Co-polarimetric ground-penetrating radar amplitude and phase variation with offset (APVO) analysis

Abstract Ground-penetrating radar (GPR) has emerged as a powerful geophysical tool for subsurface characterization. However, conventional fixed-offset systems often lack the capability to fully resolve complex dielectric properties. This study presents an enhanced amplitude and phase variation with offset (APVO) analytical framework for co-polarized GPR systems, which significantly improves the detection of subsurface anomalies through comprehensive characterization of electromagnetic responses. We systematically investigate both vertical–vertical (VV) and horizontal–horizontal (HH) polarization modes, and address key limitations in existing approaches by focusing on the amplitude variations caused by the first reflection. For VV polarization, we develop an optimized exponential gain compensation method that demonstrates superior performance in correcting signal attenuation and preserving true amplitude relationships compared to conventional power-law approaches. In HH polarization analysis, we experimentally validate the remarkable stability of Brewster angle detection across varying target geometries, confirming its dependence on dielectric contrast. Our phase-tracking methodology achieves excellent agreement with theoretical predictions, enabling accurate determination of subsurface dielectric properties. The proposed framework combines amplitude and phase response patterns to differentiate various subsurface anomalies, including cavities, light non-aqueous phase liquids contaminated zones, and saturated layers. These advancements offer significant improvements over conventional single-offset GPR measurements and have practical applications in environmental monitoring, archaeological surveys, and infrastructure inspection.