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Bohling, Geoffrey C. / A ground penetrating radar study of water table elevation in a portion of Wisconsin's central sand plain
[DNR-050] (1988)

III. Radar theory and hydrogeological applications,   pp. 19-32 PDF (3.7 MB)


Page 21

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tromagnetic energy) the above parameters appear in the following combi-
nations:
ce =--   +we'                          (4)
and
e    C-E     -                        (5)
w
where w is the angular frequency of the electrical field. The parameters
defined in equations 4 and 5 are called the real effective conductivity and
the real effective permittivity, respectively. The relative real effective per-
mittivity, Ee r, is defined such that
Ee -eTCO.                       (6)
In the following discussion the term " dielectric constant" refers to Ee
C. Signal Propagation Velocity
In most practical applications, the GPR signal can be considered to
be a wave packet moving at a velocity of
C
V =     e(7)
where c = the velocity of light in a vacuum (about 1 ft/ns) (Annan and
Davis, 1976; Shih et al., 1986; Ulriksen, 1982; Houck, 1984; Wright et al.,
1984; Bogorodsky et al., 1985). Over the range of frequencies of commer-
cially available GPR units, d ' of earth materials is essentially equal to
zero, so that Ee r is approximately equal to the real part of the relative


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