disadvantages of the GPA antenna have been concluded, and a novel bow-tie antenna with semiannular arm has been proposed in this thesis. The VSWR, radiant performance and antenna ring has been simulated and measured. Compared to traditional bow-tie antenna with triangular arm, the performances of the modified GPA antenna are improved observably. It is important to the performance of the whole GPR system. Lastly, to prove the value of high amplitude time domain pulse signal source and the modified GPR antenna, collaborative experiments have been carried out. Superior performances and huge value of the high amplitude time domain pulse signal source and the modified GPR antenna designed in this thesis have been further verified.In this thesis, high amplitude time domain pulse signal sources with 64.1V pulse amplitude, 1.5ns pulse width and 156.2V pulse amplitude, 1.6ns pulse width are designed. Collaborative experiments with both pulse signal source and modified antenna have been carried out successfully.