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The above suggestion is based on the fact that slightest changes
within the environment can cause rather major changes in the
power density of a locally defined area. The person who performs
the HF testing, for example, affects the exact point of the maxi-
mum value. It is quite possible to have two different readings
within 24 hours at exactly the same spot. The maximum value
across a locally defined area, however, usually only changes if the
HF sources are subject to change. This is why the latter value is
much more representative for the assessment of HF exposure.
Preliminary Notes Concerning the Antenna
The supplied logarithmic-periodic antenna (or aerial), has excep-
tional directionality. Thus it becomes possible to reliably locate
or "target" specific emission sources in order to determine their
contribution to the total HF radiation level. To know exactly the
direction from where a given HF radiation source originates is a
fundamental prerequisite for effective shielding.
The readings from the instrument's display always reflect the inte-
gral power density at the measurement location coming from the
direction the antenna is pointing at (i.e. based on the spatial inte-
gral of the "antenna lobe").
The LogPer antenna supplied is optimised for a frequency range
of 2.4 to 10 GHz. It covers the frequencies of both WLAN bands,
bluetooth, zigbee, various radar frequencies (especially also the
densely used frequency band from 8.5 to 9.5 GHz which includes
radar for the control and survey of the air and shipping traffic, as
well as further frequency bands used commercially or for military
purposes, especially for the directional radio. Critical medicals
consider these pulsed or spread spectrum modulated signals as
biologically especially harmful.
In order to avoid measurement values to be falsified by the often
dominant radiation sources from frequencies below, such as
DECT or GSM, the HFW59D is equipped with an internal high
pass filter at 2.4 GHz, causing these lower frequencies to be sup-
pressed.
Step-by-Step-Instruction to
HF-Measurement
Procedure for the Quick Overview Measurement:
The HF analyser and antenna are to be checked following the in-
structions under "Getting Started".
First set the measurement range ("Range") switch to "max". Only
if the displayed measurement values are persistently below ap-
prox. 0.10 mW/m², change to the measurement range "min"
(199.9µW/m²).
Set the "Signal" switch to "Peak"
7
© Gigahertz Solutions GmbH
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