A Novel High-Resolution Wide-Swath SAR Imaging Mode Employing Multichannel Slow PRI Variation

Inhalt:
High resolution and wide swath imaging are conflicting requirements in the design of spaceborne synthetic aperture radar (SAR) systems. Several studies have shown that this fundamental conflict can be resolved by advanced instrument modes and architectures employing multiple receive channels in elevation and/or azimuth. This paper introduces a new high-resolution wide-swath SAR imaging mode that uses multiple elevation and azimuth beams in combination with a slow variation of the pulse repetition interval (PRI). It is shown that this new mode enables the development of a highly performant SAR system with a rather compact antenna. As an example, the design of an L-band system is presented that is capable of imaging a 400 km wide swath with an azimuth resolution of 5 m in single polarization. A detailed analysis reveals that an excellent performance is achieved by combining a digital feed with 3 azimuth and 30 elevation channels using an unfurlable reflector that spans a diameter of 12 m. If compared to the staggered SAR mode of Tandem-L, which will employ a reflector with a diameter of 15 m, the required antenna aperture is reduced in the new mode by more than 35 %. Moreover, the same architecture enables the operation in a multichannel staggered SAR mode, which allows for the mapping of a 200 km wide swath with an even higher azimuth resolution of less than 2.5 m in a fully polarimetric mode.