ON THE USE OF TIME-DOMAIN SAR FOCUSING IN SPACEBORNE SAR MISSIONS

This paper discusses the relevance and use of efficient focusing in the time domain in spaceborne SAR. With the increasing number of space-variant corrections required by higher resolution and wide swath observations, the efficiency of SAR focusing algorithms in the Fourier domain drops significantly. The main sources of space variance to be faced in future spaceborne SAR missions and their implications on the complexity of the focusing process are discussed. The paper also presents a direct comparison between time-domain and frequency-domain approaches, providing an estimate of the computational burden of a fast-factorized backprojection algorithm compared to a sophisticated numerical omega k, identifying the operation areas where the the former may show an efficiency advantage.