If you are curious about what is lurking beneath the ground, then you want to get a ground penetrating radar and get to work. All the way on the other side of the planet, for example, when researchers produced a ground-penetrating radargram from a cemetery in Alabama, a state in the U.S. Reflections coming back from underneath the ground showed that some reflectors were buried down there, and they may be connected to human burials.
Radar penetrating the ground (GPR) is a method of geophysical study using radar pulses to get images of the subsurface. This safe methodology uses electromagnetic radiation within the UHF/VHF frequencies of microwave bands in the radio spectrum, detecting reflections from structures beneath the ground. You can use GPR in rock, ice, soil, pavement, fresh water, and structures. It can find changes within the material, niches, cracks, and objects.
The technology of GPR uses high-frequency radio waves and transmits into the soil. When the wave hits something underneath, or at least a boundary with divergent dielectric constants, the antenna notes anomalies in the reflected signal coming back. These principles are similar to those in reflection seismology, but electromagnetic energy is the technology, not acoustic energy, and reflections show up along boundaries with divergent dielectric constants rather than acoustic boundaries.
GPR has a depth limit set by the ground’s electrical conductivity, the power radiated and the frequency from the transmitted center. When conductivity goes up, penetration depth goes down, because the electromagnetic energy dissipates more quickly into heat, leading to a drop in signal strength at depth. Higher frequencies do not go as deep as lower ones but provide better resolution instead. You get the best depth penetration in ice, where the depth can go several hundred meters. Put this technology to work for you when you are analyzing the ground down under!
Another application for GPR is in the building industry, especially where the safe cutting, coring or drilling of concrete is involved. CSI Concrete Scanning provides a gpr scanning service to the construction industry along Australia’s eastern seaboard. If you want to locate rebar, conduits etc, then you need the boys from CSI on the job!