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Ground Penetrating Radar |
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RADAR is an acronym coined in the 1934 for RAdio
Detection And Ranging (Buderi, 1996; Centre for the History of Defence
Electronics). The first ground penetrating radar survey was performed in Austria
in 1929 to sound the depth of a glacier (Stern, 1929, 1930).
The technology was largely forgotten (despite more than 36 patents filed between 1936 and
1971 that might loosely be called subsurface radar) until the late 1950's when U.S. Air
Force radars were seeing through ice as planes tried to land in Greenland, but
misread the altitude and crashed into the ice. This started investigations
into the ability of radar to see into the subsurface not only for ice sounding but also
mapping subsoil properties and the water table (Cook, 1964;
Barringer, 1965; Lundien, 1966). In 1967, a system much like Stern's original
glacier sounder was proposed, and eventually built and flown as the Surface
Electrical Properties Experiment on Apollo 17 to the moon (Simmons
et al., 1972, see also the Apollo 17 Lunar
Sounder Experiment). Before the early 1970's, if you wanted to do GPR, you
had to build your own (Ohio State University
Electroscience Laboratory). But in 1972, Rex Morey and Art Drake began Geophysical Survey Systems Inc. to sell
commercial ground penetrating radar systems (Morey,
1974). Thus began an explosion of applications, publications, and research,
fostered in great part by research contracts from the Geological Survey of Canada, the U.S. Army Cold Regions Research and Engineering
Laboratory (CRREL), and others. There are now over 300 patents that might
loosely be related to ground penetrating radar around the world (Patent Office), several companies
making commercial equipment, many companies offering it as a service, and many
institutions performing research (GPR Links). Ground
penetrating radar is sometimes called georadar, ground probing radar, or subsurface radar. Electromagnetic Wave Propagation Velocity Wavelength Attenuation Dispersion Rocks, Soils and Fluids: Electrical Properties Magnetic Properties Environmental Influences Heterogeneity, Anisotropy and Scale Radar Equation Scattering Polarization Fresnel Reflection Snell Angle Stokes Matrix Poincare Sphere Antennas Coupling Near / Far Fields Waveguides Multipathing Resonance Survey Design Contrast Geometry Resolution Depth of Investigation Orientation Data Acquisition Data Processing Modeling Interpretation Uncertainty Applications: Noninvasive Surface Borehole Airborne Satellite and Space |
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