to the
Determination of soil moisture in the microwave region
99
fc<5 been
ib st rates
on t o b e
f i 11 er s
»ups the
: or r ec t ed
s v e been
ate, the
As was
¡e other
y partly
her »
¡ted the
tee 'for
i gnat.ur e
ubstrate
s is the
ch have
her the
tion as
aerial
Laboratory ex per i ¡»ents at the CIPE under defined conditions
Physical bodies at ! = 300 K emit infrared radiation with a maximum
value at \ ~ 10 pm. In the microwave region there is still a detectable
amount of radiation \ so called Res-tstr ahl ung) which is lower in
intensity by 10 to 15 orders of magnitude. With the intensity of the
emitted radiation depending exponentially on the body temperature in
the infrared region, the relationship in the microwave range is
approximate!y linear. Hence the intensity of the emitted radiation is
/
linear to the physical temperature of the body (which can be determined
for instance by a mercury thermometer) and to the emissivity. This
product is also called the "black 11 temperature or brightness
t e m p e r a t u r e / 2 / ;
I
If
£
the microwave radiometer is calibrated T B can be
depends physica11y on the electrical permitivity
measured direc1.1
. By knowing T
is possible to determine the material dependant emissivity (or factor
gf emission). In physical terms £ depends on the complex permitivity
of the substance and thus on its real part permitivity and on its
electrical conductivity /3/.
In geology these physical parameters are mainly influenced by /4,5/;
- water content of the material concerned,
- binding force of the water dipoles, to the crystal lattice (e. g. the
water dipoles between the clay mineral layers),by
~ density of the material.
Moreover the' surface roughness of geologic bodies influences £
si gni f i can11 y /6,7/ .
The technique of microwave sensing has been applied in the lignite
industry for mapping moisture anomalies in pleistoscene loose
sediments. The real temperature T of these sediments can be considered
to be as constant. For material diagnosis it is important to
