At the recent, IEC TC106 meetings (October 31 – November 4th, 2016) in Hangzhou, China, new developments regarding performance evaluation and regulatory acceptance of vector array systems were presented.
Performance Validation Updated
The most important section of IEC 62209-3 - Annex D “SAR measurement system check and validation” - is now close to finalization. This section provides a procedure and comprehensive set of over 1000 tests with accurate numerical target values to empower regulators and users to thoroughly and independently evaluate the performance of vector measurement based system. The National Physical Laboratory (NPL) in London, UK, proposed a simple but convincing new criterion for the acceptance or rejection of such systems that is rigorous and easy to apply. The test is based on the maximum deviation from the target of all these measurements required for demonstrating compliance of wireless devices with SAR limits. During the meeting, Prof. Niels Kuster of ETH Zurich and the IT’IS Foundation, who led the development of this 3-year validation effort, demonstrated the feasibility of the proposed evaluation and the NPL-acceptance criteria by presenting initial results performed with SPEAG’s established DASY6 liquid SAR test system and the new cSAR3D vector SAR test system.
DASY6 V6.2 demonstrates highly accurate SAR measurements: Performance of DASY6 V6.2 assessed with dipole (in blue) and vertical planar inverted F antenna (VPIFA) (in orange) reference sources as defined in Annex D and G of the IEC 62209-3. Results show very small deviations from the calculated target: the average deviation is -0.01 dB (or 0 %) and the standard deviation is 0.2 dB (or 5 %). The maximum deviation is 0.6 dB (or 15%).
cSAR3D Flat easily passes the NPL-acceptance criteria for compliance testing with an uncertainty of less than 28%: The dipoles (in blue) and vertical planar inverted F antenna (VPIFA) (in orange) reference sources as defined in Annex D and G of the IEC 62209-3 were measured for all configurations with cSAR3D. Results show the agreement with the target values that are well within the specified uncertainty: the average deviation is -0.1 dB (or -2 %) and the standard deviation is 0.3 dB (or 7%). The maximum deviation is -1.3 dB (or -26 %).
Several independent test labs, including regulatory agencies, are now participating in studies to verify the numerical target values of the standard in order to increase the confidence into Annex D of the standard.
Acceptance of cDASY6 by FCC and other Regulators
The schedule for FCC acceptance of DASY6 that was presented during last month’s TCB workshop in Baltimore, USA, was confirmed in Hangzhou. Industry Canada clarified that only two features are missing in cDASY6 to gain acceptance. These features, i.e. the extended validation and system check features, have now been released and submitted to FCC and Industry Canada. The full documentation of Sensor Model Calibration (SMC), and other milestone for improved accuracy in SAR measurements has also been submitted. Accordingly, official acceptance of cDASY6 SW 6.2 is expected within the next few weeks.
Acceptance of cSAR3D and other Vector Array Systems for Demonstration of Compliance
The regulatory status of vector array systems was the topic of a special meeting in Hangzhou between SAR equipment manufacturers and national government agencies (FCC, ISED Canada, China Telecommunication Technology Labs, and NICT Japan). While vector array systems have started to be accepted as screening tools in special cases, it became evident that any vector array systems will only be accepted for use in test reduction, and that final highest case results will still be required to be retested using a classic liquid test system such as DASY6. The next steps will be dependent on the outcome of the interlaboratory comparison study organized by ISED Canada, the results of which will be discussed in the IEC106 meeting taking place in February 2017 in Florida.
Worldwide acceptance of vector-array systems as SAR compliance systems will likely have to wait until after the official publication of the IEC 62209-3 standard. During the IEC 106 plenary in Hangzhou, the forecast publication date was postponed to December 2019 in order to allow time for the committee to reach a consensus and to provide members with sufficient time to review and revise the draft.
The good news is that the lastest version cSAR3D V2.6 already meets the major requirements of repeatability recently proposed and passes the NPL-acceptance criteria with a good margin. ISO17025 calibration is offered as standard.
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