BERTHOLD TECHNOLOGIES LB 567, Руководство пользователя

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Chapter 4. Getting Started
48 MicroPolar 2 (++) LB 567
Setup of the Horn Antennas
Install both horn antennas in diametrically opposite locations
Transmitter and receiver must always have the same polari-
zation; the couplers must always point in the same direction.
Typical distances between the antennas are 30 to 80 cm, but
may be up to 1 or 2 m.
The coupler should always face the material flow, because
then the waves are not deflected so much by the material flow.
The transmitting antenna must always be installed below, the
receiving antenna, above the conveyor belt. Depending on the
layer thickness and the water content, less radiation will then
get outside the material flow.
When transmitting the upper and lower belt, you should allow
for incorrect measurements caused by the geometry. Suffi-
cient room for the horn antennas should be available below
the upper belt. If necessary, a belt deflection has to be carried
out, or you have to check if spiral antennas are better suited.
Select the installation site of the horn antennae such that they
will not be affected by dirt on the radiation exit window,
Install the reference cable parallel to the signal cables. Its
length corresponds to the sum of both signal cables.
Install the antennas as far away as possible from the rollers or
other metallic objects.
The supplied HF cable can be bent depending on your installa-
tion situation (min. bending radius 10 cm). Fix the cables to
prevent them from slipping. Firmly tighten the cable connector
with the spigot nut. It is not permitted to change the cable
lengths or to use other cables.
In wet areas the cable connection always have to face down.
Make sure that no humidity can penetrate. If necessary, you
have to seal the HF-connection by taking suitable provisions.
To ensure a satisfactory measurement on conveyor belts, the
material layer should be plane-parallel with the belt. With bulk
goods, one can achieve this smoothing effect quite easily, for
example, by dragging a hinge-mounted plate over the material
surface. The same effect is obtained with a free-sliding ski
moving through parallel guide rods over the material surface.
Especially for grain sizes above 10 mm, the ski is superior to
the mobile plate. Experience shows that a fairly smooth sur-
face and homogeneous layer will be obtained only when the
minimum layer thickness is at least three times as high as the
maximum grain size. For fine-grained materials we recom-
mend using a "plow" to smooth the material surface without
significantly changing the bulk density, especially if no bulk
density or area weight measurement is available.