Application of Alford rotation to ground-penetrating radar data

Abstract

We investigate the application of Alford rotation to ground‐penetrating radar (GPR) data. By recording the reflected field amplitudes using four different configurations, we extract information about the orientation of buried objects that have angle‐dependent reflectivity. In theory this method can be successfully applied to find the orientation of dipping layers, cylinders, and vertical fractures. Modeling results show angle‐dependent reflections in all three cases; as a result, we can exactly determine the orientation of these targets. Analysis of a field survey at a controlled GPR test site in which reflections were collected from an elongate cylinder buried in a homogeneous soil show good prediction of the angle of orientation of the cylinder and confirm the expected theoretical and modeling results. The Alford rotation method requires accurate data acquisition for effective practical implementation. Improved results will require exact knowledge of the radiation pattern of the GPR antennas under different circumstances.