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Minimum Distance from lateral bounds
The microwave field of the surface sensing head MOIST-R1M V2 has some lateral
extent. Therefore a minimum distance from lateral bounds must be kept to avoid
falsification of the measurement.
The minimum distance from the lateral bounds of the test object is given by half
the diameter of the sensing head.
In principle moisture measurement with the surface sensing head MOIST-R1M V2 is
also possible when the distance to lateral bounds of the test object is lower.
Before doing such a measurement hf sensor must be consulted, because usually
for such measurements special arrangements must be used.
6.3.2 Moisture Measurement in the volume of the test object with sensing head
MOIST-PM V2
The volume sensing head MOIST-PM V2 contains an antenna arrangement, which
enables a penetration depth of up to 30 cm. It is well suited for moisture measurements
in the volume of the material. Measurement is realized on the basis of a reflection
principle, i.e. the part of a microwave is measured which is reflected from the material
dependent on its moisture content.
For realizing the measurement the sensing head has to be put smoothly onto a plain
surface of the material under test. Generally care has to be taken that there are no
metallic bodies under the test object.
The antenna arrangement transforms the electromagnetic wave oscillation generated in
the sensing head into an electromagnetic wave propagating into the test object.
Contributions to the reflection of this wave do not only come from the surface of the
material, but also from the deeper layers of the test object. The portions of the
contributions of the single volume elements decrease with increasing depth, but much
slower as for the surface sensing head MOIST-R1M V2.
Sensing head
Test Object
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