A Novel Multistatic SAR for Subsurface Imaging: Detection and Localization of Buried Pipelines and Leaks

Password: SUBSAR

Ground penetrating radar (GPR) is widely used for many tasks in infrastructure development and maintenance, mining, archaeology as well as construction industries. Compared to traditional monostatic GPR systems, a multistatic subsurface synthetic aperture radar (SAR) system where a fixed transmitter (Tx) illuminates the underground and a moving receiver (Rx) samples the scattered signals around the transmitter provides major advantages in subsurface imaging and target detection. Most notable advantages are the faster acquisition time, the improved lateral resolution as well as the higher gain resulting from coherent processing. Nonetheless, the complexity of such subsurface SAR system introduces new challenges which this dissertation is aiming to address.

One challenge occurs in full-wave simulation where the number of the required simulations increases with the number of SAR samples. Another challenge is encountered in detection and localization of extended targets such as pipelines using traditional SAR imaging algorithms that assume point-like scattering behavior which is incompatible with extended targets. The third challenge is faced in pipelines leaks detection as the scattered signals from pipelines tend to be strong overshadowing the scattered signals from the leak. Lastly, the multistatic SAR configuration suffers from the effect of Tx-Rx signal leakage that hinders the ability of the radar to detect buried targets’ signals.

By utilizing reciprocity theorem, the dissertation proposes a time-efficient full-wave simulation method for multistatic SAR. Moving to pipelines detection, the dissertation addresses the challenge by devising a novel algorithm that tracks the pipelines dynamic scattering phase centers leading to successful detection and localization. Furthermore, the same algorithm is utilized to estimate and eliminate pipeline contribution to the radar response leading to an improved performance in pipeline leaks detection.  Finally, the Tx-Rx signal leakage is addressed by proposing an array null-synthesis procedure that cancels the signal leakage while preserving the buried targets signals.

Chair: Professor Kamal Sarabandi