Geosynchronous synthetic aperture radar: Concept design, properties and possible applications

Geosynchronous orbits have the unique characteristic that their orbital period is equal to one sidereal day. This configuration does provide coverage on a regional scale. This is a potential advantage in terms of system usage as the demand for some satellite services is concentrated in certain regions of the globe.This paper investigates both active and passive configurations, highlighting their different features and advantages. A synthetic aperture radar (SAR) simulator has been developed to study the influence of integration time on SAR processing in both low earth orbit (LEO) and geosynchronous SAR (GeoSAR) configurations. Different scenarios with targets affected by noise sources with various decorrelation time have been simulated in order to test the system response. Simulations show that in a geosynchronous SAR the long integration time averages out non-stationary signals within the resolution cell converting their influence to background clutter. Indeed, noise rejection is effective even if noise amplitude is one order of magnitude larger than the signal itself.The features that have been demonstrated via numerical simulations could be exploited in new SAR applications. SAR interferometry can benefit of the increased temporal correlation as all the high frequency components of interferometric phase noise have been previously filtered out. Fine temporal sampling is a feature that might be exploited for disaster management and might lead to major advances in the understanding of rapidly evolving phenomena on the ground surface. Future applications can be foreseen also in soil moisture retrieval and other related agricultural applications.