BISAR MAPPING I. THEORY AND MODELLING

Bistatic Synthetic Aperture Radar (BISAR) is an active imaging system for which the transmitting and the receiving antennas are located on separate platforms. During its motion, the transmitting antenna emits towards the ground a burst of pulses at a frequency called Pulses Repetition Frequency. Every pulse affects an area of the ground after a propagation time proportional to the distance transmitter-scene. The bistatic receiving antenna receives a signal from the ground after a propagation time proportional to the distance scene-receiver. A communication link between the transmitter and the receiver is necessary to measure the phase of the received signal with respect to that of the transmitted signal. This paper presents, initially, the modeling of a moving polarimetric radar working in bistatic configuration. We propose to write the received signal as a function of time for the general case where the transmitter, the target and the receiver are moving. As BISAR and MONOSAR (Monostatic Synthetic Aperture Radar) geometry differ substantially, the BISAR temporal requirements are examined in detail. The radiolink is completely modeled. The companion paper is devoted to the development of two processing methods for bistatic radar imaging. Simulation and experimentation will be presented.