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Earth and Space Sciences · Glossary

What is Ground-penetrating radar; radargram?

Also known as: ground-penetrating radar · radargram

Definition 31.14 University Earth and Space Sciences — Year 3 · Chapter 31 — Field and Lab Methods III

Ground-penetrating radar sends short pulses of radio waves, of frequencies from about 100 MHz100\,\mathrm{MHz} to 1 GHz1\,\mathrm{GHz} and durations of a few nanoseconds, from an antenna on the ground, and records the echoes from contrasts of permittivity and conductivity below. A radargram is the display of the recorded traces side by side along the profile, the two-way travel time increasing downward.

A radar profile over the alluvial floor: a drain pipe 0.8\, m deep and the water table 1.5\, m deep in alluvium of relative permittivity 4 (left), and the arrival times of their echoes (right). The pipe returns a hyperbola, whose flanks the antenna records before it is above the pipe; the water table, a plane, returns a flat echo.
A radar profile over the alluvial floor: a drain pipe 0.8 m0.8\,\mathrm{m} deep and the water table 1.5 m1.5\,\mathrm{m} deep in alluvium of relative permittivity 4 (left), and the arrival times of their echoes (right). The pipe returns a hyperbola, whose flanks the antenna records before it is above the pipe; the water table, a plane, returns a flat echo.
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