Research On Three Dimensional Synthetic Aperture Radar Imaging Technology With Frequency Diverse Array

The linear array three-dimensional synthetic aperture radar(SAR)can realize the observation of richer information in the scene,which has become one of the hotspots in the field of radar research in recent years.Each element of the traditional three-dimensional SAR emits wideband signals which brings the problems of nonlinearity of wideband signals and the inability to effectively separate wideband signals at the receiving.Frequency diverse array(FDA)three-dimensional SAR elements send single frequency signals with difference frequency which gets rid of the limitation of traditional linear array three-dimensional SAR transmitting wideband signals,and has high application prospects and research significance.The FDA three-dimensional SAR with random frequency offeset causes the problems of large number of array elements,large system volume,low array element utilization,and difficulty in hardware implementation.To overcome this problem,the multiple-input multiple-output(MIMO)sparse array technology is combined with the FDA three-dimensional SAR imaging.Research on the MIMO-FDA three-dimensional SAR imaging technology.The main research contents are as follows:1.Introduced the main theoretical basis of the frequency diverse array,the linear array three-dimensional SAR and MIMO.First,the signal model of the FDA and the spot beam are described,and the characteristics of the FDA are analyzed.Then the linear array three-dimensional SAR and its combination technology with the FDA are introduced,and finally introduces the principle of MIMO technology to realize the virtual array elements.2.Aiming at the problem of too many elements in the FDA three-dimensional SAR,the MIMO sparse array is introduced into FDA three-dimensional SAR,the MIMO-FDA three-dimensional SAR imaging model is established.The back projection(BP)algorithm and compressed sensing(CS)imaging algorithm under the new model are studied,the virtual array and its frequency d istribution under two array configurations are analyzed,and the influence of different frequency offsets on MIMO-FDA three-dimensional SAR imaging is studied.The simulation results show that both the array and the observation are linear frequency offset of the MIMO-FDA three-dimensional SAR can image without unambigous,and the introduction of nonlinear frequency offset can improve the imaging effect.3.Research and analysis of random frequency offset MIMO-FDA 3D SAR imaging method and performance.Aiming at the hardware cost problem caused by the fully random frequency offset while achieving the ideal performance,a "fixed + random" MIMO-FDA three-dimensional SAR imaging method is proposed.Compared with the fully random MIMO-FDA three-dimensional SAR,the frequency offset of this method is no longer randomly selected at different observation points in the along-track,but remains fixed.This method can achieve target imaging and also reduces the requirements for hardware costs.Finally,the imaging resolution is further analyzed from the perspective of synthetic aperture,and simulation verification and comparison are performed.