An Introduction to Device SAR Compliance Testingresource.npl.co.uk/docs/networks/electromagnetics/071129/sar_lees/lomako.pdfAn Introduction to Device SAR Compliance Testing An introduction

RFI Global Services LtdEmail: [email protected] Web: www.rfi-global.com

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An Introduction to Device SAR Compliance Testing

An introduction to the basic concepts and techniques in performing a commercial SAR test

Joe Lomako, Principal EngineerRFI-Global Services Ltd.

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Presentation Overview – What, Why and How!

• What is SAR Testing• Why do we Test• How do we Test• System Components• Commercial Aspects

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What is SAR Testing?

• Specific Absorption Rate

• A measure of the energy absorption per unit mass

• Textbook definition: “The time derivative of the incremental electromagnetic

energy absorbed by an incremental mass contained in a volume element of

given mass density”

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SAR Equation

ρσ 2ESAR =

•E=Electric Field in•σ=Conductivity of medium•ρ=Density of medium

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The SAR Test

• Automated system

• Robot positioned antenna

• ‘Phantom’ that resembles a human head or body

• Fluid dielectrically equivalent to human tissue

• All details specifically given in Test Standard

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Why do we Test?

• In the first instance, Regulatory

• 3.1(a) of the RTTE Directive

• Many standards available

• Main ones of interest

– Europe: EN50360

– FCC: OET Bulletin 65 Supp C

• Other ‘international’ standards in development

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Why do we Test?

• Regulatory

• Safety, Public concern

• Stewart report

• Diligence

• Marketing!

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How do we Test?

• Using a commercially available SAR testing system• Other methods

– Laborious– Inaccurate

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SAR Testing Systems

• Several Systems Available• RFI employs the DASY4 system• Comprises of

– Operating System– Robot – Implantable Probes– Phantom– Device positioner– Fluids

Photo courtesy of SPEAG

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Data Processing

• “mathematical averaging”• 1g and 10g averaging mass• Different standards ask for different averaging masses• Graphical display of results

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SAR SYSTEM – SOFTWARE

• Operating System

• Computer Automated

• Graphical Interface

• Mathematical Processing of Measured data

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Phantoms

• Other Phantoms• Body Mounted• Torso• Hands• Any design

• Photos courtesy of MCL

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A Typical Test

• Placement of the device

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A Typical Test

• Output and inspection of results

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Commercial Aspects

• High Cost • Maintenance• UKAS• Quality Systems• Trained and Competent Engineers• Requirement for good technical understanding• Manufacture and disposal or TEM’s

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Commercial Aspects - Overheads

• Fluids• Dipole Calibration• Dipole Purchase

– High Q dipole – single frequency• Probe Calibration• Climate Controlled room to maintain temperature and humidity• Support systems – to exercise device during test, GSM test set,

etc

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Commercial Aspects - Quality

• A very important factor!• Quality system

– Accredited to ISO 17025– Procedures– Calibration– Records– Inter lab comparison

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Commercial Aspects – Common Problems

• Keeping to schedules– Faulty Prototypes– Bespoke or new frequencies– Availability of dipoles or probe calibration

• Can always be provided but at a prohibitive cost– Test cases for devices without product standards

• Maintenance, storage and disposal of liquids• COSHH• Health and safety

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Other devices

• Non mobile devices• Not “felt” mandatory• Although in 3.1(a) of the RTTE Directive mention “safety”• New standards will address this

– Product standards– Generic Standards

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Other Devices - Examples

• FCC testing – Laptops (3 different host laptops)– PDA’s

• New Standards – namely IEC 62209-2– Devices that are handheld– Body Mounted devices– Wrist mounted devices– Ankle mounted – “tagging”

• Bespoke– Internal medical devices

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Device Compliance Testing

• Thank you for listening

• Questions?

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Disclaimer

• The application of technical information varies depending on each user’s particular circumstances. Please ensure that competent technical advice is obtained before acting on the information in this document. No representation is made or warranty given as to the accuracy of the information contained here. RFI does not accept any liability arising from reliance on the information in this document.

• If you would like further information, please contact our Marketing Department:

– Tel: +44 (0) 1256 312000

– Fax: +44 (0) 1256 312001

– E-mail:[email protected]

– Web Site:www.rfi-global.com

Documents

An Introduction to Device SAR Compliance Testingresource.npl.co.uk/docs/networks/electromagnetics/071129/sar_lees/lomako.pdfAn Introduction to Device SAR Compliance Testing An introduction