Ground Radar
The principle of the method is based on the emission of high-frequency electromagnetic waves, which are reflected when they hit different materials or structures in the ground.
Georadar is widely used for the exploration of near-surface structures. It can find cables, cavities, belts of soil water and geological layers. Depending on the application, the measuring frequencies used are between a few megahertz and some gigahertz. Depending on the measuring frequency, the resolution of the measurements is some meters to some centimetres. The possible measuring penetration depth depends on the frequency and also strongly on the conductivity and dielectricity of the medium. In Antarctic ice, which has a very low conductivity, a penetration depth of several kilometres is possible, whereas highly conductive soils saturated with saltwater only allow a penetration depth of some centimetres. BGR uses several measuring systems. A pulse radar system that can be applied at the surface was built by http://www.geophysical.com/, another one built by Hentschel has antennae to measure in frequency ranges of 20 MHz to 800 MHz.
Additionally, a Stepped Frequency Radar System for operation in a helicopter is being developed, it was also already tested on the ground.
Measurement results:
Application:
BGR’s ground radar systems are only operated for test purposes. Test areas have been up to now:
- gravel bank, Rügen island
- limestone quarry, Omya
- farm tracks in the foreland of the Harz mountains
- karst area Wulfbachquellhöhle
- ground test field Fuhrberg
- soil test field Ruthe
- military training area Letzlinger Heide
- deciduous forest Hainich
- coalfire in China (coalfire.org)
Available measuring equipment
BGR uses pulse radar systems from Hentschel and GSSI as well as its own developments.