Published: 18.07.2019
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3.1.1 Signal range
Because the radio signals are electromagnetic waves, the signal becomes weaker the further it travels.
The radio signal coverage is also decreased by specific materials that are in the propagation direction.
The radio waves can penetrate walls, but the signal is dampened more than in the direct line of sight
path. See the following table for the different construction material effect on the radio signal strength.
Material
Range reduction compared to direct line of sight
Wood, plaster, uncoated glass
0...10 %
Brick, press board
5...35 %
Concrete, reinforced concrete
10...90 %
Metal, aluminium lining
90...100 %
3.1.2 Effect of metal structures
Metallic parts, e.g. wall reinforcements, thermal insulation metal foils and metallized heat-absorbing
glasses reflect radio waves. This creates a so called radio shadow behind the structure.
The radio transmission may work even if there are metallic obstacles on the direct path to the receiver.
The radio waves reach to the destination by reflecting from metallic objects and passing through non-
metallic objects (doors, windows, wooden walls). However, the radio signal range is strongly reduced.
The radio transmission problems can be avoided by placing the devices on a direct propagation path.
Wireless device
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Wireless device
Wireless device
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