SAR imaging-based techniques for Low Permittivity Lossless Dielectric Bodies Characterization

The following contribution aims to test two synthetic aperture radar (SAR)-image-based techniques to obtain geometry and constitutive parameter information about low-permittivity lossless dielectric materials. While characterization of high-permittivity dielectrics is relatively affordable in SAR images, the low amount of power reflected back by low-permittivity bodies makes their characterization a challenging task. The first proposed technique combines two illumination angles (normal and 450) to overcome the permittivity-geometry uncertainty appearing on each independent case. The second method makes use of the relationship between reflection coefficient amplitudes between two media, which can be directly extracted from the SAR image to provide an estimation of the dielectric object permittivity. Uncertainty of both techniques can be reduced by properly combining them. We validate these methods using a simulation-based application example in the form of a millimeter-wave portal-based system for concealed-object detection.