Radar as an active remote sensing technology has great potential with respect to precise range measurements and spatial resolution. However, its mostly mono-static implementation suffers from low or no back reflection of signals in case of plane and tilted surfaces, delivering hence no information. In contrast radiometric imaging as passive remote sensing technology uses naturally generated noise-like radiation of thermal origin, being available everywhere and from all directions. Quite often the sky can be used as large illumination source, providing rather low radiation power compared to objects on Earth, using frequencies up to few hundred GHz. Furthermore, thermal radiation originally is un-polarized, but becomes polarized when reflected partly on a dielectric surface. Hence, the use of polarimetric measurements at various incidence angles can provide information on the type and structure of the reflecting object. The approach and the measurement setup are described. Experimental results of polarimetric measurements are shown and discussed. |
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Radiometry
Polarization
Polarimetry
Reflection
Antennas
Dielectric polarization
Dielectrics