Imaging Method Research For Bistatic Forward-Looking SAR Mounted On High-Speed Maneuvering Platform

With receiver mounted on high-speed maneuvering platform(HMP)and transmitter mounted on another independent platform,HMP bistatic forward-looking synthetic aperture radar(HMP-BFSAR)can achieve the two-dimensional(2-D)imaging of the forward-looking terrain,which breaks through the inherent limitation of traditional monostatic SAR.HMP-BFSAR is of great research value and application value for many fields such as precise guidance and landing navigation.Imaging method plays a key role in the high-resolution image formation for HMPBFSAR.In this dissertation,researches and simulations on accurate echo modeling,spatial resolution modeling and efficient imaging algorithm of HMP-BFSAR are carried out.The main innovations are as follows.1.A BFSAR quadratic-maneuver echo model without stop-and-go assumption is proposed.By introducing the quadratic term of the receiving platform's maneuver during pulse propagation,the proposed model significantly improves the precision of the echo model of HMP-BFSAR,hence lays theoretical foundations for the spatial resolution modeling and efficient imaging algorithm designing.2.A quadratic-Doppler resolution model is proposed.By representing the influence of platforms' acceleration on the Doppler ground resolution with the quadratic Doppler phase of the ambiguity function,the proposed model solves the problem of precise measurement of the resolution of HMP-BFSAR.3.A support-region-normalization(SRN)affine transform polar format imaging algorithm is proposed.Firstly,the utilizing efficiency of the wavenumber spectrum is improved using SRN affine transform.Then,the wavefront-curvature-induced defocusing of the marginal targets in large scene are solved by space-variant-refocus filtering.The proposed algorithm can achieve large-scene image formation of HMPBFSAR with moving illuminator efficiently and precisely.4.A time-delay look-angle coordinate space imaging algorithm is proposed.By transforming the echo data into the time-delay look-angle coordinate space and constructing the corresponding range model according to the illuminator's stationary property,the time-frequency coupling in the time-delay phase of the echo can be eliminated.The proposed algorithm can improve the image formation efficiency of HMPBFSAR with stationary illuminator.The models and algorithms mentioned above have been verified by simulations.The results show that the proposed models and algorithms can effectively solve the main problems in HMP-BFSAR imaging,and realize the image formation of HMP-BFSAR efficiently and accurately.