Forward-Looking Ultra-Wideband Synthetic Array Imaging

The expansion of microwave imaging applications in various fields proposes increasingly higher requirements (including spatial resolution, dynamic range, and signal-to-noise ratio) for microwave imaging systems. To achieve high-quality imaging, microwave imaging systems generally exploit spatial-, frequency- and polarization-diversities to probe objects of interest for information extraction. In practice, they are implemented by using array-, wideband/Ultra-wideband (UWB)-and polarimetry-techniques. So properly exploring these techniques is of great importance to design an advanced microwave imaging system. A motivation for the research presented in the thesis is to develop a ground penetrating radar (GPR) system to predict hazards ahead of tunnel boring machines (TBM) during tunnel excavation. In this circumstance, GPR antennas are mounted on the cutter-head of a TBM. With the rotation of the TBM cutter-head, GPR antennas collect electromagnetic (EM) signals over a synthetic circular aperture, which leads to the Radial-scanned Synthetic Aperture Radar (RadSAR). The rotation of the antenna array benefits the formation of the RadSAR but makes it distinct from traditional SAR modalities as well.