ITU-T Technical Session on EMF
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Transcript of ITU-T Technical Session on EMF
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
ITU-T Technical Session on EMF
Fryderyk LewickiITU-T SG5, Rapporteur for Q 3/5
Comparison between measurement and calculations
EMF-estimator, K.guide
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Introduction
Human exposure assessment is in responsibility of the ITU-T SG5, Question 3
ITU-T has prepared in this subject the following Recommendations:
K.52 (2000/2004), K.61 (2003/2008) K.70 (2007) K. guide – under development
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Measurement
SAR measurement human head phantom and
automatic system very important for the hand sets
manufacturers
Electric field strength measurement
broad band – cheap but with overestimation
frequency selective – more expensive and time consuming, require post processing
On site and laboratory
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Measurement
Example of the result of the frequency selective measurement
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Measurement
Example of the result
of the frequency selective
measurement
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Measurementadvantages
It takes into account all radiating sources with real parameters
It takes into account real environment (reflections, antenna supporting hardware, obstacles)
Takes into account simultaneous exposure in the real way (phase differences of the different waves are taken into account)
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Measurementadvantages
It can be done with little knowledge about radiating sources (initial measurement of the occupied spectrum is required only)
Good quality measurement equipment is accessible on the market
A life demonstration of the measurement to the interested people is possible
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Measurementdisadvantages
Measurement is not possible for the radiating sources that do not exist yet
It is difficult to take into account the time variation of the EMF (for example mobile communication)
The effect of the presence of staff and equipment on the EMF distribution has to be avoided
SAR measurements have to use phantoms that are approximations only of the human body
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Measurementdisadvantages
It is difficult to confirm and check that all the sources are operating with maximum ERP
In the multiple sources environment a post processing is required because of different limits for different operating frequencies
There is no probe covering the whole required frequency range,
Out of band emissions may lead to overestimation in the in-band measurement
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Calculations
Very easy but with big overestimation – isotropic source with maximum ERP
Far field modelSynthetic model –
On the right: example of the vertical cross-section
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Calculations
Full-wave models (MoM, FDTD etc.)Accuracy of calculation depends on the
model used and on the exactness of description of transmitting antennas
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Simultaneous exposure to multiple sources
Typical situation is presented on this chart. Radiation from the broadcasting Transmitting Stations gives higher levels then mobile Base
Stations
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Calculationsadvantages
Non existing radiating sources can be considered
The possibility to take into account the maximum possible radiation levels (ERP’s) that lead to the maximum possible exposure levels
There are many calculation methods with different level of accuracy
The calculation with high level of overestimation is very easy to use
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Calculationsadvantages
Calculation costs are lower then the cost of measurementsIt gives an opportunity to use mitigation technique if requiredIt is possible to make calculation in areas with no access
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Calculations advantages
VHF TV (ERP=125kW, h=90m), FM (total ERP=423kW, h=55m), GSM900 (ERP=1080W, h=30m), GSM1800
(ERP=1120W h=30m) Cumulative exposure [V/m]
Horizontal cross-sections: h=90 mh=55 mh=30 m
Vertical cross-section, azimuth 333°
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Calculationsdisadvantages
Very accurate results require detailed description of the radiating antennas
In most cases do not take into account the influence of reflections
Require good knowledge of the software used
Require at least basic knowledge concerning transmitting antennas
FEKO software
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Comparisonmeasurement vs. calculation
Good agreement if properly done
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Measurement vs. Calculations
Human exposure assessment may be done by measurement or calculations
Both methods have advantages and disadvantages
Both methods have similar level of uncertainty and accuracy depending on the method and equipment or software used
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Resolution 72 Measurement concerns
related to human exposure to electromagnetic fields
Recognizing that some publications about EMF
effects on health create doubt among the
population, in particular in developing countries
Resolves to invite ITU-T, in particular Study
Group 5, to expand and accelerate its work and
support
Invites to contribute actively to the work of
Study Group 5, in providing relevant and timely
information, in order to assist the developing
countries by providing information and
addressing measurement concerns related to RF
exposure
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Resolution 72
Measurement concerns related to human exposure to electromagnetic fields
Recommendation ITU-T K.guide
„Guidance on how to manage humane
exposure to EMF’s” will be written with
Resolution 72 taken into account
Current Technical Session on EMF is an
example of action in accordance with
Resolution 72
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
ITU-T Recommendation K.guide
Guidance on how to handle the problem of the human exposure assessment in order to help the user to apply existing standards
procedures how to evaluate exposure
by measurement by calculations
procedures how to show the compliance with exposure limits
this Recommendation will be written in the possibly simple way and in order to be easy to understand
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
ITU-T Recommendation K.guide
It will include examples of the results of measurements
broad band frequency selective
examples of evaluation of the exposure levels around typical radiation sources:
mobile base stations broadcasting transmission stations wireless access systems
examples of compliance evaluation for the typical cases of simultaneous exposure to multiple sources of radiation
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Recommendation ITU-T K.70
Mitigation techniques to limit human exposure to EMFs in the vicinity of radiocommunication stations
Modeling of the transmitting antennas Importance of the
Vertical Radiation Pattern (VRP) Identification of the
main source of radiation Mitigation techniques in
order to reduce radiation level – if required EMF-estimator –
software with the library of the examples of transmitting antennas
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
ITU-T SG5 takes part in standardization by
preparing Recommendations which give
appropriate guidance for administrations and
telecommunication operators and supports
developing countries (Resolution 72)
ITU activity is complementary to the works carried
out in other international standardization entities
involved in this subject
Conclusions
ITU-T Technical Session on EMFGeneva, 27 May 2009
InternationalTelecommunicationUnion
Thank you
Questions, Comments?