| Passive radar has strong anti-electronic jamming,anti-radiation missiles and anti-stealth capabilities,which have attracted increasing attention among researchers.Unlike traditional monostatic radar,the transmitter and receiver of a passive radar sits at different locations.Through reasonable station distribution,it can acquire the scattering signal of a target from multiple directions,which improves the remote sensing and observation ability of the radar system significantly.As one of the electromagnetic scattering characteristics of radar targets,scattering centers are widely used in the radar targets detection and recognition.However,most of the related research on radar target scattering centers is aimed at monostatic scenarios,while the detection of external illuminator radar is a dual-station or multi-station scenario,which puts forward new requirements for the research of radar target scattering centers.This work aims to radar targets bistatic electromagnetic scattering characteristics.The research on the extraction and application of target bistatic scattering center is carried out.The specific work is summarized as follows:1.The monostatic bistatic equivalent theorem is introduced.The mathematical expressions of point scattering center model and the GTD scattering center model under bistatic conditions are given.One-dimensional and two-dimensional bistatic point scattering centers and bistatic GTD scattering centers are extracted for six typical structures.The error is analyzed by parameters of extracted scattering center,the root mean square errors of RCS and the energy ratio of residual signal.The results verify that the effectiveness of the bistatic point scattering center model and bistatic GTD scattering center model.Meanwhile,the results also reveal that bistatic point scattering center model and bistatic GTD scattering center model have their limitations and cannot describe the aspect characteristic for the scattering centers.2.To overcome its drawbacks of being mathematically complex,having too many parameters as well as high computational complexity and memory demand,an attributed scattering center extraction method with alternative optimization and translatability is proposed and demonstrated with numerical simualtions.The results reveal that the proposed method can extract attributed scattering centers well,and achieves a significant reduction in runtime and memory requirement.Then,based on the proposed attributed scattering center extraction method,the bistatic attributed scattering centers for six typical structures and complex targets are obtained.The parameters of extracted bistatic attributed scattering centers are compared with the ones for the corresponding real objects.Results verify that the bistatic attributed scattering center model can correctly characterize the actual bistatic scattering response and effectively describe the bistatic scattering characteristics of the targets.3.Based on target bistatic scattering center extraction technology,bistatic RCS data fitting,compression and extrapolation are studied.Firstly,the bistatic RCS data fitting and compression based on scattering center is studied.The performance of different scattering center models applied to target bistatic RCS data fitting compression in frequency domain,angle domain and frequency-angle are analyzed.Secondly,the target bistatic RCS data frequency extrapolation based on scattering center is studied.The performance of different scattering center models applied to different targets are analyzed.The limitations of of using the scattering centers center method forapplied to RCS data frequency extrapolation are also analyzed.The results show that the scattering center method performs well in the field of target bistatic RCS data fitting,compression and frequency extrapolation. |
