Research On Image Formation For The Forword-looking Bistatic SAR

As a special concept bistatic SAR which separates the transmitter and receiver,bistatic forward-looking SAR (FL-BiSAR) leads the beam of the receiver pointing thefront scene of the radar, therefore, FL-BiSAR system not only propose some advantages,such as its flexibilities, good imperceptibility, rich information about objects and highanti-interference ability, but also obtain the imaging and detecting capability about thefront area of radar. Therefore, it has more wide applications. However, due to the specialconfiguration, it leads the present algorithms losing effectiveness. The image algorithmsin frequency domain are studied for FL-BiSAR in this dissertation. The main contentsand innovations are demonstrated as follow:1. the BiSAR imaging’s fundamental theory is Introduced. Firstly, the echo modelof BiSAR configuration is analyzed. Based on the time-domain features of the rangehistory, its characteristic is discussed, Then with the gradient method, introduce therange history and Doppler resolution. Finally, study the parameters and time-domainimage model in FL-BiSAR system.2. Image algorithms based on the2D-PSP spectrum model are proposed. From thesimulations, MSR spectrum model and2D-PSP model are suitable for the FL-BiSARconfiguration, while the ω-k algorithm based on MSR model is also suitable for theFL-BiSAR; Based on the2D-PSP model, a novel ω-k algorithm is raised. Contrastedwith the ω-k algorithm based on MSR model, when the difference of the platform’smovement is small, the proposed algorithm is more accurate.3. A spaceborne/airborne FL-BiSAR(SAFL-BiSAR) image algorithm based on theAP model is modified. Firstly, From the simulations, the AP spectrum model applies tothe SAFL-BiSAR configuration. Secondly, due to the present algorithms based on theAP model losing effectiveness, A new algorithm is put forward. It can compensate hightime frequency items and get exact imaging result on the SAFL-BiSAR echo.4. a concise and accurate2-D equi-monostatic spectrum expression(2DEMSE) andits algorithms are proposed. Firstly, through to the analysis about the time-domainfeatures of the FL-BiSAR range history, a concise2-D spectrum expression is introduced, which is obtained by using the curve fitting and POSP theorem. Secondly,based on the spectrum, algorithms from the Taylor expansion of azimuth frequency orspace-domain are proposed. With the simulations, the algorithms are suitable forFL-BiSAR.5. a high accurate2-D spectrum expression and its algorithms are proposed.Contraposing2-D equi-monostatic spectrum, a more accurate2D spectrum isintroduced, and the algorithm based on it is proposed which can get the better imagingresult for the echo of airborne/airborne FL-BiSAR.