Body SAR and EU. B. Derat

Transcription

1 Body SAR and EU B. Derat

2 Overview / Outline New Approach: Directive / Standards Current applicable standard IEC/EN :2010 Tablet case study Future of EU body SAR testing Maintenance of IEC IEC

3 The «New Approach» EC directives define Essential Requirements for goods placed on the market Protection of health & safety is one essential requirement Directive 1999/5/EC on Radio and Telecommunications Terminal Equipment (R&TTE) defines essential requirements for wireless products European Standardisation Organisations (CEN, CENELEC & ETSI) develop technical specifications meeting essential requirements = Harmonized Standards Demonstrating compliance with Harmonized Standards is the easiest route to demonstrate compliance of equipment with Directive 3

4 Limits and Applicable Body SAR Measurement Standard in EU Application of ICNIRP guidelines for limiting EMF exposure IEC (International Electrotechnical Commission) TC106 mandated «to prepare internationial standards on measurement and calculation to assess human exposure to electric, magnetic and electromagnetic fields» The establishment of exposure limits is out of the scope of TC106 Harmonized standard EN 50566:2013: Product standard to demonstrate compliance of radio frequency fields from handheld and body-mounted wireless communication devices used by the general public (30 MHz - 6 GHz) Refers to IEC/EN :2010 applicable to demonstrate compliance following «procedure to determine the specific absorption rate (SAR) for wireless communication devices used in close proximity to the human body (frequency range of 30 MHz to 6 GHz)» 4

5 Scope of IEC Applies to: Any wireless device transmitting EMF in the frequency range of 30 MHz to 6 GHz With intended use at a position near the human body, in the manner described by the manufacturer With radiating part(s) of the device at distances up to and including 200 mm 5

6 General Outline of an IEC SAR Measurement Standard Measurement system specifications Phantom specifications (shell & liquid) Probe requirements Scanning system specifications Device holder Calibration Validation Uncertainty estimation Protocol for SAR assessment Measurement preparation Device positioning Measurement procedure Post-processing 6

7 Phantom and Probe Requirements Phantom specifications 2 mm thick bottom surface Shell loss tangent: tan δ 0.05 Shell permittivity 4 ± 1 for f > 3 GHz < 5 for f 3 GHz Liquid depth: 150 mm 600 ± 5 mm 2,0 ± 0,2 mm 400 ± 5 mm Probe tip diameter 8 mm for f 2 GHz λ/3 for f > 2 GHz 7

8 Target Dielectric Properties Tissue equivalent liquids should yield permittivity and conductivity values within ± 10 % of the target values Frequency (MHz) Relative permittivity (ε r ) Conductivity (σ) (S/m) Formula to correct 10 g SAR when deviation of complex permittivity from targets is more than 5 % 8

9 Generic Device Procedure for generic device if not categorized otherwise SAR measurement performed for all accessible surfaces during intended use Separation distance as specified in the user instructions 25 mm If intended use is not specified, all surfaces tested directly against flat phantom (0 separation) 9

10 Specific Devices Body-worn Body supported Desktop Front-of-face Hand-held Limb-worn Clothing-integrated 10

11 Procedure for Simultaneous Multiple Transmission Procedure for devices incorporating multiple transmission modes intended to operate at separated frequencies (uncorrelated signals) Due to probe and tissue limitations, multiple transmission modes are assessed separately then combined mathematically Alternative 1: summation of peak spatial-average SAR Alternative 2: selection of highest peak spatial-average SAR Alternative 3: use of available area and zoom scans with interpolation and extrapolation Alternative 4: evaluation by full volumetric scanning No normative procedure for correlated signals (diversity, MIMO, beamforming ) IEC/EN TR

12 Informative Annexes Fast SAR testing: short introduction to faster alternatives Test reductions: low-power exclusions and reference to IEC/EN 62479:2010 Hands free kit testing: procedure for assessing SAR in the head from wired headset Procedure for hand exposure assessment Skin enhancement factor: SAR correction depending on frequency and separation to account for standing-wave in fat 12

13 EU Case Study - Tablet/Pad,10x15x0.9cm, with 3GPP, Wireless LAN & BT Falls in the category of body supported devices B. Derat, EU Body SAR, MIC MRA International Workshop, Tokyo, Japan Feb. 13 7,

14 EU Case Study - Tablet/Pad,10x15x0.9cm, with 3GPP, Wireless LAN & BT If held-to-ear use might be supported also apply head SAR testing EN/IEC :2005 Procedures accounting for P-sensors not yet standardized (maintenance) SAR for single transmission Exclusion for transmitters with nominal average output power below 20 mw (13 dbm): typically BT All other modes to be assessed If intended use is specified, each usable orientation of the device shall be tested at separation distance ( 25 mm) as defined in user instructions If intended use is not specified, all usable orientation shall be tested at 0 mm separation from flat phantom (5 facets) B. Derat, EU Body SAR, MIC MRA International Workshop, Tokyo, Japan Feb. 14 7,

