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38
12 High Frequency antennas
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MALÅ High Frequency (HF) antennas are available with frequencies of 1.2,
1.6 and 2.3 GHz. The 1.2 and 1.6 GHz antennas also have an EM
(Electromagnetic) option, giving a GPR antenna with a 50/60 Hz EM-
locator.
The HF antennas are most suitable for investigations were high resolution
is important, as for construction/concrete investigation, asphalt mapping,
ice thickness etc. See also Table 12.1.
Table 12.1.
Approximate depth ranges for different antenna frequencies.
Antenna
frequency (GHz)
Approximate Radial
Resolution
@,c=100
[m/μs] , λ
c
/4 [cm]
Approximate max
penetration depth (cm)
1.2
2.1
100
1.6
1.6
50
2.3
1.3
40
* In normal geological/construction environment absent of materials with low resistivity.
The HF antennas are one-piece radar antennas where the antenna
elements are contained in a small handheld, shielded box, which in turn
can be mounted on a wheel carriage, the HF cart. See Fig 12.1 to 12.3.
Figure 12.1
The HF antenna without the wheel carriage (1.6 GHz or 1.2
GHz with the EM option).
