Study On Target RCS Measurement Method Based On Radar Imaging

With the development of stealth technology of weapons and equipment and the continuous improvement of radar detection capability,the research on the measurement method of target scattering characteristics has gradually become one of the hot spots.Radar Cross Section(RCS)is an important physical quantity to characterize the electromagnetic scattering characteristics of targets,and the development of its measurement technology becomes more and more important.Traditional RCS far-field measurement and compact field measurement have some problems,such as high cost,great environmental impact or limited size of the target to be measured.Moreover,these two measurement methods can only obtain the comprehensive equivalent area of the target RCS,but can’t reflect the scattering characteristics of the local structure of the target.As an important means to obtain the spatial distribution of the scattering coefficient of the target,radar imaging technology can be applied to RCS measurement,which can reduce the test conditions and obtain richer scattering information of the target.Based on this background,aiming at different imaging dimensions and scanning methods,this thesis mainly studies three different imaging types: near-field 2D turntable imaging,near-field planar scanning 3D imaging and far-field 3D turntable imaging.Based on the obtained radar images,the target scattering center extraction and RCS inversion are carried out,and finally the target RCS is obtained,which can provide certain technical support for target RCS imaging measurement in different application scenarios.The main research contents and achievements of this thesis are as follows:1.Aiming at the requirement of near-field measurement of target RCS,the measurement method of target RCS based on near-field two-dimensional turntable imaging is studied.Firstly,the geometric model and basic principle of two-dimensional turntable imaging are expounded,and the processing steps of back projection imaging algorithm are deduced.Then the target scattering center extraction algorithm and RCS inversion algorithm based on scattering center model are introduced.Finally,simulation experiments are carried out on different types of target RCS inversion,which verify that the target RCS inversion method based on radar imaging can successfully invert the far-field scattering characteristics of the target according to the near-field measurement data.2.Aiming at the problem that the two-dimensional image can’t fully reflect the three-dimensional scattering information of the target,the RCS measurement method of the target based on near-field planar scanning three-dimensional imaging is studied.Firstly,the geometric model of near-field planar scanning3 D imaging is established,and the imaging principle of 3D wavenumber domain imaging algorithm is deduced in detail.Then,the image-based scattering center extraction algorithm and target RCS inversion method are extended to the three-dimensional situation.Finally,the algorithm is verified and analyzed by simulating the near-field scattering data of different types of targets.The experimental results show that this imaging algorithm can accurately reconstruct the three-dimensional scattering image of the target,and the RCS inversion algorithm has a good effect on the measurement of different types of targets.3.Aiming at the requirement of 3D RCS measurement of moving target,the RCS measurement method based on far-field 3D turntable imaging is studied.Firstly,the imaging model of three-dimensional turntable is established,and the fast imaging algorithm of three-dimensional Fourier transform is introduced based on the far-field condition.Then the theory of compressed sensing is applied to ISAR 3D imaging,and the algorithm flow of 3D imaging based on compressed sensing is deduced.Finally,the RCS inversion method based on two imaging algorithms is simulated and verified.The experimental results show that,compared with the Fourier transform-based method,the method based on compressed sensing can reconstruct the 3D image of the target with high precision under sparse sampling conditions,which significantly reduces the burden of the data acquisition system.Moreover,the obtained image has no sidelobe effect,and the accuracy of RCS inversion is higher.