Impact Analysis and Suppression of APC Deviation on High-Resolution Spaceborne SAR Imaging

Abstract

With the widespread application of high-resolution spaceborne synthetic aperture radar (SAR), high demands are placed on the accuracy of measured information. The position error between the antenna phase center (APC) and the position measurement elements, called APC deviation, can affect high-resolution imaging if ignored. This article establishes a unified analytical model for APC deviation in high-resolution spaceborne SAR under attitude maneuvering and electronic scanning modes. Based on this model, the slant range history error and the corresponding phase error are derived, thereby clarifying the distinct APC deviation mechanisms under the two beam control methods. The non-negligible thresholds of APC deviation are then quantified with respect to wavelength, azimuth resolution, and deviation magnitude, and the spatially variant characteristics of the phase error in both range and azimuth are analyzed. On this basis, a correction method based on echo for raw echoes and a compensation method based on image for SLC data are developed to suppress the impact of APC deviation. Finally, simulation and real data experiments confirm the effectiveness of the proposed analysis and correction methods. Validation using real data from SuperView Neo-2 satellite with a resolution of up to 0.18 m shows an approximately 10% improvement in the resolution of typical corner reflector targets, as well as an approximately 35% decrease in the image entropy of azimuth edge landforms. The results demonstrate that considering the impact of APC deviation is of reference value for the design and optimization of existing spaceborne SAR systems.