JUMO 902930 Wtrans Transmitter RTD Temperature Probe with Wireless Data Transmission Operating Manual - Manual (Page 25)

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4 Probe range
4.1 General information about radio transmission
Radio signals are electromagnetic waves the signal of which will become weaker on their path
from the probe to the receiver (this is termed as path attenuation). The field strength reduces
inversely proportional in relation to the square of the distance between the probe and receiver.
In addition to this natural range restriction, a reduced range can also be the result of the follow-
ing causes:
•
Ferroconcrete walls, metallic objects and surfaces, heat insulation or windows with vapor
deposited metal layer reflect and absorb electromagnetic waves and, for this reason, a
deadspot is formed behind.
• Metal tubes, chains, etc. on the probe housing, for this reason, do not fasten any metallic
objects on the probe housing.
• Insufficient spacing between several probes, for this reason, ensure a minimum spacing of
20 cm.
• The antenna is installed at an insufficient height; install as high as possible above the floor
and ensure visual contact between the probe and receiver.
The following values are reference values concerning permeability of radio signals:
The range between the probe and the receiver is 300 m in open air and when using the antenna
wall holder for the receiver. The optimum reception can be achieved, if visual contact can be
established between the probe and receiver.
If the receiver is installed into a switch cabinet, behind concrete walls or concrete ceilings, the
antenna must always be installed with the wall holder and antenna cable for the receiver point-
ing in the direction of the probes.
Material Permeability
Wood, plaster, glass uncoated 90 to 100 %
Brickwork, press boards 65 to 95 %
Armored concrete 10 to 90 %
Metal, aluminum lamination 0 to 10 %