Research On The Key Technology Of Microwave Doppler Radar Front-end

With the advent of the era of microwave, millimeter wave, radar has been widely used in the air and outer space. The task of the radar is not only to measure the target distance, azimuth and elevation, but also includes the measurement of target speed. And get more information from the echo of the target for target recognition. Doppler radar which uses the Doppler effect to get positioning, velocity, distance, etc. And then by analyzing the Doppler frequency characteristics of the radar echo such as phase, amplitude and polarization information, we will be able to get various characteristics of the target.This article describes some theoretical knowledge about the Doppler radar, frequency synthesis and receiver, focuses on the frequency synthesizer’s phase noise and spurious and gives the method to improve by analyzing the way. By analyzing the Doppler radar front end gives the 9.6GHz technology solutions. Work involves the entire front end of the device of choice, simulation power splitter simulation design and only pole antenna.Through direct multiplier to achieve Doppler radar front-end transmitted and received signals-9.6GHz and LO signal 8.4GHz. The power of transmitted signal is greater than 21 dBm, and phase noise is better than-112 dBc/Hz@10kHz. The front end of the radar transmits the signals by monopole antenna, which emits or detects environmental interference signal by the control switch.Combined with the theoretical knowledge, the following W band Doppler radar front-end proposes at least two frequency synthesis schemes for X band high quality frequency source. And analyze their advantages and disadvantages through the parameters comparison to determine the technical scheme of the final scheme-interpolation PLL. Processing, testing gives the final test results of 11.675 GHz, phase leakage suppression is better than 80 dBc, spurious suppression is better than 60 dBc,and phase noise is better than-110 dBc/Hz@10kHz. Because the system uses coherent design, the entire system has the same frequency stability of crystal oscillator, which has high stability.