Bistatic GPS signal reflections at various polarizations from rough land surface with moisture content

Bistatic L-band GPS systems operating from airborne or space-borne platforms received an interest for their advantages in remote sensing of land and ocean surfaces. Currently, researchers use the GPS signal for bistatic ocean scatterometry and wind retrieval. Extending this method also toward remote sensing of soil moisture is natural, since soil reflectivity at the GPS frequency is sensitive to moisture content. The authors show that the ratio of GPS reflected signals having a different polarization state can be useful measurable characteristics for soil moisture. They present results of GPS signal modeling that illustrate regimes most convenient for soil moisture retrieval.