| Micropower impulse radar is a kind of impulse radar whose power is extremely small as other ultra-wide band radar,it has become the popular topic study in recent years. The weak life signal behind the visible medium is deteced by launching the ultra-wide band extremely narrow pulse in the article. This article mainly studies the hardware circuit and antenna of the micropower impulse radar which is used in life survey. The radar is usually used in many aspects,such as detecting survivors behind the visible medium, like walls and ruins,detecting the existence of enemys in the anti-terrorist fight and treating the people with infectious diseases in clinical medicine,etc.As to the topic of the uses of the micropower impulse radar in the life survey, through researching the transmission properties of electromagnetic wave, principle of the micropower impulse radar and antenna, single pole antenna inside sleeve and helical antenna are analysed which are also simulated by HFSS three-dimensional stereosimulation software,then the hardware circuits of micropower impulse radar is analysed. The ambipolar ultra-wide band pulses is produced by emissive circuit with avalanche effect of radio frequency triode,the echo signal is sampled by the receiving circuit with bridge type sampling points circuit and is extracted by using the amplifying filter circuit.Based on the above researching schemes, the axial helical antenna which has properties of high-gained and strong orientational was designed in the article.The ultra-wide band pulse whose peak voltage is 1.76V, the center frequency is 1.2G, the pulse width is the 924ps, is achieved. The bridge-type diode integral sampling circuit, the delay circuit,the band-pass circuit and so on have been designed. The experimental result shows that the micropower impulse radar has many advantages in life detection, the design of antenna obtains the good result, t simulation and debugging of hardware circuit are also feasible. |
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