XIX Sympozjum Srodowiskowe PTZE - materialy.pdf

Introduction
XIX Sympozjum PTZE, Worliny 2009
INDUCED CURRENT MEASUREMENTS
IN THE BODY OF MANPACK RADIO OPERATORS
Jaromir Sobiech, Jarosław Kieliszek
Military Institute of Hygiene and Epidemiology, Warsaw
Modern army cannot operate without huge variety of technical devices such as radars, radios or
electronic-warfare systems. Moreover there is a constant need to equip every single private with
more and more radio-gadgets which help him to better communicate with his commander, to
receive orders in the real time and collect, preserve and transmit battlefield data.
Soldiers who need to communicate only on the fireteam or squad level use transceivers of
frequency band slightly higher than cell phones. Exposition on electromagnetic fields
generated by these radios is similar to that from cell phones. It is a local exposition of body
parts in the nearness of the radio (head, hand or arm). The communication on the level of
platoon or company in the range of few kilometers is realized inter alia with manpack radios
of HF, VHF and sometimes of UHF bands.
To provide a proper communication conditions the manpack radio works with transmitted
power as big as 20 W (in comparison fireteam radios – 0,4 W). The manpack radio is used
during movement or in the trench. In both cases the operator is in the proximity of an antenna.
It means that he is exposed on electromagnetic field as high as 150 V/m.
Problem
Taking into account above mentioned conditions the electric field intensity criterion (given in
regulations [4]) limits the total transmission time of the manpack radio to less than 10 minutes
per day, what is highly insufficient. Whereas EU/ICNIRP regulations [1] suggest firstly to
measure currents induced in the body exposed on RF field, and if they exceed permissive
level, secondly to measure electromagnetic field intensities.
There are two main ways to measure these currents. One way is to use low profile platform
consisting of two parallel conductive plates isolated from each other and one located above the
other. Human is placed on the upper plate of the platform. A voltage drop on a resistor placed
between the plates provides a measure of the induced current which flows through both the
human and the meter. The second way is to use clamp-on current probe placed on the ankle.
Researchers try to give the answer which method gives a more reliable results [5]. They
concentrate their attention on comparison of both methods when experiment conditions are
changing. But they only differ ground conductivity and ground surface texture the exposed
human stands on. They do not give hints whether the height of exposed person affect the
induced current measurements. Does his silhouette and body composition matter? How big is
the difference of induced current when exposed person stands or squats near the radio?
149