Gigahertz Solutions HF59B Instruction Manual page 6

Digital High Frequency Analyser HF59B
nature these non-pulsed sources are not
available for audio analysis. That means you
can get a significant reading on the instru-
ment without hearing any audio signal, which
makes the interpretation of the readings
more difficult. To avoid this source of misin-
terpretation the instrument marks those "in-
audible" signals by a rattling tone, the loud-
ness of which is in proportion to its share in
the total signal. The frequency of this mark-
ing is very low (16 Hertz). An example of it
can be downloaded as an MP3 file from our
home page. With the switch to the right of
the display in the "Pulse" position, these
(sources of radiation and the rattling "mark-
ing" are blanked out.
To significantly enhance the desirable sup-
pression of frequencies below 800 MHz by
the aerial itself one can use the 800 MHz high
pass filter which we offer as an extra acces-
sory. This small filter can be screwed be-
tween the aerial cable and the instrument
itself. We recommend to have it screwed
tightly to the aerial cable permanently. Below
600 MHz its dampening exceeds 40 dB
(equivalent to a factor of more than 10 000).
From 800 MHz to 600 MHz the filter curve
drops steeply.
In order to measure frequencies below 800
MHz down to 27 MHz one can use Gigahertz
Solutions active horizontally isotropic ultra
broad band aerial, the UBB27. It can be
screwed to the aerial input socket of the in-
strument.
Information concerning the UBB27 Aerial
This unit comes as an extra accessory to the
HF59B kit, but is an included accessory in
the HFE59B kit..
© Gigahertz Solutions GmbH, 90579 Langenzenn, Germany
Using the UBB27 Aerial, even frequencies
below 800 MHz can be measured reliably. It
is omni-directional antenna in the horizontal
plane. It responds to frequencies from 27
MHz onward to far beyond the upper limit of
the range of the HF59B.
LogPer or isotropic Aerial?
The selection depends on the objective of
the measurements and is clear in the follow-
ing cases:
• For frequencies below 800 MHz the UBB27
aerial is the only option.
• Also for long term data logging in most
cases, the isotropic observations make
most sense: Again UBB27.
• For a quick survey of the total immission
(that is: Total exposure to radiation) the
UBB also has clear advantages.
• However, when it comes to improve a
given situation by shielding measures, then
the location of the emmission of the radia-
tion has to be identified. To do that the
LogPer technique is definitely superior to
the isotropic measurement.
When it comes to quantify the total emission
in more detail, then one has to weigh the
pros and cons of the two approaches against
each other:
• Under typical measuring conditions, an
isotropic measurement has a broader error
band by its very nature, and the interpreta-
tion of the results is also more difficult. But
the measurement is faster and more en-
compassing.
• On the contrary the LogPer aerial offers a
higher precision and better localization for
Revision 4.5 (December 2006)
the same kind of work, and the interpreta-
tion of the results is easier. But a compre-
hensive measurement is more time con-
suming and restricted to a smaller fre-
quency band.
Up to now no reliable and affordable iso-
tropic aerials have been available. That is
why most of the current guides to measuring
techniques for biological evaluation of build-
ings consider LogPer aerials only. The new
UBB27 now offers an alternative. It remains
to be seen, how the community of experts
will respond in the next few years.
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