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Fig. 8.23 Frequency dependence of attenuation coefficient for SHF channel of measuring system
Fig. 8.24 Frequency dependence of the power attenuation in the pine branches under humidity
equaled 62.7 %. Notation 1 values of attenuation measured without correction; 2 corrected values
of attenuation; and 3 approximation of curve 2 by power function. Correction of measured values
of attenuation was realized by means of neutralization of the power percolation effect from
waveguide (Chukhlantsev 2006)
was studied by comparing the data with and without vegetation samples in the
waveguides. Basic electrical characteristic of laboratory complex is shown in
Fig.
8.23
It is clear that attenuation was less than 5 dB in the range of 0.8
-
2.15 GHz. The same dependence is observed in the range of 0.8
-
10.0 GHz. Some
experimental results are given in Figs.
8.24
,
8.25
and
8.26
.
Experiments in
field conditions were conducted at the territory of forests using
the lowering unit (Figs.
8.27
and
8.28
). The territory includes grassy and forested
areas of different plant type and density. The generator is installed behind the trees.
A receiver is located in different areas at different heights of tree crowns. The
assessments of the attenuation were obtained by comparing the intensity of signals
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