Bistatic radar using a spaceborne illuminator

A bistatic radar has a physically separated transmitter and receiver. This presentation investigates a bistatic radar system which uses a spaceborne synthetic aperture radar (SAR) transmitter on board the European Space Agency's Envisat satellite and a stationary, ground based receiver. The advantages of this variant of the bistatic configuration includes the passive and therefore covert nature of the receiver, its relatively low cost, in addition to the possibility of using a non-cooperative transmitter. The theory behind bistatic SAR systems is presented, with a comparison made between the specific case investigated and a monostatic system. The experimental system is also described. This includes the transmitter and the bistatic receiver, which uses two separate channels, for the direct signal from the satellite (for synchronisation purposes) and the reflected signals from the imaged scene. A bistatic SAR processing scheme using an adapted chirp scaling algorithm is presented. The principal results of several bistatic imaging experiments are then considered, and it is demonstrated that focused images may be produced with such a system. The optimum choice of look direction must be weighed against possible direct signal interference in the reflected signal channel. Aspects of the system that could be investigated in the future are identified, for example the addition of an extra channel to the receiver in order to perform bistatic displaced phase centre antenna or interferometry experiments.