A MIMO MULTI-STATIC SAR SATELLITE FORMATION FOR HIGH RESOLUTION 3D IMAGING AT LONGER WAVELENGTHS

This paper introduces a multi-static Synthetic Aperture Radar (SAR) mission concept for high resolution 3D imaging at frequencies below 1 GHz, for which the available bandwidth allocated to Earth Observation is limited. Resolution improvement is achieved by the Fundamental Relation of Diffraction Tomography (FRDT), leading to a satellite formation where multiple transmitters are flown on the same orbit with a separation of hundreds of Km, while receivers are deployed on slightly different orbits to form interferometric baselines. For each receiver, such a formation allows for the generation of 2D SAR images with an equivalent bandwidth increase proportional to the number of transmitters, whereas 3D imaging is obtained by combining SAR images from all receivers. Beside hardware requirements – not considered in this paper - the fundamental challenge posed by this configuration is management of multiple transmissions. We show that signals from different receivers can be separated at the receiver based on the associated Doppler and direction of arrival, enabling simultaneous transmission and reception. The concept is supported by results from numerical simulations of multi-static SAR data.