Gigahertz Solutions HFW35C Bedienungsanleitung Seite 13

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curate measurement!
Remarks concerning the antenna
The "semi rigid" cable has the best technical parameters in the instrument's fre-
quency range. It is designed for several hundred changes of orientation without
effects for the accuracy of the measurement. For the special design of the second
connecting cable we have a patent pending. The objective is to reduce an inherent
weakness of "simple-log.per" antenna designs made of PCB material. For radiation
incoming at an angle to the main direction normal designs pick up signals also
below the design frequency range, which can falsify the measurement. This anten-
na suppresses this by 15 to 20 dB in addition to the approx. 40 dB of the high pass
filter.
Settings of the Analyser
At first set "Range" to "1999 μW/m²". Only if there are constantly
very small readings, switch to the finer range. The basic rule is: as
coarse as necessary, as fine as possible. In the rare case of pow-
er densities beyond the designed range of the analyser ("1" dis-
played on the left hand side even in the coarsest range) they can
still be measured by inserting the attenuator DG20_G10, available
as an optional accessory, which makes the instrument less sensitive
(by a factor of 100).
Setting Signal Evaluation ("Signal"): The peak HF radiation value,
not the average value, is regarded as the measurement of critical
"biological effects" affecting the organism and to be compared to
recommended safety limits.
The average value ("RMS") of pulsed signals is often only a very
small fraction of the peak value. Nontheless it forms the basis of
most of the "official" safety limits regulations. Building biologists
consider this a trivialization.
How to execute the measurements
Hold the HF analyzer with a slightly outstretched arm, your hand
at the rear of the instrument.
For a rough first overview it is sufficient to probe for areas of higher
levels of radiation simply by following the audio signals walking
through the rooms of interest, directing the analyser everywhere and
rotating it.
Having identified the area of interest for a closer evaluation, change
the positioning of the instrument in order to analyse the actual pow-
er flux density. This is done
by pointing in all directions including upwards and down-
wards in flats to establish the main direction of the incoming radi-
ation,
by rotating the instrument around its longitudinal axis by up
°
to 90 to also find the plane of polarisation, and
by shifting the instrument in order to find the point of maxi-
mum exposure and to avoid being trapped by local cancellation
effects.
It is generally accepted to use the highest reading in the room
for comparison with limit or recommended values.
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