Improved DBF SAR imaging on receive with phase compensation

Abstract

Digital beamforming (DBF) synthetic aperture radar (SAR) on receive in elevation is a promising candidate to realize the demanding requirement of high resolution and wide swath (HRWS) in remote sensing. But this technique suffers from a degraded imaging performance due to the incoherence between the received signals from different subchannels. When SAR sensor transmits a long pulse, the output of DBF network will be seriously modulated within recorded time window. The amplitude modulation of beamformer output will introduce severe bandwidth loss, thus resulting in a decreased resolution and imaging magnitude. In order to overcome the deficiency mentioned above, this paper puts forward an improved phase compensation method for range DBF SAR system. Through phase corrections of the received signals from all the subarrays, the echoes of multiple channels can be coherently synthesized. Consequently, the proposed method can eliminate the amplitude modulation effect of beamformer, and subsequent imaging quality can be significantly improved. Both numerical analysis and experimental results testified the favourable improvements of this proposed strategy.