Article,
Radar attenuation by sand: Laboratory measurements of radar transmission
IEEE TRANSACTIONS ON GEOScience AND REMOTE SENSING, 39 (11): 2521--2526 (2001)
Abstract
Under certain conditions, radar is able to penetrate loose sand to
reveal subsurface geology in and areas. However, backscatter from
the subsurface is modified by signal attenuation by the sand. To
quantify the amount of radar attenuation, a laboratory experiment
was conducted to measure radar transmission as a function of radar
frequency and sand moisture. The frequency range covers P- through
X-bands (0.5-12.6 GHz), and the moisture contents of the sand were
0.3, 4.7, and 10.7% by volume. Results show that addition of the
sand causes a small decrease in transmission at low frequencies for
all three moisture levels, but the sand causes a larger decrease
in transmission at higher frequencies. The transmission measurements
were also used to calculate values for attenuation. The dry sand
resulted in attenuations of less than 6 dB/m over the entire frequency
range. Sand with moisture contents of 4.7 and 10.7% volume caused
by attenuations greater than 150 dB/m at the highest frequencies,
but the attenuation values calculated for P- and L-band frequencies
were less than 10 dB/m even at these relatively high moisture levels.
These results challenge previous restrictions that sand must be extremely
dry for radar penetration to occur.
