A Subaperture Range-Doppler Processor for Bistatic Fixed-Receiver SAR

Abstract:
In Bistatic SAR systems, transmitting and receiving antennas are mounted on different platforms and can follow independent trajectories. The Fixed-Receiver geometry makes reference to the case where the transmitter moves through a straight trajectory while the receiver remains stationary with its antenna pointing to the illuminated scene. Several processing strategies have been used to solve the azimuth-variant characteristic for this geometry but none has shown an acceptable accuracy vs. efficiency trade-off. In this paper we present a novel technique used to merge the accuracy of a time-domain algorithm and the time efficiency of a conventional SAR processing one, the Range-Doppler, by using sub-apertures. We will validate the focusing algorithm with the first bistatic SAR images acquired by a hardware prototype, called SABRINA, designed to parasitically gather the backscattered signal of Envisat and ERS-2 satellites in a fixed-receiver geometry. We will show the first processed images using descending passes over Barcelona with a bistatic angle of 75deg.