Predictions in Ungauged Basins: Promise and Progress (Proceedings of symposium S7 held during the Seventh IAHS Scientific Assembly at Foz do Iguaçu, Brazil, April 2005). IAHS Publ. 303, 2006, 274-285.

 

Frequency-domain analyses of GPR waveforms: enhancing near-surface observational capabilities

 

GUY SERBIN1 & DANI OR2

1       Department of Plants, Soils, and Biometeorology, Utah State University, Logan, Utah 84322-4820, USA.

        now at: Geosciences Dept, University of Rhode Island, Kingston, Rhodes Island 02881 USA

guy.serbin@gmail.com

2       Department of Civil and Environmental Engineering, University of Connecticut,261 Glenbrook Road,
Unit 2037, Storrs, Connecticut 06269-2037, USA.

        now at: Laboratory of Soil and Environmental Physics (LASEP), School of Architectural,
Civil and Environmental Engineering (ENAC/ISTE), Ecole Polytechnique Federale de Lausanne (EPFL), Bâtiment GR 2 (room 554), CH-1015 Lausanne, Switzerland

 

Abstract Greenhouse and field wheat canopy time domain (TD) ground-penetrating radar (GPR) measurements were analysed in the frequency domain (FD) using Fast Fourier Transforms (FFT). FFTs of top canopy, soil surface, and subsurface Al-foil termination reflections and entire profiles were compared with TD surface reflection magnitudes (SR) and signal propagation time (PT) estimated water contents Qv. Direct relationships were found between TD and FD SR magnitudes and Qv, and indirect relationships between TD SR and PT values and FD SR components. GPR profiles FFTs showed interference patterns attributed to interactions between reflecting layers within the profile. FD profile radar backscatter coefficient s0 values at 430 MHz (P-band) and 1.26 GHz (L-band) showed that near-surface reflective objects biased results, particularly at lower frequencies where signal penetration depths were greater. The final results show that a single monostatic horn antenna with sufficient bandwidth can determine near-truth radar backscattering parameters for air- and spaceborne platforms.

 

Key words  canopy scattering; horn antenna; radar remote sensing; soil water content