Research On Technology Of Rebound Jamming And Anti-Jamming To Spaceborne SAR

Modern war pays more attention to enhance the ability to obtain information,and SAR has excellent access to get information,in addition,spaceborne SAR is able to achieve a large area and high-resolution military reconnaissance in high altitude,so that it plays an irreplaceable role in the electronic warfare.With the advantages of low cost,simple realization,diverse interference patterns and good interference effect,the rebound jamming mode has become an important means of interference in the future electronic warfare.Therefore,it is necessary to study the rebound jamming and anti-jamming to the spaceborne SAR.First of all,this thesis introduces the principle of SAR imaging,analyzes the propagation path of rebound jamming signal,and establishes the spatial geometric model of spaceborne SAR rebound jamming.Through the analysis of radar target echo and rebound jamming signal imaging mechanism,the author found that the imaging results were the superposition of the real image and the virtual image.The virtual image was the deformation and displacement of the real image.The jammer position and the forwarding time delay were two important parameters that affected the effect of the rebound jamming imaging.In this thesis,a distributed rebound jamming mode is proposed for the concealment of jammers,and its spatial geometric and signal model are analyzed.Furthermore,according to the RD algorithm of SAR imaging,the signal form of the rebound jamming is deduced after distance compression and azimuth compression,and the position formula of the virtual image is obtained.According to the displacement characteristics of the virtual image,the separation conditions of the virtual image and the real image and the position of jammers are analyzed.Simulation experiments show that the effect of rebound jamming imaging is different for different forwarding time delay modes.Finally,based on the imaging mechanism of rebound jamming,the research on rebound anti-jamming of signal field and image field is carried out.In the signal filed,the method of two-channel rebound anti-jamming is studied.In the image field,the basic principle of rebound anti-jamming and the imaging influence of jammer position parameters are studied in this thesis.In addition,the method of estimating the position of jammer using virtual image is studied.On this basis,an anti-jamming method based on jamming signal reconstruction is proposed,and its error influence and applicability condition are analyzed.The correctness and validity of the method are verified by simulation.