The surface Ground Penetrating Radar (GPR) method is comparable to the reflection seismic method. The source array is an antenna generating a very high-frequency electromagnetic pulse. The range of central frequencies used is very wide. It varies from a few tens of MHz to GHz. Electromagnetic waves propagated in the formation are recorded by a receiving antenna. The distance between the source and the receiver antennas varies from a few centimeters to several meters.
Figures show different GPR devices:
Source : https://en.wikipedia.org/wiki/Ground-penetrating_radar#/media/File:Radarsurvey.jpg
We present different field examples of application of the GPR method.