User manual

Digitaler Hochfrequenz Analyser HF38B
© Gigahertz Solutions GmbH, D-90579 Langenzenn Revision 2.3 Page 6
mum value. Insofar it is quite possible to
have two different readings at the exactly
same spot within 24 hours. The maximum
value across a locally defined area, however,
usually changes only if also the RF sources
change, which is why the latter value is much
more representative of the assessment of RF
exposure.
Quick Overview Measurements
Quick overview measurements are good to
gain an overall insight into the situation.
Since the actual number values are of sec-
ondary interest then, it is usually best to sim-
ply follow the audio signals that are propor-
tional to the field strengths (Set „Betrieb
(On)“ switch to:
).
Procedure:
RF analyzer and antenna are to be checked,
following the instructions under „Getting
Started.“
First set the measurement range switch to
19.99mW/m². Only if displayed measurement
values are persistently below ca. 100µW/m²,
change to the measurement range
199.9µW/m².
Set the switch „Signalbewertung (signal as-
sessment)“ to „Spitzenwert (peak value)“.
RF radiation exposure can differ at each
point and from all directions. Even though the
RF field strength of a given space changes
far more quickly than at lower frequencies, it
is neither possible nor necessary to measure
all directions at any given point.
Since this is not an accurate quantitative
measurement but a quick overview assess-
ment, the antenna can be removed from the
top end of the RF analyzer. Holding the an-
tenna at its very end, the polarization plane
(vertical or horizontal) can be easily changed
with a turn of your wrist. However, you can
just as well use the RF analyzer with the an-
tenna attached to it.
Since there is no need to look at the display
during an overview measurement but you
only listen to the audio signal, it is very easy
to slowly walk through the indoor or outdoor
spaces in question, thereby constantly mov-
ing the antenna or the RF analyzer with at-
tached antenna into each direction. This will
provide you with a quick overview of the
situation. Especially in indoor spaces, an-
tenna movements towards the ceiling or the
floor will reveal astonishing results.
As already mentioned above, overview
measurements are not meant to provide ac-
curate results, but to identify those zones
within which local peak values are found.
Quantitative Measurements
After having identified the relevant measure-
ment points, following the instructions in the
previous section, the actual testing can be-
gin.
Setting the Measurement Range
Switch setting as described under „Quick
Overview Measurements“. Basic rule for
measurement range selection: As coarse as
necessary, as fine as possible.
When the RF analyzer even goes into over-
load in the measurement range
„1999µW/m²“, a „1“ will appear at the left-
hand side of the display. In this case the
measurement values exceed the measure-
ment range of the RF analyzer. By means of
an RF damper (a miniature adapter for the
antenna socket), an accessory available from
Gigahertz Solutions, it is possible to extend
the measurement range by a factor of 100.
Signal Assessment
Note: In contrast to the average value, the
wave peak of an electromagnetic wave is re-
ferred to as peak value. This particular value
is regarded as the measure of the critical
“biological effects“ of RF radiation.
In “peak hold” mode, the peak value of the
signal can be obtained within a defined time
frame.
A lot of measuring technicians work with the
function “ peak hold “.
Procedure: Gently set the switch “signal
evaluation” to “peak hold”. This also is the
beginning of a defined time frame for the
measurement.
In the everyday measurement practice this
function has great value. The peak value is
related to the actual signal situation. This is
important because the situation is subject to
change due to of time, direction of the radia-
tion, polarization, and the points of meas-
urements being taken. Therefore it can hap-
pen that single peaks can be missed.
Someone with very much experience will be
able to obtain additional information from the
comparison between average and peak val-
ues. Basic Rule: The more the two measure-
ment values differ from one another (In 2.4-