A New Slow PRI Variation Scheme for Multichannel SAR High-Resolution Wide-Swath Imaging

In the design of spacebome synthetic aperture radar (SAR) imaging systems, high-resolution and wide swath are inherently incompatible requirements. As shown by extensive research in this field, advanced instrument modes and architectures employing multiple receive channels in elevation and/or azimuth represent a feasible solution for this conflict. This paper addresses a novel high-resolution wide-swath SAR imaging mode that uses multiple elevation and azimuth beams in combination with a scheme of slow variation of the pulse repetition interval (PRI). It is shown that this new mode enables a high-performance 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 with a diameter of 12 m. In addition, 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.