The effect of spaceborne spotlight SAR antenna beam pointing steered on image quality

In the condition of beam pointing steered spaceborne spotlight synthetic aperture radar (SAR) antenna model and imaging model are found. The math analysis confirms that beam pointing steered results in echo amplitude being modulated and causes infinite pairs of echoes. So beam pointing steered may deteriorate image quality. Besides, based on the analyses of tradeoff relation of beam pointing steered ratio, spot area azimuth width and image dynamic extension, the fundamental principle of designing beam pointing steered ratio is presented. Finally, point target simulation is given and simulation result tests the validity of theoretical analysis.