Measurement of the Bistatic Scattering Coefficient over Wide Angular Ranges Using SAR on Unmanned Aerial Vehicles

Abstract:
Bistatic radar imaging has been an important topic ever since radar scattering and imaging has been made possible. Nowadays, Unmanned Aerial Vehicle (UAV)-based synthetic aperture radar (SAR) systems open up a completely new space for measurements that have not been carried out before. UAVs not only enable very accurate and cost-effective monitoring of local areas with unprecedentedly short revisit intervals, but also the use of configurations with large bistatic angles, which are of difficult implementation for spaceborne and airborne systems and have been so far used only in the context of ground-based (surveillance) radars. This paper shows how to measure the bistatic scattering coefficient of a surface over wide ranges of bistatic angles using a SAR mounted on UAVs. Starting from the necessary, basic geometrical definitions, it is shown how to choose geometrical configurations to achieve specific bistatic angles under the constraints of desired ground resolution and ground area coverage, while at the same time avoiding ambiguities. Moreover, the feasible bistatic angular coverage for a ground target is analysed such that conclusions can be drawn about how to maximise this coverage for given measurement scenarios. This analysis prepares for the execution of field demonstration and measurements with UAVs aiming at fully characterizing the bistatic scattering of surfaces of interest.