Research On The Imaging Method Of Millimeter Wave Radar For Security Inspection Applications

Since the 21 st century,the international situation has undergone complex changes.Terrorism has risen,and terrorists have carried out several terrorist attacks,causing many casualties.Therefore,human safety inspection has become more and more critical.Traditional screening methods,such as x-rays and metal detectors,are increasingly unable to cope with the growing threat of terrorism.At the same time,with the improvement of radar imaging technology and computer hardware performance,millimeter-wave radar security imaging technology has become a new direction in the security field with its unique advantages.Therefore,the research of millimeter-wave radar security imaging technology is of great theoretical significance and practical value.This article focuses on the millimeter-wave radar mode and the millimeter-wave radar imaging algorithm applied to security inspection.The main research contents are as follows:(1)Because of the problems existing in the existing millimeter-wave radar imaging algorithms,it is mainly required that the aperture must be linear,and only the motion error along the straight line can be compensated.The motion error will affect the imaging accuracy.In this article,three commonly used CSAR imaging algorithms are studied:Back-projection algorithm(BP),Polar Format Algorithm(PFA)algorithm,and fast circular convolution algorithm.The backward projection algorithm is based on the time domain processing algorithm,and the latter two algorithms are based on the frequency domain processing algorithm.Based on studying the principle of the SAR algorithm,the characteristics of these algorithms,such as imaging speed,imaging precision,and imaging quality,are analyzed by simulation.(2)Given the problem of Radar mode selection,combined with the need for security application,Radar hardware resource cost,algorithm complexity,etc.,this article studies the CSAR(Circular Synthetic Aperture Radar)mode and cross array Radar mode’s geometric model,signal echo model,and data sampling.The fast imaging algorithm in the wave-number domain of cross array radar mode is studied,and the imaging simulation is carried out in these two modes.The characteristics of the two methods are analyzed,and the feasibility of applying these two radar modes in security inspection is verified.The radar mode which is more suitable for security inspection research is selected.(3)To solve the low imaging efficiency of the traditional BP algorithm and low imaging accuracy of the fast BP algorithm in CSAR mode,two fast BP algorithms are studied.CMBP(Chirp Modulation Processing Back Projection)algorithm and FFBP(Fast Factored Back Projection)algorithm.The principle formulas of these two algorithms in CSAR mode are derived,and the simulation experiments are carried out.In addition,an improved CSAR fast BP imaging algorithm is proposed.Through simulation comparison,it is verified that this imaging algorithm can effectively improve the imaging speed and achieve high-resolution imaging.