Gigahertz Solutions HFW59D Instruction Manual page 14

Made in Germany
In general, it is well accepted that exposure limit comparisons
should be based on the maximum value emitted from the di-
rection of the strongest radiation source.
To be on the safe side with exposure limit comparisons, it might
be useful to multiply the displayed value by a factor of 2, and take
the result as a basis for your comparison. This method is often
applied by building biologists in order to avoid to be assuming a
far lower exposure than realistically existent should the meter be
measuring in the lower tolerance field, taking into account, how-
ever, that this may lead to far too high values if the meter was to
be measuring in the higher tolerance area.
Quantitative Measurement:
Identification of HF inflow
As a first step eliminate sources from within the same room (e.g.
wireless LAN). Once this is completed, the remaining radiation will
originate from outside. For remedial shielding it is important to
identify those areas of all walls (including doors, windows and
window frames!), ceiling and floor, which are penetrated by the
radiation. To do this one should not stand in the centre of the
room, measuring in all directions from there, but monitor the per-
meable areas with the antenna (LogPer) directed and positioned
2
close to the wall . That is because the antenna lobe widens with
increasing frequency. In addition reflections and cancellations
inside rooms make it difficult and often impossible to locate the
"leaks" accurately. See the illustrating sketch below!
wall
right!
potentially HF-permeable
part of the wall
antenna
The uncertainty of localization with HF-antennas
The shielding itself should be defined and surveyed by a specialist
and in any case the area covered by it should be much larger than
the leak.
2
Please note: In this position the readings on the LCD only indicate relative highs
and lows that cannot be interpreted in absolute terms.
12 © Gigahertz Solutions GmbH
wall
wrong!
potentiell
durchlässiger
Bereich
antenna