To overcome the deterioration of azimuth resolution caused by errors of monopulse response curve (MRC) in practical processing

this paper proposes an autofocusing algorithm for monopulse imaging technique.By applying iterative steps

this algorithm automatically extracts the echo signals of isolated strong scatterers from the received data

and employs them to accurately estimate the actual MRC.The estimated curve is then used in the procedure of monopulse imaging to autofocus the image in azimuth.As is verified by simulation and experimental results

this algorithm can effectivelyreduce the impact of MRC errors on monopulse imaging and is robust to most of the ground scenes

making it feasible in practical processing.