ITU-T Technical Session on EMF

1. ITU-T Technical Session on EMF Comparison between measurement and calculationsEMF-estimator,K.guide Fryderyk Lewicki ITU-T SG5, Rapporteur for Q 3/5 ITU-T Technical Session on EMF Geneva, 27 May 2009

2. 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 EMF Geneva, 27 May 2009

3. Measurement • SAR measurement • human head phantomand 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 EMF Geneva, 27 May 2009

4. Measurement Example of the result of the frequency selective measurement ITU-T Technical Session on EMF Geneva, 27 May 2009

5. Measurement Example of the result of the frequency selective measurement ITU-T Technical Session on EMF Geneva, 27 May 2009

6. 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 EMF Geneva, 27 May 2009

7. 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 EMF Geneva, 27 May 2009

8. 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 EMF Geneva, 27 May 2009

9. 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 EMF Geneva, 27 May 2009

10. Calculations • Very easy but with big overestimation – isotropic source with maximum ERP • Far field model • Synthetic model – On the right: example of the vertical cross-section ITU-T Technical Session on EMF Geneva, 27 May 2009

11. 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 EMF Geneva, 27 May 2009

12. 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 EMF Geneva, 27 May 2009

13. 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 EMF Geneva, 27 May 2009

14. Calculationsadvantages • Calculation costs are lower then the cost of measurements • It gives an opportunity to use mitigation technique if required • It is possible to make calculation in areas with no access ITU-T Technical Session on EMF Geneva, 27 May 2009

15. Calculationsadvantages 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] Vertical cross-section, azimuth 333° Horizontal cross-sections: h=90 m h=55 m h=30 m ITU-T Technical Session on EMF Geneva, 27 May 2009

16. 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 EMF Geneva, 27 May 2009

17. Comparisonmeasurement vs. calculation Good agreement if properly done ITU-T Technical Session on EMF Geneva, 27 May 2009

18. 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 EMF Geneva, 27 May 2009

19. Measurement concerns related to human exposure to electromagnetic fields Resolution 72 • 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 EMF Geneva, 27 May 2009

20. 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 EMF Geneva, 27 May 2009

21. 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 EMF Geneva, 27 May 2009

22. 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 EMF Geneva, 27 May 2009

23. Recommendation ITU-T K.70 Mitigation techniques to limit human exposure toEMFs in the vicinity ofradiocommunicationstations • 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 EMF Geneva, 27 May 2009

24. Conclusions • 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 ITU-T Technical Session on EMF Geneva, 27 May 2009

25. Thank youQuestions, Comments? ITU-T Technical Session on EMF Geneva, 27 May 2009