Soil moisture retrieval from GNSS-R signals

Signals transmitted from Global Navigation Satellite System (GNSS) can be used for soil moisture monitoring after reflection from the Earth´s surface. In this paper, the data collected by a GNSS receiver prototype installed on a small aircraft were analyzed. A conventional GNSS L1 patch antenna up-looking with right-hand circular polarization was used to receive the direct signals, while a dual polarized RHCP/LHCP GPS antenna by ANTCOM Corporation was use to received the reflected signals. The system was calibrated considering the signals reflected from water surface. Soil moisture was retrieved from the power ratio of LH reflected SNR over direct RH SNR regardless of the surface roughness and incoherent components. Results showed good correlation with the types of underlying terrain.