First Demonstration of Spaceborne SAR Terrain Matching Curved Imaging with LJ2-01 Satellite

The swath of the conventional spaceborne synthetic aperture radar (SAR) is parallel-to-orbit, making it inefficient to observe long curved terrain, such as coastlines, railways, and so on. Imaging long curved terrains with the terrain matching (TM) curved swath is a promising technique for efficient data acquisition. The key feature is the employment of a long curved swath matching with the orientations of the long curved terrains. This article reports the first demonstration of the spaceborne SAR TM curved imaging with the LJ2-01 satellite. A TM curved swath of 161.7 km is imaged with an azimuth resolution of 0.6 m. The main technical contributions are as follows. First, a new electrical-mechanical-combined beam control method is proposed to achieve uniform azimuth resolution. Second, a new nonuniform pulse repetition frequency (PRF) sequence is used to mitigate the data loss caused by the violent spatial variation of the slant range. Third, a new swath-adaptive subaperture time-domain imaging algorithm is proposed for efficient TM curved swath imaging. These innovations contribute to successful data acquisition and imaging of the spaceborne SAR TM curved imaging with the LJ2-01 satellite.