| The principle of Doppler radar is based on the Doppler effect which is widely applied on science and project. The main task of Doppler radar systems is to measure the Doppler frequency which is proportional to the speed of moving objects, and thus obtain the speed of moving objects. The measurement system under consideration here orients to ordinary moving objects and can be used to construct many practical application system.The thesis designed RF signal source with RF transistor 2SC9018,and the transceiver Yagi-Uda antenna is sharing. The system was consisted of RF oscillator, mixer, low-pass filter and low-frequency amplifier. In this thesis, it discussed the principle and design method of the components above, established the equivalent circuit mode of the RF transistor under OrCAD/PSpice software, and did software simulation to each key circuit of the system. Finally, debugging the actual hardware circuit with the spectrum analyzer and oscilloscope, thereby verified the correctness and feasibility of the circuit design.The frequency of radar is 1004MHz, and the characteristics of the RF circuit is the self-oscillation and self-mixing function, the speed measurement circuit of the Doppler radar is simple, and its cost is low and the price compares is better. |
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