A new fourth-order processing algorithm for spaceborne SAR

A new fourth-order signal aperture radar (SAR) processing algorithm has been developed for a general satellite-Earth relative motion. The two-dimensional exact transfer function (ETF) is calculated and range-variant phase corrections have been calculated in order to process many azimuth lines per block. The ETF together with the phase corrections has been called the fourth-order EETF (extended ETF). It is also shown that a fourth-order EETF is necessary to process high quality images from spaceborne SAR with long integration times with spatial resolution around 1 m. The algorithm is fast and is anticipated to have good phase preservation properties.