Demonstration of Intermediate Frequency Digital Beamforming With X-Band and C-Band DBF-SARs

High-resolution wide swath (HRWS) imaging has become a research hotspot in the field of synthetic aperture radars (SARs) in recent years. Digital beamforming (DBF) denotes a powerful technique for obtaining the HRWS images. The DBF can be implemented in a spaceborne SAR in real time but at the cost of massive digital resources. To solve this problem, an intermediate frequency (IF) DBF real-time processing architecture has been proposed, but it has never been validated in practice. In this letter, the X-band 16-channel DBF-SAR and the C-band four-channel DBF-SAR are used to demonstrate the effectiveness of the IFDBF scheme in practice for the first time. The performance of the IFDBF scheme is verified by the detailed analysis of the signal-to-noise ratio (SNR) improvement and system complexity. The result shows that the IFDBF scheme can achieve the same SNR improvement as the DBF scheme. Moreover, by applying the IFDBF scheme, a spaceborne SAR can save more digital resources in real-time processing.