First steps towards single-pass interferometry based on a bistatic fixed receiver SAR system
Jordi J. Mallorqui(1) and Jesus Sanz-Marcos(1)
Universitat Politecnica de Catalunya (UPC),
Bistatic radar systems will pay a great role in the coming decade since a large number of radar missions are being foreseen. Using existing transmitters, formations of small passive receivers will enhance our capability to gather backscatter information from earth. A bistatic SAR system operates with separated transmitting and receiving antenna and both antennas can follow independent trajectories. If the receiver remains stationary at certain height – on the top of a high tower for example –with its antenna pointing to the illuminated scene, we deal with a bistatic fixed receiver SAR system. These systems have many advantages, for example their simplicity as the transmitter already exists (it is a parasitic system). In the same way, there is not downlink bottle-neck due to the fact that the acquisition subsystem is on the ground. In this scenario, one of the most challenging applications of bistatic fixed receiver subsystems is the deployment and synchronization of several receiver subsystems in order perform single-pass interferometry. Single-pass interferograms have high accuracy and less noise compared to interferograms generated from two acquisitions separated in time. For the orbital case, SAR satellites have a revisiting time of several weeks and therefore such an interferometry system will allow detecting and studying subsidence on the illuminated scene.
The accuracy and performance of an interferometry bistatic fixed receiver SAR system depends drastically on the geometry of the configuration and also on the instrument operating parameters. This paper is a first attempt to describe the relations between the proposed configuration and typical SAR and interferometric performance variables such as ground resolution and height extraction accuracy. This analysis will lead to the design and test of a real prototype for single-pass high-coherence interferometric imaging with a parasitic configuration.