Abstract: The paper deals with a calibration method for quasi-broadsie side-looking mode SAR imaging with a small squint angle.First, the method adopts the broadside side-looking mode subaperture spotlighting algorithm to image the real data of the quasi-broadside side-looking mode SAR, and then based on the obtained image the small squint angle is estimated.Finally, the calibrated squint side-looking mode subaperture spotlighting algorithm is employed to obtain the final image.The paper also places emphasis on a novel method called the phase alignment algorithm for subaperture reference signals.The algorithm adjusts phases of respective subaperture reference signals in order to make them in phase and constructs a new spotlighting window function for SAR imaging.The theoretical analysis shows that under the condition of the same sample data, the novel method can increase the SAR scene area in azimuth dimension.The methods are verified by the results of computer simulation.

Key words: stripmap synthetic aperture radar, calibration, squint, reference signal