Broadband digital beamforming based on fractional delay in SAR systems

Synthetic Aperture Radar (SAR) system can achieve both high azimuth resolution and wide swath by applying digital beamforming (DBF) technique in its receiving terminal. This DBF-SAR system requires broadband digital beamforming on the receiving array. In broadband beamforming, phase-shift method causes beam pointing deviation and mainlobe widening. In this paper, digital true time delay filters were used to compensate the phase deviation at the pointing bearing. Under interference, a structure composes of digital time-delay filters and tapped delay line (TDL) was built to implement adaptive broadband beamforming. It is showed by simulation that this method is effective in both broadband beamforming and broadband interference suppression, which improves the SINR of received signals.