High‐Precision Airborne Circular SAR Imaging Method Based on Sub‐Aperture Autofocusing Combined With Terrain Undulation Error Compensation

Le résumé fourni par la source

ABSTRACT Airborne circular synthetic aperture radar (CSAR) has the ability of multiangle observation and high‐resolution imaging in remote sensing applications, but its imaging performance is often degraded by the platform motion error and terrain undulation error. To address this issue, a high‐precision airborne CSAR imaging method based on the sub‐aperture autofocusing combined with the terrain undulation error compensation is proposed. First, the scene digital elevation model (DEM) data are adopted to set the CSAR imaging grid, which can compensate the terrain undulation error. Besides, the full aperture echo data are subjected to the range compression processing, and then the backprojection (BP) algorithm is used to process the sub‐aperture data and obtain the preliminary sub‐aperture image. Moreover, multiple iterations of the autofocusing processing are performed on the sub‐aperture images to obtain the well‐focused sub‐aperture images. Finally, the focused sub‐aperture images are incoherently accumulated to obtain the high‐precision full‐aperture CSAR image. Experimental results based on the point target simulation data, CVDomes electromagnetic simulation data and Gotcha measured data demonstrate that the proposed method can effectively mitigate the platform motion error and terrain undulation error, which can improve the focusing performance of the airborne CSAR imaging in remote sensing applications.

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