Ground Penetrating Radars for Utility Locators
Welcome to our comprehensive Ground Penetrating Radar (GPR) equipment reviews database.
Our database is curated to guide professionals, researchers, and utility locators in selecting the perfect GPR system for their unique needs.
Below are the Ground Penetrating Radar Equipment Product Reviews split into two categories, large/cart/push/geophysical gpr's and small/mini/portable/concrete gpr scanners.
Ground Penetrating Radars.
Overview for GPR Technology for Utility Locating
Ground penetrating radar (GPR) can locate both metallic and non-metallic utilities. GPR is a wave propagation technique which uses high-frequency electromagnetic waves, usually in the range 50 MHz to 4 GHz.
A GPR transmission antenna transmits the waves into the ground. When the waves encounter a buried object or a boundary between materials having different dielectric constants, they are reflected or refracted or scattered back to the surface.
A receiving antenna then records the variations in the return signal.
Overall propagation into the ground is a factor of frequency, power, and soil resistivity.
Frequencies around 400 MHz are typically used for utility locating. Utility detection occurs when the boundary of the utility is different dielectric constants than the surrounding soil.
A very different boundary produces the best reflection (i.e., metallic utility buried in dry sand).
The smaller the utility, the higher the frequency and contrast of materials dielectric constants, is needed to detect it.
Limitations
However, the higher the frequency, the quicker the signal dissipates with depth. A general rule of thumb for current technology in practice is a depth to diameter ratio of 12 to 1, under ideal conditions. That is for accurate detection, usually a 200mm utility target at a max depth of 2400mm/2.4m is needed for clear indications. Of course this varies of soil/signal penetration conditions.
The more conductive is the surface (steel reinforcement, de-icing salts, saline water, and soil with high organic or iron contents) the less effective are GPR systems. Ideal conditions for GPR include dry sand while least optimal conditions are represented by marine clays and similar highly conductive soils.
Conclusion
GPR can determine relatively accurately depth of a utility, when calibrated correctly. Calibrate with known object depth in same medium as targets. Calibrate to dielectric medium, and/or using hyperbola matching.
In some cases where the utility itself cannot be imaged, GPR can detect a trench suggesting the presence of a utility.
Ground Penatrating Radar Utility Locating Knowledge Quiz
Test you knowledge about GPR utility locating.
Click the link to take you to a google form quiz. 
Its free and you can get the questions and answer sent to your email. 