experimental techniques related to electromagnetic safety · • the assessment should be unbiased...

WHO-Moscow Meeting, December 6th, 2005

© Foundation for Research on Information Technologies in Society

Experimental Techniques Related to Electromagnetic Safety

Albert Romann and Niels KusterFoundation for Research on Information Technologies in Society

ETH Zurich, Switzerland

Interaction of Transmitters with the Human Body


• design (antenna, housing, internal details)

• antenna matching

• size / shape

• external objects(ear, glasses...)

• hand• position

• shell, shell thickness

• tissue parameter• H-field coupling

MTE

Phantom / HeadCurrent distributionon the antenna

SAR

& devicePosition of the device

• position



General Absorption Mechansim• the currents are predominantly induced in the tissues by

inductive coupling, i.e., they are mainly proportional to the magnetic field distribution at the skin of the user4

• main parameters determining SAR levels in the near-field:~ H2 (H = magnetic field strength at the skin)~ j2 (j = current density on antenna/enclosure)~ 1/d2 (d = distance between tissue and antenna/enclosure)~ σ (σ = conductivity of the tissue)~ f (f = frequency)

• reactive magnetic field components couple as efficiently as the radiating components

˛ strong dependence of SAR on device position with respect to head ˛ strong dependence of SAR values on handset design˛ dependence of SAR on scatterer

4Kuster et.al., IEEE Trans. on VT, Vol. 41, No.1 February 1992, pp. 17-23



Dependence on Current Distribution & Device Position

current distribution on the antenna (jantenna)• concentrated on the antenna• magnitude depends on antenna impedance

current distribution on the enclosure (jenclosure)• distribution and magnitude depends on design

and internal structures• zero to as high as antenna current

80° 90° 100° 110°touch

SAR

a

SAR(jenclosure) SAR(jantenna)

atouch

100°

jenclosurejantenna



SAR Dependence on Handset Design Modifications• antenna • current distribution on the device• driving point impedance/matching network

• secondary RF current paths/parasitic coupling

• power dissipation

˛ performance can strongly depend on various mechanical details not obviously linked to RF performance

˛ components may be changed during production and therefore routine evaluation of the RF performance should be part of any QA program, especially the spatial peak SAR, due to the possibly important legal implications

Compliance Testing Procedures


Basic Concept• definition/implementation of an open methodology which does not

underestimate the user’s exposure for the large majority of the user population neither overestimates exposure by a large extent

˛ conservative phantom (90 percentile), i.e., shap/tissue composition

• the assessment should be unbiased with respect to the phone design, i.e., high exposure in real life should result in high exposure in the test independent of the specific design and vice versa.

˛ well defined standardized anthropometric phantom and actual device positions

• high interlaboratory repeatability of the assessed spatial peak SAR values with minimal uncertainty

˛ optimized components with respect to accuracy˛ well defined procedures˛ rigorous uncertainty assessment


Experimental Tools

1975 1980 1985 1990 1995 2000 2005

[ 10 W

/kg; G

uy et a

l. ]

Temperature

1970

Diode Loaded E-Field Sensors

Vector E-Field Sensors

Optical TD-Field Sensors

[ 5 W

/kg; B

owman

n et al

. ]

[ 50W/kg; Opt T-Sensors]

[ 0.5W/kg; Burkhardt ]

[ 1W/kg; Schuderer et al. ]

[ 0.1

W/kg

; Bas

sen et

al. ]

[ 0.00

1 W/kg

; Poko

vic et

al. ]

[ 0.01

W/kg

; Sch

mid

et al

. ]

[ pse

udo vect

or; Poko

vic et

al. ]

100 cm3

[ 1E-9

W/kg

; Meie

r et a

l. ]

[ 1E-5

W/kg

; Hein

zelm

ann et

al. ]

[ 1E-5

W/kg

; Load

er et

al. ]

[ 1E-11

W/kg

; Man

n et al

. ]

[ 1E-7

A/m

√Hz;

Kram

er et

al.]

