Spaceborne Interferometric and Multistatic SAR Systems

This chapter analyses spaceborne multistatic imaging radar systems employing two or more receiver antennas on different platforms. The simultaneous data reception by multiple receivers enables a wealth of new synthetic aperture radar (SAR) imaging modes which evaluate the scattering signals from multiple view angles in combination. Potential application areas of multistatic SAR systems include, but are not limited to, single-pass cross-track and along-track interferometry, spaceborne tomography, wide swath SAR imaging, resolution enhancement, interference suppression, ground moving target indication (GMTI), and multistatic SAR imaging. Some of these applications can also be realized via multiple data acquisitions from repeat satellite passes. However, the simultaneous data acquisition with multiple satellites in a multistatic configuration avoids temporal decorrelation and atmospheric disturbances, improves the performance, and enables the detection of fast changes. This chapter gives a thorough overview of the capabilities and challenges associated with spaceborne interferometric and multistatic SAR missions. After a short introduction to interferometric SAR imaging, several design aspects are considered including phase and time synchronisation, formation and orbit selection, as well as the choice of suitable operational modes. The achievable performance is illustrated by the two mission examples TanDEM-X and TerraSAR-L cartwheel. An outlook on advanced multistatic SAR imaging modes illustrates their future potential for a wide range of remote sensing applications. The chapter is concluded with a discussion of major challenges to implement multistatic SAR missions in space.