Improved Digital Beam-Forming Approach With Scaling Function For Range Multi-Channel Synthetic Aperture Radar System

For the next generation of space-borne synthetic aperture radar (SAR) remote sensing satellites, high resolution and wide coverage are important goals. Digital beam forming (DBF) with multiple channels in elevation (e.g.SCan-On-REceive) is a promising candidate to cover ultra-wide swaths. This scheme could increase the receiver gain and signal-to-noise ratio so as to enhance the performance of an SAR system. As the swath width expanding, ultra-wide beam in range for illuminated scene is needed. However, in this case, the signals received by different channels cannot always be co-registered during the receiving window before combining them due to the imaging geometry of the DBF-SAR system. The relative migration would cause gain loss while performing DBF. In this study, according to the geometric relationship among the receiving channels, the migration of signal received by each elevation channel is analysed and the explicit expressions are derived in detail. Then, an improved DBF approach based on scaling function is proposed for registering the received signals of different channels and combining them. This proposed process can be implemented with better performance than other approach. Finally, the simulation results validate this improved method.