[ 10 m

A/m@

1GHz;

Pokovic

et al

. ]

10 cm3

1 cm3

0.1 cm3

0.01 cm3

1 mm3

0.1 mm3

Sensor Array

[ 0.01

W/kg

; Sch

mid

et al

. ]

Near-Field Measurement and Scanning Technology



Optimized Dosimetric Probes

© IFH - Laboratory for EMF and Microwave Electronics - ETH Zurich

ProbeCharacterization

Advanced Electromagnetic Probes for Near-Field Evaluations

Probe sizeProbe material

Sensor displacementProbe material

Spurious couplingDiode characteristicsLoading of the sensor

ReflectionsBoundary effects

Spherical isotropySpatial resolution

Line pickupProbe linearityFrequency response

Incident field

Field distortionaround the probe

Field distortioninside the probe

Field detection


Field Distortion Around the Probe(in % of the incident field at the probe tip)


mm

%

-10

0

10

20

30

40

50

-20 -10 0 10 20

80

60

40

20

0

-20

-40

-60


Field Distortion due to the Boundary(in % of the frontal incident plane wave at 900 MHz at the probe tip)

d=3mm d=1mm

%


0

2

4

6

8

10

12

14

16

18

20

5 0 5 5 0 5

0

5

10

15

20

25

0

5

10

15

20

25



Boundary Effects (in lossy liquids)

Compensation works well as long as:• the boundary curvature is small;• the probe is angled less than 30° to the boundary;• the distance between the probe and boundary is larger than 25% of the probe diameter;• the probe is symmetric.

The described compensation technique enables the reduction of boundary effect error to<3% for compliance testing with DASY3.

S=S0+Sb exp (- za) cos (π z )λ

0

5

10

15

20

25

30

35

z[mm]

SA

R[m

W/g

]/W

ET1D

ES3D

ET3D

WG

track of theelectric probe

z

0 5 10 15 20

z [mm]0 5 10 15 20 3025

track of theelectric probe

source

z

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

SA

R[m

W/g

]/W


Local Field Distortions Caused by the Substrate

ET3D


45° polarized E-field

-10 -5 0 5 10 15-15

15

10

5

0

-5

90

80

70

60

50

40

30

20

10

0

E

ER3D

ε=2.54

ε=1



overall deviation: ± 2 dB overall deviation: ± 0.25 dB

Deviation from Isotropy (half sphere)

optimized

classical design

θφ

Err

or

[dB

]

-2.50-2.00-1.50-1.00

-0.500.000.50

1.00

1.50

2.00

2.50

optimized design

Activedipole

Probe

Lossyliquid

φθ

Performance of the Optimized Dosimetric Probes

Frequency Range: - 30 MHz to 5 GHzDynamic Range:- 0.001 mW/g to 100 mW/g

Spherical Isotropy:- < ±0.3 dB

Boundary Effect:- error at 1 mm distance: 6 %- no error (< 0.1 dB) at: 4 mm

Dimensions:- dipole length: 3.0 mm- dipole offset: 2.0 mm- tip diameter: 3.9 mm (incl. cover)


Spherical Receiving Pattern

Err

or

[dB

]

φ θ

-2.5-2.0-1.5-1.0-0.50.00.51.01.52.02.5


© Schmid & Partner Engineering AG, Zurich

Isotropic H-Field Probe for Free Space Measurements

Frequency Range: - 100 MHz to 3 GHzDynamic Range:- 0.01 A/m to 2 A/m (at 1 GHz)

Spherical Isotropy:- ±0.2 dB

Dimensions:- loop diameter: 3.8 mm- tip diameter: 6.0 mm

E-field Sensitivity:- at 2.5 GHz: <5% (<10% standard PEEK tip)- at 3.0 GHz: 7% (15% standard PEEK tip)

f [MHz]

No

rmal

ized

Fre

qu

ency modified

PEEK tip

standard PEEK tip

0.6

0.7

0.8

0.9

1.0

1.1

1.2

0 500 1000 1500 2000 2500 3000

H3D



Frequency Range: 300 MHz to > 6 GHzDynamic Range: 2 V/m to > 1 kV/m

Isotropy:- spherical: < ±0.17 dB

Dimensions:- dipole length: 3 mm- tip diameter: 4 mm

Prototypes of Probes Enabling Pseudo-Vector Information

Frequency Range: 300 MHz to 3 GHzDynamic Range: 0.03 A/m to 2 A/m (at 900 MHz)

