Research On The Application Of FDA In SAR Imaging Technology

The use of Frequency Diverse Array(FDA)transmiting waveforms and coherent receivers in Synthetic Aperture Radar(SAR)imaging systems can effectively utilize the advantages of frequency diversity to improve the range and azimuth resolution of SAR imaging,which has becomed the main research direction for FDA-SAR imaging.Therefore,this thesis combines the advantages of FDA and SAR radar to prorose a new imaging mode,and studys the beamforming and imaging algorithm for the FDA-SAR.The following aspects of the work are mainly completed in this thesis:(1)We researched the basic concepts and principles of FDA radar.The FDA's array structure and transmit signal model are formulated.The linear array of conventional transmit arrays can transmit linearly or logarithmically increasing transmit waveforms with small frequency offsets.The FDA beam pattern also depends on the time,angle,and distance.(2)SAR imaging algorithm is derived and point target simulation experiments are carried out.The working mode of SAR and the reason of range-azimuth coupling are introduced.The SAR signal model is established.Firstly,the classical range-doppler(R-D)algorithm is introduced.Then,the keystone algorithm of strabismus SAR is introduced,and the geometric model and imaging algorithm flow are established.(3)We researched the method of using FDA technology for SAR imaging and found that it can significantly improve imaging performance.In wide-swath imaging,FDA-generated distance-related phase shifts can be used to extract signals from blocks at different distances.Then we utilize FDA range and azimuth-dependent beam patterns to solve the problem of azimuth blur in SAR imaging.The simulation results verify that FDA-SAR can effectively improve the imaging performance.