Research On Radar Target RCS Imaging Measurement Method

Radar cross section(RCS)measurements have important applications in radar detection and target recognition.The research project of major scientific instruments carried out research on the electromagnetic scattering mechanism of the plasma sheath coated target,and carried out RCS measurement.High-precision RCS measurement has high requirements on the background environment,but in the research project of major scientific instruments,the measurement background is a high-temperature vacuum cavity,and there are many clutter interferences,which leads to large measurement error of RCS.Synthetic Aperture Radar(SAR)imaging technology has two-dimensional resolution capability in azimuth dimension and distance dimension,and has great advantages in solving the above problems.Based on the two-dimensional SAR imaging technology and the RCS imaging measurement method as the main content,this paper proposes a high-precision RCS two-dimensional imaging measurement method combining background cancellation technology and direct imaging extraction RCS algorithm under polar coordinates.Finally,this paper designs the control scheme of RCS measurement system and develops its supporting software.The main work of this paper is as follows:1.The basic principle of the step frequency SAR imaging algorithm is studied and verified by simulation and experiment.Firstly,the one-dimensional high resolution principle of step frequency signal is introduced.Secondly,according to the engineering requirements of major scientific instrument development projects,the imaging geometric relationship,azimuth resolution,antenna beam width selection,scanning speed requirements,imaging performance indicators and window function selection are introduced in detail.Then,from the perspective of digital signal processing,the Back Projection(BP)imaging algorithm based on step frequency signal is deduced in detail.Finally,the BP imaging algorithm is verified by two-dimensional imaging simulation based on scattering center model,twodimensional imaging simulation based on FEKO and two-dimensional imaging experiment in microwave darkroom.2.Based on the BP imaging algorithm,the RCS imaging measurement method is studied.First introduced the basic theory of RCS measurement.Secondly,two background cancellation techniques,time domain cancellation and frequency domain cancellation,are introduced.Through the frequency domain background cancellation experiment,the improvement of the background of the background cancellation technology is illustrated.Then the RCS one-dimensional imaging measurement method was studied and its performance was evaluated by FEKO simulation experiment.Finally,the relationship between SAR image and RCS in Cartesian coordinate system and polar coordinate system is studied.The FEKO simulation experiment shows that the polar coordinate method has higher accuracy than the Cartesian coordinate method.Based on the above conclusions,a high-precision RCS two-dimensional imaging measurement method based on background cancellation technology and direct imaging extraction RCS algorithm in polar coordinate system is proposed.3.The RCS measurement system control program was designed and its supporting software was developed.The components of the RCS measurement system are first introduced.Secondly,the design of RCS measurement system is introduced in detail,including the remote control of the VNA,the selection of the trigger mode of the VNA,the motion control of the linear guide,the requirements of the control card and the timing control of the RCS measurement system.Finally,the RCS measurement system software is introduced from the three aspects of demand analysis,key technology and functional modules.