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双站合成孔径雷达(SAR)前视成像有着很多的潜在应用,比如在能见度很低的天气实现飞机的导航和盲降,提高飞机飞行的安全度等.然而实现双站SAR前视成像的难点在于其距离历程的双根式性,直接采用驻定相位原理对其分解将得到复杂的解析式,从而后续算法的推导变得困难.现有的双曲等效法可以将双根式距离历程等效为单根式,但由于该方法为距离历程的二阶近似,当用于双站SAR前视成像时,由于其较大的前视角,未完全等效的距离历程高次项造成的误差已经超出可以接受的范围.针对以上问题,本文首先提出了一种改进的双曲等效法,该方法通过引入新的补偿变量来提高距离历程的等效精度;然后在此基础上推导回波信号的二维频谱解析式,并给出了一种适用于双站SAR前视成像的距离多普勒算法;最后通过仿真实验,将原双曲等效法与改进方法的等效误差以及成像结果做对比,验证了本文算法的有效性和优越性.
Bistatic Synthetic Aperture Radar (SAR) foresight imaging has many potential applications, such as the navigation and blind landing of aircraft in the low visibility, the safety of the flight, etc. However, the difficulty of the forward bi-station SAR imaging Is based on the bilinear nature of its distance history and directly decomposes by using the stationary phase principle to obtain complex analytical expressions, so that the derivation of subsequent algorithms becomes difficult. The existing hyperbolic equivalent method can make the double root distance process equivalent to However, due to the second-order approximation of the distance history, this method, when used in bi-station forward-looking SAR imaging, has exceeded the upper-order term of incompletely equivalent distance history due to its large forward-looking angle, This paper first proposes an improved hyperbolic equivalence method which improves the equivalent accuracy of distance history by introducing a new compensation variable. Based on this, the two-dimensional Spectral analytic formula and a distance Doppler algorithm suitable for bistatic SAR forward-looking imaging. Finally, through the simulation experiments, the equivalent errors between the original hyperbolic equivalent method and the improved method and the imaging The results are compared to verify the effectiveness and superiority of the proposed algorithm.