LAUSR

Digital beamforming (DBF) with scan-on-receive (SCORE) is a state-of-the-art technique for high-resolution and wide-swath observation in synthetic aperture radar (SAR) imaging. However, this technique has a problem with frequency dispersion. Most existing DBF methods treat the frequency as a constant, and little work has been devoted to the analysis of frequency dispersion. To address this shortcoming, this letter analyzes the dispersion effect using the raw data of two digital beamforming synthetic aperture radars (DBF-SARs). Moreover, this letter demonstrates in practice for the first time the effectiveness of the digital scalloped beamforming (DSBF), one of the candidates for solving the frequency dispersion problem in SCORE DBF, using the X-band sixteen-channel DBF-SAR and the C-band four-channel DBF-SAR. The analyses of the impulse response width extension and the signal-to-noise ratio (SNR) improvement are presented in detail to show the performance of the frequency dispersion compensation. The results show that the DSBF is effective in compensating for the frequency dispersion in the DBF technique. With DSBF, a higher SNR improvement can be obtained in DBF-SARs.