Research On No-linear Motion Trajectory SAR/ISAR Prameter Estimation And Imaging Algorithm

As an emerging radar system,the invention of Synthetic Aperture Radar(SAR)inspired the upsurge of research on radio technology.Beacuse of its high res olution characteristic,it has been widely used in military and civilian fields.With the rapid development of radar technology,people have put forward higher requirements.It requires SAR not only to achieve high-resolution imaging of stationary targets in the case of no-linear trajectories,but also have the ability to reconstruct real information of moving targets.Aiming at these requirements,the following research is carried out in this paper and it can be summarized as follows:(1)Aiming at the model mismatch problem of SAR moving target imaging,we have established a hybrid SAR/ISAR imaging model,and then derive echo signals' mathematical expression.Next,from three aspects,the effects of target motion characteristics on imaging are described in detail.Moreover,simulation experiments verify the accuracy of the obtained conclusions.(2)A real-time parameter estimation algorithm based on Wigner-Ville distribution(WVD)slice and fractional Fourier transform(Fr FT)is proposed in this paper.The superiority of the presented method is especially noticeable for SAR real data processing and it provides a novel and effective way for SAR real-time estimation.(3)According to its application,non-linear motion trajectory SAR imaging is divided into avoidance trajectory SAR imaging and subduction decline SAR imaging.By modifying some of the phase factors,the Range-Doppler algorithm can be used to realize avoidance trajectory SAR imaging.Then,on the basis of modifing the traditional slant range expression,we derive a subduction descent SAR imaging algorithm.Next,the imaging algorithm based on azimuth nonlinear scaling is analyzed in details.The feasibility and effectiveness of above three algorithms are verified by simulation experiments.(4)The feasibility of ship target imaging by hybrid SAR/ISAR imaging algorithm is detailed discussed.Then,severval ship targets' high-resolution imaging results with better focus effect are obtained.What's more,in order to expand its applicable range,a no-linear trajectory hybrid SAR/ISAR imaging algorithm is proposed in this paper,which confirmed its strong engineering application value in the SAR moving target imaging field.