Technical information

The question of range.
Especially inside buildings,
radio waves can be subject to
a number of different influences
that weaken the signals and thus
shorten their range. That is why
all manufacturers of radio prod-
ucts generally indicate the free-
field range, which refers to the
uninterrupted propagation of the
radio waves and optimally
oriented antennas. For products
of the Berker radio bus system
this range is generally 100 m.
Unless a building is specially
shielded by means of certain
measures, this means that there
will be no problem implementing
radio links through three walls and
two ceilings. Nevertheless,
in any building there may be
advantageous and disadvanta-
geous locations for installing
radio bus components.
Avoiding overmodulation.
To avoid overmodulation, a mini
-
mum distance of 0.5 m should be
maintained between transmitters
and receivers.
Radio shadows from metals in
the building. The areas behind
metallic building elements such
as piers, ceiling beams and fire
doors constitute radio shadows
(see illustration below). Receivers
installed in such shadows can-
not receive signals over a direct
pathway, and have to depend on
reflected radio waves. Please keep
this in mind during placement.
For this reason, maintain a mini
-
mum distance of 10 cm from
metallic walls or doors.
Windows. More and more often,
modern buildings are making use
of low-E glass with metal coat-
ings. These windows attenuate or
reflect radio signals very strongly.
Normal windows are transparent
to radio waves, which is particu-
larly advantageous for applications
outside of the building.
Thermal insulation. Sometimes
buildings are fitted with thermal
insulation of insulating wool which
has metal foil applied to it. If this
insulation is used in the roof area,
it has no effect on radio transmis-
sion that takes place only within
the building. If, however, hollow
lightweight walls are filled with
such insulation, then the metal foil
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FOR A PERFECT INSTALLATION
BASICS OF RADIO TECHNOLOGY