中轨SAR海面运动舰船回波建模研究

中轨SAR具有宽测绘带及重访时间短的优势，是低轨SAR与高轨SAR的重要补充。然而，相对于低轨SAR，中轨SAR具有合成孔径时间长，轨道特性复杂等特点，常规斜距模型不适用于中轨SAR。考虑了回波非"停-走-停"的情况，结合轨道及运动舰船特点，对中轨SAR舰船目标斜距模型进行定量化分析。得到舰船在静止、匀速运动、加速运动时四阶斜距模型能够满足成像要求，当受海浪影响时四阶斜距模型将失效的结论。最后实现中轨SAR海面舰船回波精确建模。

Echo Modeling of Moving Ship Target for MEO SAR

Medium-orbit SAR (MEO SAR) is an important complement to low-orbit SAR and geosynchronous orbit SAR because of its advantages of wide swath and short revisit time. However, compared with low-orbit SAR, MEO SAR has the characteristics of long synthetic aperture time, complex orbital characteristics. Conventional echo model is not suitable for the imaging of moving targets in MEO SAR. In this paper, the slant-range models of MEO SAR are quantitatively analyzed. It is concluded that the fourth-order slant-range model can meet the imaging requirements when the ship is in the case of static, uniform motion and acceleration. But it will be invalid when the ship is affected by ocean waves. Finally, the accurate echo model of medium-orbit SAR is realized.