Ground-penetrating radar measurement of soil water content dynamics using a suspended horn antenna

A ground-penetrating radar (GPR) with a suspended horn antenna was used to obtain continual measurement of near-surface soil water content dynamics within a well-defined footprint. Water contents inferred from radar surface reflectivity (SR) were in agreement with gravimetric measurements from the top 1-cm soil layer. This sensitivity to top 1 cm was confirmed by comparison of SR with deeper measurements (1-5 cm) obtained by time-domain reflectometry. Measurements over sand and silt loam showed the role of soil type in controling near-surface dynamics of soil water due to evaporation and drainage processes. GPR with a horn antenna provided insights into physical processes that could affect larger scale radar platforms (air- or spaceborne) and enabled verification of radar measurements at well-defined spatial scales and detailed temporal resolutions not available by other radar remote sensing systems. Index Terms--Dielectric measurements, ground-penetrating radar (GPR), remote sensing, soil water content.