星载干涉合成孔径雷达高度计波束指向优化设计新方法

基于干涉合成孔径雷达(InSAR)体制的星载高度计能实现高分辨率、宽幅、高精度海面高程测量。传统合成孔径雷达(SAR)系统波束指向设计方法以SAR图像近远端噪声等效后向散射系数差异最小化为优化目标,星载InSAR高度计对海入射角小,如采用传统波束指向设计方法将面临系统近端测高性能优于远端等问题。为使远端测高性能满足应用精度指标要求,系统需提高雷达发射功率或增大雷达天线尺寸,这对卫星系统提出了较高的要求。提出了面向测高应用的星载InSAR高度计波束中心指向设计新方法。该方法通过调整雷达波束中心指向实现全场景测高性能最优化,可有效降低传统设计方法中SAR载荷对发射功率等卫星指标的要求,对未来我国发展InSAR体制海面高度计系统设计具有重要的指导意义。仿真分析结果验证了新方法相对于传统设计方法的优越性。

A Novel Beam-Steering Method for Spaceborne Interferometric Synthetic Aperture Radar Altimeter

The spaceborne altimeter based on interferometric synthetic aperture radar (InSAR) can achieve high-resolution, wide-swath and high-accuracy height measurement of sea surface. The beam steering of SAR systems in orbit is designed to access SAR images with the same noise equivalent sigma zero (NESZ) for near-range and far-range observation areas. However, for InSAR altimeters, the conventional method will result in the height accuracy of near-range areas much higher than the far-range ones. To achieve the required height accuracy in far-range areas, SAR systems have to improve the transmission power or increase the size of antenna, which improves the complexity in system designation. In this paper, a novel beam-steering method for spaceborne InSAR altimeters is proposed. The beam-steering angle is optimized according to the height accuracy in the whole scene. This work can effectively contribute to the development of InSAR altimeters with reduced power requirements in China. The performance of the proposed method over the conventional method is validated by simulation results.