A Bistatic SAR for Earth Observation

Bistatic radar is an active microwave sensor operating with separated transmitting and receiving antennae. This paper deals with a spaceborne mission of a bistatic synthetic aperture radar based on a small satellite flying in formation with ENVISAT along parallel orbits, and equipped with a receiving only microwave system, which catches the ASAR echoes. The proposed system does not require any modification of existing ENVISAT design and operation; in fact it is assumed that ENVISAT is non-cooperative. After an introduction to the original scientific activities and applications achievable using bistatic data as further input thanks to the capability of a multi-angle observation, the paper presents numerical results of a simulation aimed at characterising some radiometric and geometric aspects of bistatic imagery. In particular, the effects of a frequency offset, caused by differences in local oscillators, and of variable bistatic geometry, caused by spacecraft separation along the orbit, are put in evidence.