On GPR signal polarity reversal

Ground Penetrating Radar (GPR) signal amplitude is the main signal attribute used for GPR data interpretation as, by observing its variations, it is possible to identify buried targets or material changes. 180-degree phase shifts, commonly referred to as polarity reversal, are also used to infer the material nature (e.g., voids). This paper presents an analysis of the polarity reversal occurrence through the definition of the reflection and transmission coefficient for perpendicular and parallel polarization of the electric field, showing different scenarios with the help of Finite Difference Time Domain (FDTD) numerical modelling in ideal lossless conditions as well as lossy/dispersive environments. Real radargrams are also presented to corroborate the forward modelling findings.