15 EU Case Study - Tablet/Pad,10x15x0.9cm, with 3GPP, Wireless LAN & BT Test positions for 3GPP & WLAN: Rear, Edge 1, Edge 2, Edge 3, Edge 4 Multi-band WLAN+3GPP+BT simultaneous transmission must be assessed following one of the 4 alternatives for each test position Alternative 1: summation - most conservative but faster approach Alternative 2: most likely applicable and more accurate when antennas are distant from each other - requires point-to-point recombination of area scans and meeting of 5 % overlap condition Alternative 3: more accurate than 1 and 2 but more processing Alternative 4: most accurate but more time consuming B. Derat, EU Body SAR, MIC MRA International Workshop, Tokyo, Japan Feb. 15 7,

16 Future of IEC SAR Measurement Standards IEC MT1/62209 mandated to revise IEC Revise IEC Revise IEC Unify IEC part 1 and part 2 standards by Develop IEC B. Derat, EU Body SAR, MIC MRA International Workshop, Tokyo, Japan Feb. 16 7,

17 Activities of IEC Maintenance Phase (1/3) Large simulation study on-going from 2010 to validate tissue dielectric parameters yield conservative exposure assessment Fast SAR assessment Methods with traditional hardware Test reduction techniques Low-power exclusion Based on device total radiated power and depending on documented DUT characteristics different maths but similar general concept as Annex B (informative) of IEC Procedure for transmitter used with host device Accounting for high SAR variability depending on host device / slot locations B. Derat, EU Body SAR, MIC MRA International Workshop, Tokyo, Japan Feb. 17 7,

18 Activities of IEC Maintenance Phase (2/3) Procedure to assess multiple source exposure Guidance for devices using P-sensors FCC KDB inspired Procedure to evaluate separation distance determination for normal and rotated configurations of sensor triggering distance Procedure to evaluate sensor coverage area 3-6 GHz tissue-adapted antenna Confined loop antenna for frequencies below 300 MHz Ultra-wideband and low-frequency sources for system verification Harmonization with part 1 [from Aprel presentation] B. Derat, EU Body SAR, MIC MRA International Workshop, Tokyo, Japan Feb. 18 7,

19 Activities of IEC Maintenance Phase (3/3) Procedure to assess SAR for devices using LTE technology 1 0,95 Normalized pssar Currently drafted in the form of a Publicly Available Spec. Test positions based on IEC /-2 Use of correlation between SAR and RF conducted power Compare the SAR of the max power mode to the limit and use RF conducted power information to select additional test modes 0,9 0,85 0,8 0,75 0,7 0,65 0,6 0,55 y = 0,9481x R² = 0,8234 y = 0,9084x R² = 0,911 Normalized conducted power 0,5 0,5 0,6 0,7 0,8 0,9 1 B. Derat, EU Body SAR, MIC MRA International Workshop, Tokyo, Japan Feb. 19 7,

20 IEEE / IEC Collaboration IEEE IEEE IEEE Dual-logo Standards IEC IEC IEC B. Derat, EU Body SAR, MIC MRA International Workshop, Tokyo, Japan Feb. 20 7,

21 IEC Vector Probe Systems Faster Approaches / Different Harware Human exposure to radio frequency fields from handheld and body-mounted wireless communication devices - Human models, instrumentation, and procedures - Part 3: Vector probe systems (Frequency range of 100 MHz to 6 GHz) P-members: Australia, Germany, Finland, France, Italy, Japan, Korea, Sweden, USA [Kiminami et al., IEEE TEMC, 2008] B. Derat, EU Body SAR, MIC MRA International Workshop, Tokyo, Japan Feb. 7,

22 Main Advantages of Vector Approaches Enable advanced field interpolation / extrapolation techniques and accurate use of array systems: speed & accuracy Can be modulation independent Allow simultaneous multi-frequency transmission assessment and accurate assessment of signals with large bandwidth Enable efficient MIMO SAR assessment procedures B. Derat, EU Body SAR, MIC MRA International Workshop, Tokyo, Japan Feb. 7,

23 Conclusion Body SAR in EU standard-based and harmonization approach IEC :2010 generic Maintenance of IEC Three main work directions (1) Adapt methods and procedures to new technologies and usages (2) Increase procedure efficiency: accelerate tests / reduce testing load (3) Harmonize IEC will move (1) and (2) one step further 23

24 Acknowledgments Warm thanks to Jafar Keshvari (NOKIA), Matthias Meier (Ingenieurbüro M. Meier), Mauro Francavilla (Telecom Italia) and Michael Derby (ACB EU) whose contributions helped a lot to prepare this presentation. 24