A new subaperture approach to high squint SAR processing

In this paper, a high squint subaperture (HSS) algorithm was developed from the perspective of a stripmap synthetic aperture radar (SAR) system and ha s the ability to focus SAR data at extremely high squint angle of 55 degree s with less than 1.27% mainlobe expansion or even higher squint angles if l arger mainlobe expansion can be tolerated. The unique characteristic of thi s algorithm is that the subapertures are formed by multiplying the received signal with a set of overlapped complex conjugated reference signals where the chirp rate varies in the azimuth direction. This is done to solve the range focus problem that arises after the azimuth input signal undergoes th e range walk removal procedure. As the HSS algorithm only involves short fa st Fourier transforms (FFTs) and avoids interpolation, it is computationall y efficient and allows for small data buffers and facilitates hardware real -time implementation. The distinct feature of this algorithm is its simplic ity of implementation, which is vital in real time processing and motion co mpensation when the squint angle may be changing continuously.