Investigating multi‐polarization GPR wave transmission through thin layers: Implications for vertical fracture characterization

We investigate the controls governing the response of ground‐penetrating radar (GPR) wave transmission through thin layers in order to explore the use of variable polarization GPR signals for remote characterization of fracture aperture and fluid‐fill. We employ an experimental setting that provides controlled observations of the effects of thin‐layer properties to the transmitted GPR wavefield. GPR signals of variable polarization, variable angle of incidence, and variable frequency are transmitted through an air‐ and water‐filled layer of variable thickness. We observe that at high angles of incidence, variable polarization GPR signals display characteristic and quantifiable phase and amplitude responses that are related to thin‐layer properties. The GPR data are in agreement to analytical solutions of plane‐wave oblique‐incidence transmission through layered media. We conclude that multi‐polarization GPR observations can be exploited to determine fracture properties. This work has implications in the remote determination of fractured formation anisotropic properties, such as fluid‐flow.