Study On RCS Measurement Based On Compressed Sensing 3-D Imaging

With the development of UAV,stealth aircraft and other related technologies,targets Radar Cross Section(RCS)measurement technology has become more and more important in the fields of reconnaissance and anti-reconnaissance,stealth and anti-stealth.RCS measurement can be divided into theoretical calculation with electromagnetic method and practical measurement on real targets.The computation quantity of theoretical calculation is heavy,and there are difficulties applying to targets with complex structures or composite materials.In practical measurement,some problems such as high environmental requirement,target size limit or high cost of experiment exist in conventional far-field measurement and compact-range measurement.3-D imaging RCS measurement is a new target RCS measurement method that started late.Based on the characteristics of the method itself,it has natural advantages in solving the problems above.3-D imaging RCS measurement technique based on plane-wave synthesis is a kind of near field 3-D imaging technology,which has the ability to invert far field RCS.In this paper,the problem of large number of measurement points lead to long measurement time and large amount of data in the RCS measurement based on plane-wave synthesis is studied,the problem of RCS measurement accuracy influenced by special targets' echoes with phase reversal is studied,specific work and innovation are as follows:1.The working mode and signal model of Linear Array Synthetic Aperture Radar(LASAR)3-D imaging are summarized,the transmitting signal form is introduced,a common imaging algorithm-3D Back Project(BP)algorithm is introduced.On this basis,the plane-wave synthesis theory is introduced,the relation between BP operator and synthetic plane-wave is analyzed,the 3-D imaging and RCS inverting process of 3-D imaging RCS measurement technology based on plane-wave synthesis is introduced in detail.The basic principle of compressed sensing imaging including sparse representation of signal,design of dimensionless observation matrix and sparse reconstruction algorithm is introduced.2.In order to solve the problem of large number of measurement points in spatial domain,the performance of RCS measurement method based on plane-wave synthesis in sparse array is analyzed by simulation,the compressed sensing theory is introduced to study RCS measurement method based on compressed sensing.By establishing a comprehensive linear measurement model of plane-wave synthesis and designing appropriate sparse transformation matrix and dimensionless observation matrix,this method will greatly reduce the number of measurement points required for RCS measurement.3.Aiming at the problem of high requirement on the number of frequency sweep points,the feasibility and key points of sparse frequency imaging based on plane-wave synthesis are analyzed.The RCS measurement model of sparse frequency based on plane-wave synthesis is established.Based on the model,an improved 3-D BP algorithm is proposed,and the effectiveness of the method is verified by simulation.Finally,the effects of two typical frequency sparse modes on the measurement results of RCS are analyzed.4.Phase reversal in special targets' echoes is introduced through measured data,the principle of its generation and influence on RCS measurement are analyzed.To solve the above problems,an RCS measurement method based on sub-array adaptive imaging is proposed,the whole array is segmented adaptively according to the coherence of echoes,each sub-array calculates the RCS of corresponding angle independently,the interference of phase reversal on RCS measurement is reduced and the accuracy of RCS measurement is improved.