The Study On Transmitter Techniques For Impulse Ground Penetrating Radar

Impulse Ground Penetrating Radar (GPR) is a kind of non-destructive detectingtechnique employing Ultra-wide band (UWB) impulse signal to survey the shallowlyburied objects, with the advantages of high resolution, easy operation and low cost. Acompleted GPR system consists of main frame, transmitter (Impulse Source), receiver,transmitting and receiving antenna, and the Impulse Source, one of the core blocks ofRadar system, will be discussed within the field of this thesis in details.In this thesis, the current research status and performances of the GPR pulsesources are summarized; the principle of avalanche transistor is analyzed, especiallythe mechanism of avalanche, breakdown voltage and dynamic process of avalanche;some normal kinds of Avalanche Transistor circuits are analyzed and experimentalvalidated selectively. Based on the principle of avalanche effect a evaluation model ofAvalanche Transistor is built up, and the generation process of the Avalanche ImpulseSignal is simulated, also, the components selection, operating voltage setup andperipheral circuit design are discussed in details, respectively; Compared thesimulation result with the experimental outcome, this evaluation model can effectivelysimulate the dynamic process of the Avalanche Transistor, and provide a validtechnical method for the evaluation model design of the Avalanche Transistor circuits.A series pulse generator with Avalanche Transistor are designed and carried outbasing on the simulation results, generating the right pulses with the rising time lessthan 1ns, 1～10ns duration and 50～1000v amplitude, and satisfying the requirementsof depth and resolution for GPR.