Performance Analysis and System Design in GEO-LEO Bistatic SAR

The geosynchronous-low-Earth-orbit bistatic synthetic aperture radar (GEO-LEO BiSAR) adopts the transceiver split system form, in which GEO SAR serves as the illuminator and LEO SAR serves as the receiver. GEO-LEO BiSAR can obtain abundant target scattering information, can realize large width imaging and reduce the receiver cost. Three parameters are selected as measurement indicators to comprehensively evaluate system performance and provide system design guidance. The spatial resolution can measure the imaging performance, the radiation resolution is the ability to distinguish the objects scattering characteristics, and the beam coverage area represents the system observation ability. They are all key parameters and are closely related to the BiSAR configuration. In this article, we use the generalized ambiguity function and integral equation model to derive the BiSAR spatial and radiation resolution expressions, and the beam coverage area calculation method is derived through geometric knowledge. These three parameters are modeled as objective functions for the system design of the multiobjective optimization problem, in which multiobjective evolutionary algorithm based on decomposition and differential evolution is used to solve the receiver orbital element. We can optimize these three parameters jointly considering their values or optimize the resolution (spatial and radiation resolution) and coverage area in sequence. Finally, the analysis correctness is verified by simulation experiments. The proposed system design method comprehensively considers the ability of observation, resolution and recognition, and can reasonably select joint or sequential optimization schemes according to the system capability requirements to guide the receiver orbital element selection.