According to the transmission pulse requirements of the impulse-GPR which probes the objectives of shallow soil, a transmission circuit is designed and made. On the basis of the transistor avalanche theory, avalanche transistor and RF transistor are used to generate the impulse-GPR transmission pulse as the core transistors. Trigger pulse is the square wave which is produced by FPGA as the trigger of whole system, its duty ratio under 10% and its frequency from 50 kHz to 500 kHz. As the results of simulation and actual measurement shown, single transistor avalanche circuit and four transistors cascade avalanche circuit can produce a narrow pulse with its pulse width from 1.337ns to 42.91ns. The results meet the transmission pulse requirements of impulse-GPR which probes the objectives of shallow soil.
RF transistor breakthrough in lower-cost plastic