Isotropy:- spherical: < ±0.2 dB

Dimensions:- loop diameter: 3 mm- tip diameter: 4 mm

HV2DEV2D




Example:H-field over a microstrip hybrid 6dB coupler at 630 MHz

H-field magnitude H-field vector


Time-Domain Sens

State-of-the-Art Electrooptic Sensors

National Physics Laboratory (UK) & Tokin Corp. (Japan)(B. Loader, W. Liang, S. Torihata, 2001) Prototype development: (isotropic)

11 cm

Mach-Zehnder-Interferometer

6 mm

- bandwidth DC - 1 GHz- sensitivity 10 µV/m- dyn. range 150 dB- size 11 cm

- bandwidth DC - 1 GHz- sensitivity 15 mV/m (@ 30 Hz)- dyn. range 120 dB- size 6 mm


Time-Domain Senso

Modulated Light Source (VCSEL laser)Technical University of Berlin (Germany)Mann and Petermann (2002)“VCSEL-based miniaturised E-field probe with high sensitivity and optical power supply”

Development for hyperthermia applications (therefore demonstrated bandwidth only 100 MHz),remote powering of the laser with a photovoltaic cell.

- bandwidth DC - 100 MHz (not limit)- sensitivity 50 µV/ (mÃHz)- dyn. range 130 dB- size 5 mm

TD-Sensor AK, March 2005

Fiber-optic link concept

opticalfibers

laser diodeampl.

pvarray

antenna

photodetector

lightsource

* f

data processing unit

on chip

remoteunit


New outstanding features:

- electrical isolation- miniature size (2 mm)

- large frequency range (0.1-6 GHz)- amplitude and frequency information- high spatial resolution

minimal fielddisturbance

Challenges:

- low power consumption- miniature size (mm dimensions)- broadband response


Sensor head


500 µm

Circuit diagram

Miniature size: 1.25 mm x 2 mm

PVC

lase

r

R

C

Amplifier

RF inRF in

Amplifier

laser

R1

PVC

C1

Bias


Design

Probe, Electronics & Positioner Robot

pyrex glass wafer Ti marks for wafer sewing

optical outputcable

DASY DAEunit

probe withmicrostrip lines

glass tip


In Vitro Exposure Analysis

FDTD Analysis: SAR & T - Distribution (SEMCAD)

SAR T(t) t

0.1s

0.5s

1s

10s

10min

9dB/mm

linear scale, arbitrary normalization


In Vitro Exposure Analysis

Measurements & Comparison



Objectives of Sensor Array Device • borad-band and meeting flat phantom requirements• ultra fast (total time for SAR distribution, 1g, 10g: < 3s)• easy-to-use• reliable (repeatability: <0.5dB)

Value• detection of non-compliance with safety limits• detection of deviation from target antenna input power• detection of any deviation in RF performance compared to the

reference phone (e.g., antenna matching, poor contacts, shielding problems)

Application• R&D and Production Line Testing

Objectives of Sensor Array Device • borad-band and meeting flat phantom requirements• ultra fast (total time for SAR distribution, 1g, 10g: < 3s)• easy-to-use• reliable (repeatability: <0.5dB)

Value• detection of non-compliance with safety limits• detection of deviation from target antenna input power• detection of any deviation in RF performance compared to the

reference phone (e.g., antenna matching, poor contacts, shielding problems)

Application• R&D and Production Line Testing



Sensor Array • array of 16 x 8 x Y-X sensors (grid step: 15 mm)

Sensor Array • array of 16 x 8 x Y-X sensors (grid step: 15 mm)



Tissue Simulating Gel • phantom is filled with a semi-solid broad-band HSM (FCC compatible)• sensors are 4mm immersed in the HSM; thickness of cover: 2+/-0.1mm

