Nadir-Looking Synthetic Aperture Radar (NadirSAR)

NadirSAR offers high-resolution imaging of targets, lines of communication, and buildings in urban canyons, rough terrain and light foliage areas. This capability can bridge the gap between down-looking LIDAR sensors and side-looking microwave and foliage penetrating UHF SAR systems such as TRACER. In a previous effort for RRTO, TSC and SDL experimentally demonstrated the feasibility of X-band NadirSAR imaging against targets in urban and light foliage. In the Phase I STTR, our team designed a Ku-band upgrade for the FlexSAR testbed, extended the proven 3-D Tomographic processing approach, and developed a novel Sparse SAR Reconstruction technique. The objectives of Phase II are to mature these innovative NadirSAR processing algorithms, define optimum flight paths to maximum 3-D imaging resolution, and upgrade the SDL testbed to collect Ku-band NadirSAR data. Our team will evaluate imaging metrics including resolution using calibration targets, and characterize NadirSAR performance against targets of interest in various environments. TSC will also plan the transition of NadirSAR into operational US Army Ku-band radar systems, including VADER and STARLite, by addressing validation flight testing, real-time processing architecture, and CONOPS. The expected results of this effort include determining the best polarization, nadir-looking geometry, and nonlinear flight path for detecting hidden targets.