When multiple targets in formation are in the observation region

the return signals from these targets may be overlapped both in the range and Doppler domain.Thus

it is difficult to separate these targets from each other

and each individual target cannot be clearly imaged.A new implementation method of ISAR imaging is proposed for multiple targets in formation.After radial acceleration compensation and Keystone transformation are performed

range alignment is accomplished for all moving targets.When multiple targets are moving smoothly

the Doppler variation of subechoes from scatterers can be approximated as a first-order polynomial.Therefore

the modified Chirp-Fourier transform combined with the CLEAN technique is applied to each range cell to obtain the cross-range profiles of multiple targets simultaneously.The imaging results obtained by using simulated data show the effectiveness of the proposed method.