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Earth and Space Sciences · 术语表

什么是 Ground-penetrating radar; radargram？

又称： ground-penetrating radar · radargram

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

Ground-penetrating radar sends short pulses of radio waves, of frequencies from about $100\,\mathrm{MHz}$ to $1\,\mathrm{GHz}$ 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\,\mathrm{m}

deep and the water table

1.5\,\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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