Tissue Simulating Gel • phantom is filled with a semi-solid broad-band HSM (FCC compatible)• sensors are 4mm immersed in the HSM; thickness of cover: 2+/-0.1mm



Data Acquisition Electronics • the signal of each sensor is isolated, amplified and integrated in parallel

Data Acquisition Electronics • the signal of each sensor is isolated, amplified and integrated in parallel



First Prototype @ ISAP05 Korea First Prototype


State-of-the-Art and Future Near-Field Evaluation and Design Tools

Other R&D Needs• calibration methods• data acquisition• post processing • mechanical scanners/positioner • uncertainty analysis


Calibration Procedure

1. linearization of the dynamic response2. linearization of the frequency response3. determination of the sensitivity factors of the different sensors in

the different liquids or media4. determination of the spherical receiving pattern in the different

liquids or media (plane patterns are not sufficient!)




Dynamic Range of E-Field Probe

not compensated compensated

Sen

sor V

olt

age

[µV

]

1E-04 1E-03 1E-02 1E+00 1E+011E-01 1E+02

1.E+0

1.E+1

1.E+2

1.E+3

1.E+4

1.E+5

1.E+6

1.E+7

[mW/g]E

rro

r[d

B]

[mW/g]

-3

-2

-1

0

1

relative accuracy

not compensateddiode characteristic

compensated

1.E-04 1.E-02 1.E+00 1.E+02



Dynamic Range of 3D H-Field Probe


1E-02 1E-01 1E+00 1E+01

[A/m] (at 900MHz)

-3

-2

-1

0

1

Err

or[

dB

]

compensated

not compensateddiode characteristic

relative accuracy

1.E+0

1.E+1

1.E+2

1.E+3

1.E+4

1.E+5

1.E+6

[A/m] (at 900MHz)

Sen

sor V

olt

age

[µV

]

1E-03 1E-02 1E-01 1E+00 1E+01


Robust Setup for Precise Calibration of Dosimetric E-field Probes

Calibration Procedure for Lossy Liquids

SARV =4(Pfw-Pbw)

a b δcos2(πy

a)e(-2z/δ)

> 3δ

spacer

Pfw Pbw

z

x y

ab

lossyliquid



lossyliquid

dielectricslab

> 3δ

50mm

Pfw Pbw

z

x y

ab

Standing Waves in R9 Waveguide

10cm H2O, open WG

10cm Brain, open&shorten WG

12cm H2O, shorten WG

12cm H2O, open WG

10cm H2O, shorten WG



TE01 mode

zy

x

R22 Waveguide

55

45

35

25

5

15

E [V/m]

35

30

25

20

15

5

10

E [V/m]R9 Waveguide


DASY4

Future Requirements on Dosimetry

standard compliantspatial peak SARassessment of 2ndmaxima


PARALLEL COMPUTING: An IntroducitonEvaluation of Nokia 8310

DASY4: Spatial Peak SAR for Secondary Maxima


Overview

Research Achievements• novel probes: sensitvity: <±1µW/kg; spherical

isotropy: <±0.3dB; linearity: <±0.2dB; boundary effect: <0.1dB at 4mm; immunity against secondary modes of reception: <±0.1dB

• probe positioning: surface detector: <±0.2mm; positioner: <±0.1mm; wobbling: <±0.1mm; rotation precision: <±0.5°

• data acquisition: amplification & filtering: <±0.1dB

• new algorithms: extrapolation: <±0.15dB; cube searchand interpolation: <±0.15dB

•phantoms: provision of scientific data & rationale, development of phantoms & liquids

• test position: provision of scientific data & rationale for test position, development of holder

• calibration & verificaton: development of calibration techniques, procedures and setups (e.g., sensitivity, isotropy, spatial resolution, boundary effect, etc.) as well as of verification procedures

Dosimetric Assessment System (DASY4)


