Research On Key Technology Of System Front End Based On FMCW Security Radar

The FMCW radar is a frequency-modulated continuous wave radar.As a short-range measuring radar,it can measure the distance or speed of a static target or a dynamic target.Compared with several mainstream security products on the market,FMCW security radar can completely cover the monitoring area,and has the advantages of no speed blind spot,small distance blind zone,high resolution,and target tracking.This paper designs a front-end scheme of FMCW security radar system working in the 77 g frequency band.The front-end system can have different detection ranges for different detection distances.It is suitable for dividing safety zone,early warning zone and displacement zone with different safety levels and using the same radar detection.The work of this thesis mainly includes the following aspects:According to the application requirements of the actual scenario and the principles of the front-end modules of the security system,the corresponding calculation and indexing of the working frequency band,radar system,system framework,system index and antenna parameters of the security radar overall scheme are carried out.According to the analyzed antenna array parameter index,the design of the shaped antenna is carried out.Finally,the suitable feeding network scheme is selected according to the design scheme of the antenna array.Modeling and simulation design of security radar transceiver antenna.The receiving antenna is a 1*16 microstrip series feed antenna,and the current distribution of each patch on the antenna satisfies the Dolffitchby Schiff distribution.Since the security radar system adopts an antenna scheme of one transmission and two reception,two antennas are used for the receiving antennas.the transmitting antenna adopts a 1*16 microstrip series feed antenna as an array element to form an 8*16 area array antenna,so that the direction of the transmitting antenna can realize the beam forming effect of the double flat shoulder,and the pattern of the The half-power lobe width and gain value of the pencil beam region?the lobe width and gain value at the two shoulders must meet the design requirements of the security radar system.the feed network of the transmitting antenna is designed to reduce the loss.So we choice the structure of the substrate integrated waveguide.The power splitter is a SIW splitter with eight equal power distribution,the phase shifter is a SIW self-compensating phase shifter,and the joint debugging of the power split phase shifter is performed,and finally the sum is proposed.An improved scheme of the power split phase shifter is designed.Starting from the previously calculated security radar front-end system indicators and selected system framework,the 77 GHz radar RF chip of Nanjing Wenzhi Microelectronics is selected as the core chip of the RF circuit,and then the phase-locked loop module matching it is selected according to the design requirements,linear regulated power supply module,ultra-low jitter oscillator,etc.Refer to the manual of each device and the basic guidelines of circuit design,complete the design of the RF front-end system circuit and build a complete circuit to generate the layout.