Multilayered Circular Dielectric Structure SAR Imaging Using Time-Reversal Compressed Sensing Algorithms Based on Nonuniform Measurement

In this letter, an algorithm for synthetic aperture radar imaging of electrically small targets embedded in multilayered cylindrical geometries (e.g., pipes) using nonuniform measurement points is presented. In contrast to previous approaches, this algorithm is able to efficiently handle nonuniform points without exhibiting relevant side lobes in the image. For these purposes, the approach exploits a flexible time-reversal (TR) algorithm enhanced by compressed sensing (CS). The theoretical performance of the algorithm is studied in terms of the point spread function and several images are presented using synthetic full-wave data from CST Microwave Studio. In addition, the approach is empirically validated by performing microwave imaging of a polyvinyl chloride pipe. The results demonstrated that the TR-CS algorithm provides an effective focusing technique for dense nonuniform measurement points, as well as for sparse nonuniform measurement points.