Guidelines/Regulations of Compliance Testing of MTE

Guidelines/Regulations for Compliance Testing of MTE1982 Safety Guidelines: ANSI/IEEE C95.1 (7-Watt Exclusion)1992 Publication of Interaction Mechanism (IEEE Trans VT-41)1992 Safety Guidelines: ANSI/IEEE C95.1 (revised exclusion clause)1992 Call: German Agency for Radiation Protection1992 Mandate: R&D of Compliance Procedure (MPT,D; Telekom,D...)1993 Safety Guidelines: RCR Std-38 (J)1995 Safety Guidelines: CENELEC prENV50166-1 (withdrawn 1998)1996 Call: ICNIRP (mobile communications)1997 Order: FCC USA (based on NRPB 1996/ANSI92)1998 Recommendation: ARIB Std-T56 (J)1998 Safety Guidelines: ICNIRP1998 Specifications: ES59005 (CENELEC TC211B WGMTE 95-98)1998 Order: Australia Certification Standard (Revision 4.0)1999 Harmonization Group: IEEE, CENELEC, ARIB, CHINA1999 Order: R&TTE EU Directive (law: April 8, 2000, transition: 1 year)2001 Standard: EN50360/50361 (TC211 MBS 98-00; ratified July 01)2001 Order: Japanese Gov. (summer 01; transition: 1 year)2003 Standard: IEEE Std 1528-2003 (SCC34-SC2 WG1 97-03)200X Standard: IEC TC106 (based on CENELEC, scheduled: 01)



Frequency Range:- 300 MHz to > 10 GHzDynamic Range:- 0.02 mW/g to 100 mW/g



Dimensions:- dipole length: 0.8 mm- tip diameter: 1.0 mm

E1D

Frequency Range:- 30 MHz to 4 GHzDynamic Range:- 0.001 mW/g to 100 mW/g



Dimensions:- dipole length: 3.0 mm- tip diameter: 3.9 mm (incl. cover)

ES3D



Uncertainty Assessment


Uncertainty Analysis

1NIST Technical Note TN 1297, http://physics.nist.gov/Pubs/guidelines/TN1297/tn1297s.pdf

Steps in Establishing an Uncertainty Budget1

• Assign a probability distribution and determine the standard uncertainty of each distribution.

Normal Distribution: u(xi) =uncertainty

k

Rectangular Distribution: u(xi) =ai

3

U-Shaped Distribution: u(xi) =M2

• Determine the combined standard uncertainty. uc(y) = Σ u2(xi)

• Determine the expanded uncertainty. U = k uc(y)

The level of confidence recommended by NIST for EMC testing is 95% which can be obtained with k=2.



Measurement SystemUncertainty Probability Divisor ci Standard

Value Distribution Uncertainty

Calibration ± 4.4 % normal 1 1 ± 4.4 %Axial isotropy ± 4.7 % rectangular √ 3 (1-cp)1/2 ± 1.9 %Hemisphericalisotropy ± 9.6 % rectangular √ 3 √ cp ± 3.9 %Spatial resolution ± 0.0 % rectangular √ 3 1 ± 0.0 %Boundary effect ± 5.5 % rectangular √ 3 1 ± 3.2 %Linearity ± 4.7 % rectangular √ 3 1 ± 2.7 %Detection Limit ± 1.0 % rectangular √ 3 1 ± 0.6 %Readout Electronics ± 1.0 % normal 1 1 ± 1.0 %Response Time ± 0.8 % rectangular √ 3 1 ± 0.5 %Integration Time ± 1.4 % rectangular √ 3 1 ± 0.8 %Mechanical Constrainsof Robot ± 0.4 % rectangular √ 3 1 ± 0.2 %Probe positioning ± 2.9 % rectangular √ 3 1 ± 1.7 %Extrapolation/Integration ± 3.9 % rectangular √ 3 1 ± 2.3 %

Combined Standard Uncertainty RSS ± 8.1 %



Calibration ErrorUncertainty Probability Divisor ci Standard


Incident power ± 4.5 % rectangular √ 3 1 ± 2.6 %Mismatch ± 1.0 % rectangular √ 3 1 ± 0.6 %Liquid conductivity ± 2.6 % rectangular √ 3 1 ± 1.5 %Probe positioning ± 1.0 % normal 1 1 ± 1.0 %Probe linearity ± 4.7 % rectangular √ 3 1 ± 2.7 %Field Homogeneity ± 2.4 % rectangular √ 3 1 ± 1.4 %




