The theory behind ground penetrating radar is simple. Impulses of radio frequency are emitted from an antenna into the earth’s subsurface. This frequency is then reflected back to the antenna from the materials found in the earth’s surface. An on board computer calculates the signal strength of the reflected radio waves, as well as the amount of time it took for the waves to reflect back to the GPR.
When strong signal strengths are received by the machine, this indicates that the ground penetrating radarunit has passed over an object with a higher than normal density. The most common subsurface commodities that can produce high density GPR results are large rocks, buried rubble, and underground utilities.
The GPR unit can be useful to help identify areas of density change in the earth’s subsurface, along with the location of man made objects such as underground pipe, cable utilities, and underground storage tanks. We find that the GPR can be particularly useful when attempting to locate underground plastic pipes, such as water lines and gas lines.