Gira 5110 00 Product Documentation page 43

i Care is required when a building is equipped with shielding materials to reduce
electromagnetic waves. Flush-mounted appliance boxes with a conductive coating are not
usually suitable for radio products. Special shielding plasters and plasterboard protection
plates, into which conductive fibres are worked, reduce the permeability of radio waves by
up to 95%. The same applies to stands, into which high level of metallic components (e.g.
supporting parts, metallise insulation material) are integrated.
i Due to the wide range of influences, it is difficult to evaluate radio sections in buildings.
Eventually a manufacturer of radio products - also of other systems such as Wi-Fi - cannot
make any binding statement on the range of radio transmission in buildings. For this
reason, the free-field range is always stated, which refers to an uninterrupted radiation of
the radio waves and optimally aligned antennas. Provided that there are no special
measures for shielding in buildings, this means that targeted radio transmission should be
possible.
Additional attenuation in a building or in a more or less free field (outdoors) is created when the
antenna of the transmitter or receiver is mounted at a low ground height. KNX RF radio sensors
and actuators should therefore be mounted as far from the ground as possible.
The mounting of a transmitter or receiver in the ground (e.g. in a suitable installation box) should
be avoided, particularly outdoors. The radio range would be restricted to such an extent that
radio transmission would scarcely be possible.
i We recommend installing KNX RF push-button sensors at a standard mounting height of
1.05...1.50 m.
Electrically conductive materials cannot be penetrated by electromagnetic waves. Metallic
components of buildings, e.g. furniture or steel reinforcement rods in concrete (Figure 14), but
also metallic design frames or design parts with metallic coatings thus have a shielding effect.
Metallic shieldings can also be used consciously to keep an area free of radio waves.
Figure 14: Radio shadow in a building due to metallic parts (idealised)
Radio waves reach the receiver both directly (through the air) and also via diversions (multiple
route radiation). Such diversions are created by reflections of the radio waves at boundary
layers to other materials, e.g. on the surfaces of walls or ceilings. Radio waves of an identical
Order No. 5110 00
Software "Media coupler / repeater"
Parameters
Page 43 of 57