Test Sample RelatedUncertainty Probability Divisor ci Standard


Test Sample Positioning ± 6.0 % normal 0.893 1 ± 6.7 %Device Holder Uncertainty ± 5.0 % normal 0.844 1 ± 5.9 %Drift of Output Power ± 5.0 % rectangular √ 3 1 ± 2.9 %

Combined Standard Uncertainty RSS ± 9.4

Phantom and SetupUncertainty Probability Divisor ci Standard

Value Distribution (10-g) Uncertainty

Phantom Uncertainty ± 4.0 % rectangular √ 3 1 ± 2.3 %Liquid Conductivity (target) ± 5.0 % rectangular √ 3 0.55 ± 1.4 %Liquid Conductivity (meas.) ± 10 % rectangular √ 3 0.5 ± 2.9 %Liquid Permittivity (target) ± 5.0 % rectangular √ 3 0.5 ± 1.4 %Liquid Permittivity (meas.) ± 5.0 % rectangular √ 3 0.5 ± 1.4 %RF Ambient Conditions ± 3.0 % rectangular √ 3 1 ± 1.7 %



3divisior evaluated according to the degree of freedom veff=124divisior evaluated according to the degree of freedom veff=850.5 is the largest sensitivity for 10g average (0.6 for 1g average)


Uncertainty Budget for Dosimetric Evaluations withthe DASY System

Uncertainty Probability Standard StandardValue Distribution Uncertainty Uncertainty

(1-g) (10-g)

Measurement System RSS ± 8.1 % ± 8.1 %Test sample Related RSS ± 9.4 % ± 9.4 %Phantom and Setup RSS ± 5.4 % ± 4.8 %


Combined Uncertainty ± 13.5 % ± 13.3 %Expanded Uncertainty (k=2) ± 27.1 % ± 26.6 %


Uncertainty budget: System CheckUncertainty Probability Divisor ci ci Standard Standard

Value Distribution 1-g 10-g Unc. (1g) Unc. (10g)

Calibration ± 4.4 % normal 1 1 1 ± 4.4 % ± 4.4 %Axial isotropy ± 4.7 % rectangular √ 3 1 1 ± 2.7 % ± 2.7 %Hemisphericalisotropy ± 9.6 % rectangular √ 3 0 0 ± 0.0 % ± 0.0 %Boundary effect ± 5.5 % rectangular √ 3 1 1 ± 3.2% ± 3.2 %Linearity ± 4.7 % rectangular √ 3 1 1 ± 2.7 % ± 2.7 %Detection Limit ± 1.0 % rectangular √ 3 1 1 ± 0.6 % ± 0.6 %Readout Electronics ± 1.0 % normal 1 1 1 ± 1.0 % ± 1.0 %Response Time ± 0.0 % rectangular √ 3 1 1 ± 0.0 % ± 0.0 %Integration Time ± 0.4 % rectangular √ 3 1 1 ± 0.2 % ± 0.2 %Mechanical Constrainsof Robot ± 0.4 % rectangular √ 3 1 1 ± 0.2 % ± 0.2 %Probe positioning ± 2.9 % rectangular √ 3 1 1 ± 1.7 % ± 1.7 %Extrapolation/Integration ± 3.9 % rectangular √ 3 1 1 ± 2.3 % ± 2.3 %Dipole/Liquid Distance ± 1.0 % rectangular √ 3 1 1 ± 0.6 % ± 0.6 %Dipole Input Power ± 4.7 % rectangular √ 3 1 1 ± 2.7 % ± 2.7 %Liquid conductivity (target) ± 5.0 % rectangular √ 3 0.6 0.5 ± 1.7 % ± 1.4 %Liquid conductivity (meas.) ± 10 % rectangular √ 3 0.6 0.5 ± 3.5 % ± 2.9 %Liquid permittivity (target) ± 5.0 % rectangular √ 3 0.6 0.5 ± 1.7 % ± 1.4 %Liquid permittivity (meas.) ± 5.0 % rectangular √ 3 0.6 0.5 ± 1.7 % ± 1.4 %RF Ambient condition ± 3.0 % rectangular √ 3 1 1 ± 1.7 % ± 1.7 %

