Table of Contents
Advertisement
Digital High Frequency Analyser HF59B
only be detected every couple of seconds,
for a few milliseconds. This requires special
measurement technology.
The HF59B with its video bandwidth of 2
MHz provides this technology. Please use
the following procedure to ensure correct
readings:
Setting: Video bandwidth to "Tpmax". Signal
Evaluation – "Peak". With the help of the au-
dio analysis (a very short "Beep" every cou-
ple of seconds), one can clearly identify a
radar signal. With this setting and the LogPer
antenna you can identify the direction of the
source of the signal.
With the signal Evaluation switch set to
"Peak Hold" and the LogPer antenna di-
rected towards the signal emitting source.
Wait for several circles of the radar ray, move
the instrument a little left and right in order to
get the relevant maximum reading.
If the location of the radar station is unknown
it is particularly convenient to use the iso-
tropic UBB27 antenna. However the trade-off
is no information of the direction. The long
delays between pulses may consume a great
deal of time trying to detect signal direction
with a LogPer aerial.
Please note that there are Radar systems
that are operated at even higher frequencies
that can be measured with this instrument,
yet possibly not the full intensity.
Quantitative Measurement:
Identify where the radiation enters a struc-
ture
As a first step eliminate sources from within
the same room (e.g. cordless phones, wire-
© Gigahertz Solutions GmbH, 90579 Langenzenn, Germany
less routers, etc.) Once this is completed, the
remaining radiation will originate from out-
side. 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 radia-
tion. To do this one should not stand in the
centre of the room, measuring in all direc-
tions from there, but monitor the permeable
areas with the antenna (LogPer) directed and
7
positioned close to the wall
. That is because
the antenna lobe widens with increasing fre-
quency. In addition reflections and cancella-
tions inside rooms make it difficult and often
impossible to locate the "leaks" accurately.
See the illustrating sketch below!
wall
right!
wrong!
potentially HF-permeable
part of the wall
antenna
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
7
Please note: In this position the readings on the LCD
only indicate relative highs and lows that cannot be
interpreted in absolute terms.
Revision 4.5 (December 2006)
Limiting
tions and precautions
Precautionary recommentation for sleeping
areas for pulsed radiation
(Landessanitätsdirektion Salzburg, Austria)
The official regulations in many countries
specify limits far beyond the recommenda-
tions of environmentally oriented doctors,
"building biologists" and many scientific in-
wall
stitutions and also those of other countries.
They are vehemently criticised, but they are
potentiell
durchlässiger
nonetheless "official". The limits depend on
Bereich
frequencies and in the HF range of interest
here they are between 4 and 10 W/m², far
beyond 10 million times the recommenda-
tions. Official limits are determined by the
potential heat generation in the human body
and consequently measurements of averages
rather than peaks. This ignores the state of
environmental medicine. The "official" limits
are far beyond the range of this instrument,
which is optimized for accurate measurement
of power densities targeted by the building
biologists.
The standard SBM 2003 cited above classi-
fies power densities of below 1µW/m² as "no
anomaly" for non pulsed radiation in sleeping
areas, and for pulsed radiation one tenth of
that.
The "Bund fuer Umwelt und Naturschutz
Deutschland e. V." (BUND) proposes 100
values,
recommenda-
Below 0.1 µW/m²
(SBM 2003)
below 1 µW/m²
Page 11
Advertisement
Table of Contents
