Planning Rf Networks; Rf Signal Range - Siemens Desigo TRA Mounting And Installation Manual

Table of Contents

Advertisement

Practical hints
46 / 56
Siemens
Building Technologies
11.5

Planning RF networks

11.5.1 RF signal range

Send RF signals are electromagnetic waves, the field strength at the receiver
decreases as the distance to the transmitter increases, in other words, the RF rang
e is limited. Any materials in the transmission field reduces the range accordingly.
RF waves do penetrate walls, but dampen the strength versus pure line of sight.
Reduction in range from walls versus a free field of view:
Material
Wood, gypsum, uncoated glass, without metal
Brick, pressboards
Reinforced cement
Metal, aluminum lamination
The geometric shape of the room
determines the RF range, since
transmission is not in the form of rays,
but rather requires a certain room
volume (ellipsoid with sender Tx and
receiver Rx in both focal points).
At 30 meter in range, the ellipsoid
center diameter is theoretically
around 10 meters (868 MHz). Narrow
hallways with large walls are
unfavorable.
The antenna setup and the distance from ceilings, floors and walls plays an
important role. Internal antennas typically have better RF properties versus flush-
mount receivers. People and objects in the room also reduce range. The generally
standard range of "30 meters in buildings" should be viewed in a differential
manner dues to the numerous influences. Planning for reserves in the range is
necessary to achieve a reliable function of the RF system, even under unfavorable
conditions.
Robust and reliable installation in buildings is achieved by ensuring
sufficient range reserves.
•  > 30 meter for very good conditions: Large free space, optimum antenna
installation and placement.
• Planning security with furniture and people in the room, through up to 5
gypsum drywall or 2 brick/aerated concrete:
– > 20 meters for transmitters and receivers with solid antenna execution and
positioning.
– > 10 meters for received installed in the room wall or corner. Or small
receives with internal antennas. Also together with switches on or wire
antenna near metal. Or narrow hallway.
• Vertical through 1-2 room corners depending on fixtures and antenna execution.
• Learning by EnOcean devices can greatly increase availability. A receiver can
work with multiple, received signals.
Mounting and installation
EnOcean RF networks
Reduction in range versus a
free field of view
0...10%
5...35%
10...90%
see Section 11.5.2
Fig: Narrow hallways with large walls.
CM111043en_03
2013-02-23

Advertisement

Table of Contents
loading

Table of Contents