Conceptual Schematic of GPR Technology

Each anomaly is defined by a change in a dielectric of the material.  The dielectric value of a material is defined by the speed in which a radar wave passes through a material.  Because every material has its own dielectric value it is impossible with radar to identify exact materials or anomalies without physical evidence to support the GPR signals.  The determination of the cause of the changes in dielectric values can only be verified through physical testing methods.  Therefore, subsurface targets are always referred to as anomalies or unknown targets.  In addition, these changes in dielectric values also change the speeds in which radar can pass through materials, making depth readings estimated values.  The contrast of different dielectrics is shown by the radar wave and can then be used to define the limits of contrasting materials underground.  These boundaries formed by the radar signal are then used to identify anomalous features underground.