A Novel Digital Beam-Forming Concept for Spaceborne Reflector SAR Systems

The trend in the conception of future spaceborne radar remote sensing is towards the use of digital beam-forming techniques. These systems will comprise multiple digital channels, where the analog-to-digital converter is moved closer to the antenna. This dispenses the need for analog beam steering and by this the use of transmit/receive modules for phase and amplitude control. Digital beam-forming will enable Synthetic Aperture Radar (SAR) which overcomes the coverage and resolution limitations applicable to state-of-the-art systems. Moreover, new antenna architectures, such as reflectors, already implemented in communication satellites, are being reconsidered for SAR applications. This paper introduces a new digital beam-forming radar concept based on the combination of a reflector with a digital feed array. For a system example the SAR performance is estimated. Finally a novel digital signal processing approach, exploiting the signal properties of the transmitted waveform, is presented