Paolo Gemma, Senior Expert, Huawei paolo.gemma@huawei.com ITU Workshop on “Specific Absorption Rate (SAR) Measurement” (Cotonou, Benin, 19 July 2012) How SAR may be used with base stations with some reference to IEC 62232 Paolo Gemma, Senior Expert, Huawei paolo.gemma@huawei.com Cotonou, Benin, 19 July 2012

Regulatory aspect of SAR Measurement aspect Summary Regulatory aspect of SAR Measurement aspect Laboratory On field Simulation ITU recommendations IEC Standards Cotonou, Benin, 19 July 2012

Regulatory aspect of SAR The SAR value are used for health regulatory aspect as protection of population health. This is a factor normally linked to sites and not to equipment The majority of countries use limits for SAR published by recognized International organization ICNIRP. In some countries the SAR is used also for equipment regulatory aspect Cotonou, Benin, 19 July 2012

The ICNIRP limits of SAR Cotonou, Benin, 19 July 2012

The ICNIRP reference values Cotonou, Benin, 19 July 2012

SAR or reference Value? Cotonou, Benin, 19 July 2012

The SAR measurement from ICNIRP is the absolute measure of the effect SAR measurement require the use of phantom to simulate the human body of part of the body. For mobile communication frequency bands, SAR is usually the exposure metric to consider. Cotonou, Benin, 19 July 2012

SAR Measurement (2) Compliance assessments based on SAR are in general required for RF sources used close to the body (see EN 50383, IEC 62232, IEC 62209-1, IEC 62209-2, and EN 50413). SAR measurements are mainly conducted by specialized laboratories, since the measurements are complex and require special equipment. SAR measurement methodologies make use of phantoms simulating the human head or body which have been developed to provide conservative results with respect to exposure in real humans Cotonou, Benin, 19 July 2012

Reference value verification When the SAR verification is not possible due to the nature of the radio site. Then normally the reference limits are used and conformance to these limits is verified with different methodologies On field test Simulation Cotonou, Benin, 19 July 2012

On field Measurement advantages 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) Details in paragraphs 2 to 6. While some may think that the past is the past, wisdom is also what we learn from the past. These paragraphs make interesting reading and should be kept in mind to avoid repeating the same mistakes ITU-T Technical Session on EMF Geneva, 27 May 2009

Measurement advantages 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 Details in paragraphs 2 to 6. While some may think that the past is the past, wisdom is also what we learn from the past. These paragraphs make interesting reading and should be kept in mind to avoid repeating the same mistakes ITU-T Technical Session on EMF Geneva, 27 May 2009

Measurement disadvantages 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 Details in paragraphs 2 to 6. While some may think that the past is the past, wisdom is also what we learn from the past. These paragraphs make interesting reading and should be kept in mind to avoid repeating the same mistakes ITU-T Technical Session on EMF Geneva, 27 May 2009

Measurement disadvantages 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 Details in paragraphs 2 to 6. While some may think that the past is the past, wisdom is also what we learn from the past. These paragraphs make interesting reading and should be kept in mind to avoid repeating the same mistakes ITU-T Technical Session on EMF Geneva, 27 May 2009

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 Details in paragraphs 2 to 6. While some may think that the past is the past, wisdom is also what we learn from the past. These paragraphs make interesting reading and should be kept in mind to avoid repeating the same mistakes ITU-T Technical Session on EMF Geneva, 27 May 2009

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 Details in paragraphs 2 to 6. While some may think that the past is the past, wisdom is also what we learn from the past. These paragraphs make interesting reading and should be kept in mind to avoid repeating the same mistakes ITU-T Technical Session on EMF Geneva, 27 May 2009

Calculations advantages 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 Details in paragraphs 2 to 6. While some may think that the past is the past, wisdom is also what we learn from the past. These paragraphs make interesting reading and should be kept in mind to avoid repeating the same mistakes ITU-T Technical Session on EMF Geneva, 27 May 2009

Calculations advantages 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 Details in paragraphs 2 to 6. While some may think that the past is the past, wisdom is also what we learn from the past. These paragraphs make interesting reading and should be kept in mind to avoid repeating the same mistakes ITU-T Technical Session on EMF Geneva, 27 May 2009

Calculations disadvantages 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 Details in paragraphs 2 to 6. While some may think that the past is the past, wisdom is also what we learn from the past. These paragraphs make interesting reading and should be kept in mind to avoid repeating the same mistakes FEKO software ITU-T Technical Session on EMF Geneva, 27 May 2009

Comparison measurement vs. calculation Good agreement if properly done Details in paragraphs 2 to 6. While some may think that the past is the past, wisdom is also what we learn from the past. These paragraphs make interesting reading and should be kept in mind to avoid repeating the same mistakes ITU-T Technical Session on EMF Geneva, 27 May 2009

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 Details in paragraphs 2 to 6. While some may think that the past is the past, wisdom is also what we learn from the past. These paragraphs make interesting reading and should be kept in mind to avoid repeating the same mistakes ITU-T Technical Session on EMF Geneva, 27 May 2009

ITU Recommendations on EMF K.52 Guidance on complying with limits for human exposure to electromagnetic fields K.70 Mitigation techniques to limit human exposure to EMFs in the vicinity of radiocommunication stations. K.83 Monitoring of EMF levels K.91 Guidance for assessment, evaluation and monitoring of human exposure to radio frequency electromagnetic fields Cotonou, Benin, 19 July 2012

IEC 62232 (1) Determination of RF field strength and SAR in the vicinity of radiocommunication base stations for the purpose of evaluating human exposure. Different methodologies considered: RF field strength SAR measurement Computation methodologies guidance on their applicability on in situ evaluation of installed RBS laboratory-based evaluations; Cotonou, Benin, 19 July 2012

IEC 62232 (2) 1) product conformity: to establish that a RBS conforms to a defined set of limit conditions under its intended use; 2) compliance boundary: to establish the compliance boundary or boundaries for a RBS in relation to a defined set of limit conditions; 3) to evaluate RF field strength or SAR values at one or more evaluation locations, namely: i) evaluation location(s) at arbitrary locations outside the control boundary to provide information for interested parties; ii) evaluation location(s) at the control boundary to confirm validity of control boundary; iii) evaluation location(s) within the control boundary with the specific conditions relevant to investigate an alleged over-exposure incident; Cotonou, Benin, 19 July 2012

merci beaucoup pour votre attention Cotonou, Benin, 19 July 2012