Bistatic Sar Spatial Resolution Characteristics Of The Study

Bistatic SAR is the synthetic aperture radar whose transmitter and receiver are located on separated platforms. It can acquire non-backscatter information, and the quite passive receiver is more difficult to be detected and jammed. Bistatic SAR is becoming one of the hotspots in the field of radar imagery in recent years.Started by disgussion of Bistatic Radar's Target Character, this paper first compared RCS (Radar Cross Section) of Bistatic SAR with RCS of Mono-static SAR. The RCS of Bistatic SAR is divided into tree different areas according to Bistitic angle. Then Bistatic Radar Function is analyzed and the echoed signal models are introduced according to the reseach methods on which Mono-Static SAR depend.A geometry model for general flight configuration and its corresponding echoed signal model are established. Based on the geometry model, range history and Doppler charactors are disgussed in detail. Unlike Monostatic SAR, the Doppler history of Bistatic SAR varies in different position of the point target which led to the difficulties of fast imaging algorithms. Considering a concrete configuration of Bistatic SAR, the depth of focus along a special direction of Bistatic SAR is deduced in this dissertation. The simulations on the depth of focus are done by RD imaging algorithm under the condition of transmitter and receiver moving parallelly, and by BP imaging algorithm under the condition of transmitter and receiver moving arbitrarily. The results show that the depth of focus of Bistatic SAR is much smaller than that of Monostatic SAR. The depth of focus of Bistatic SAR degrades with the increase of angle between the moving directions of transmitter and receiver, and the squint angle of transmitter or receiver.In this dissertation, the spatial resolutions at different directions of bistatic SAR have been derived from the ambiguity function. Compared with monostatic SAR, Bistatic SAR's resolutions of a fixed point target is varying with respect to the slow time, since bistatic SAR system is space-variant. Constraints for the assumption of space-invariant bistatic topology are put forward. Moreover, under the assumption of invariance, the change of resolutions at different point in the image scene is taken into account, and the direction in the scene along which the range resolution changes the fastest is given. This analysis can be used for the problem of how to select the optimum patch of imaging when the position of the platforms is fixed.The author has specified six key parameters that affect resolutions directly and analyzed the way how they influence on the resolutions. They are as follows: the angle between velocities of the platforms, the ratio of module of velocity, the angle between the angular speeds of the platforms, the ratio of slants of the platforms, the squint angle of the platforms. Through these researches, some conclusion is obtained: some patches where resolution ability degrades greatly can not satisfy the demands of high-resolution. Geometry parameters are very important for the resolution of Bistatic SAR. These analyses can contribute the the study of topology-designing on Bistatic SAR.