Study Of Bistatic Synthetic Aperture Radar Imaging

The difficulty in the derivation of bistatic SAR imaging algorithms lies in the bistatic point target reference spectrum, particularly in the analytic forms. The method of stationary phase can not be used to derive this spectrum due to the double square root terms in the bistatic range history. Hence, the derivation of bistatic point target reference spectrum has received many research interests in the world's radar community. To my knowledge, the exsiting solutions that have received high interests include the DMO method derived from the seismic data processing, the GBF formula for constant-offset bistatic configurations, LBF and the analytic MSR spectrum both for general configurations. Actually, these solutions should related to each other from the point view of physics. First, some aspects of bistatic radar were discussed, including its worldwide history, signal property and its Doppler characteristics. The link between the DMO and reduced GBF was given, which fills the gap in the Neo's summary paper. The misleading addressment in the original DMO publication was also cleared. Secondly, We overviewed these exsiting methods, and gave numerical examples of focusing simulated bistatic data using various bistatic point target reference spectra. Besides, we presented a modified point target reference spectrum for spaceborne SAR focusing with proof numerical simulations. Finally, the original LBF was extended to process the spaceborne bistatic data collected by two radars mounted on a high-orbited and a low-orbited satellites respectively, and also the data supposed to be from space-surface hybrid bistatic compains. This idea of weighting LBF was developed independedntly by two researchers in the same group. A bistatic range Doppler algorithm was given to focus a SAR scene by using preprocessing of bistatic deformation phase. A brief summary was given by items as follows,1,The link between the DMO and reduced GBF, when they are applied to the tandem bistatic configuration, was derived. Besides, the misleading addressment in the original publication on DMO was cleared. The DMO method was re-derived from the pointview of radar signal processing.2,Four bistatic point target reference spectra, DMO, GBF, LBF and MSR, were overviewed, and numerical examples of focusing simulated bistatic data using various bistatic point target reference spectra were given. This part serves as a reference in the future development of bistatic SAR processor. 3,A MSR-based spaceborne point target reference spectrum was proposed as a new high order frequency domain approach. Its accuracy was examined by a computer simulation. In addition, some aspects on spaceborne SAR models and signal property are overviewed in this part.4,The original LBF was extended by using a weighting operation in the Fourier integral. It removed the error due to the identical segment of transmitting and receiving phase histories. It can be used to process the spaceborne bistatic data collected by two radars mounted on a high-orbited and a low-orbited satellites respectively, and also the data supposed to be from space-surface hybrid bistatic compains.. A bistatic range Doppler algorithm was given to focus a SAR scene by using preprocessing of bistatic deformation phase.