Digital beam forming of azimuth direction for SAR image processing

For SAR (Synthetic Aperture Radar) system, the high resolution (range/azimuth) and wide swath are required constantly. It is challenge to achieve both high azimuth resolution and wide swath imaging for spaceborne SAR system because it poses contradicting requirements for pulse repetition frequency. The technique of the multiple receive apertures and digital beam forming is utilized to overcome the difficulty. The reconstruction process for the independent receive channels has been developed to process the multiple received data [4]. The PRF should be selected carefully on this processing in order to keep S/N (Signal to Noise ratio), though it is difficult to control the PRF flexibly in orbit. The digital beam forming processing for azimuth direction (Azimuth DBF) is proposed instead of the reconstruction processing, which PRF can be selected flexibly in this processing. Azimuth DBF was applied to the experimental data required by airborne SAR system and it seems to be successfully processed. In this paper, the concept of Azimuth DBF and the evaluation result are described.