Based on Two-Step processing approach and Chirp Scaling algorithm

a Deramp Chirp Scaling (DCS) algorithm for high-resolution spaceborne spotlight synthetic aperture radar (SAR) imaging was presented.The algorithm combined the advantages of SPECAN algorithm and Chirp Scaling algorithm.Firstly

the azimuthal coarse focusing was achieved via a deramp processing with constant Doppler rate

and the azimuthal spectral folding phenomenon

which was typical for spaceborne spotlight SAR

was overcome.Secondly

the precise range focusing was achieved by Chirp Scaling principle

and the residual azimuth phase error was compensated

so the refined azimuthal focusing was acquired.Based on the squinted equivalent range model that was fitter for spaceborne geometrical relation than the broadside range model

the complete derivation of the algorithm was presented and the realizing approach was given.The whole algorithm could be implemented by complex multiplication and fast Fourier transform (FFT) without any interpolation of the data.The algorithm was suitable for wide range swath high-resolution spaceborne spotlight SAR imaging.Finally

the computer simulation showed the validity of the algorithm.