Combined Standard Uncertainty RSS ± 9.5 % ± 9.2 %



Validation and SystemCheck

• Enables verification that the system isperforming according to specifications

• Problems which are detected:- inappropriate liquid- malfunction of probe- malfunction of surface detector- evaluation problems


matched dipole(at phantom) distance

holder

spatial peak SARvs input powerspecified



Conclusions: Near-Field Probes• Diode-loaded probes have been optimized during the last decade; close

to physical limits • Breakthroughs are expected in active sensors • System prices for TD-Sensors will be higher since spectrum analyzer or

equivalent will be required• Current and expected specifications of E- and H-field probes with spatial

resolutions of better than 0.1cm3 are:Parameters Diode Loaded Sensors TD-Sensors - information: amplitude; broad-band [future: time domain; phase;

polarization (pseudo v-probe) narrow-band; full vector]- sensitivity: 1 V/m; 10 mA/m@1GHz [future: <0.01 V/m; <0.01 mA/m]- frequency range: E: 0.01-50GHz; H:0.1-3GHz [future: similar]- dynamic range: 40dB [future: 80 dB]- spherical isotropy: <0.3 dB [future: <0.3dB]- spatial resolution: < 30 mm3; 1mm3 (special cases) [future: < 1 mm3]

-> Probe performance meets the needs of any dosimetric assessments (compliance testing & bioexperiments); The needs for near-field evaluations are not satisfied yet



Conclusions: Temperature Probes• The best test equipments today enable temperature measurements in

hostile environments with the following specifications:- temperature range: 0 - 60°C [future: 0 - 100°C]- sensitivity: < 1mK [future: < 5mK]- spatial resolution: <1mg [future: <0.001 mg]- time constant: approx. 1s [future: approx. 0.14ms]

-> The precision and spatial resolution is sufficient to determine and localize thermal hotspots (e.g., in bioexperiments)



Conclusions: Scanners for Dosimetry/Near-Fields• The best test equipments today enable dosimetric measurements with a

precision of better than 1 dB:- frequency range: 30 MHz - 6 GHz [future: up to 10 GHz]- linearity : <0.2 dB for TDMA [future: <0.2dB for any mod.]- sensitivity: 1mW/kg or better [future: <0.01 mW/kg]- dynamic range: 40dB [future: 80 dB]- spatial resolution: <10mg (routine)

1mg (special cases) [future: <0.1 mW/kg]

• The precision is sufficient to determine spatial peak SAR on any mass or volume [future: contiguous tissue]

• Array scanners are accurate and conduct a flat phantom scan in <3s [future: various shapes; 3D-arrays]

• Due to the complexity of the equipment, excellent scientific and engineering knowledge is required to develop and manufacture a system.

-> The future demands more features and faster assessments; the needs of spatial resolution and accuracy are largely met



Conclusions: Testing Compliance (Basic Restrictions)• internationally recommended procedures warrant conservative

estimations of the maximum human exposure (1g & 10g) • uncertainty: <25% (best equipment only)• interlaboratory repeatability : <15% • total laboratory costs for compliance testing: ~ US$250k



AcknowledgmentAdvice Q. Balzano, Howard Bassen, Lars Bomholt, Kwok Chan, Camelia Gabriel, Luc Martens, Toshio Nojima, Katja Pokovic, Yahya Rahmat-Samii, Theodore Samaras, Thomas Schmid, Masao Taki

Support• Swiss Commission for Technology and Innovation• European Union• MMF, Belgium• MOTOROLA, USA• NOKIA, Finland• Ericsson, Sweden• T-MOBIL, Germany• ARIB, Japan• TDC SUNRISE, Switzerland• SWISSCOM, Switzerland• SPEAG, Switzerland


SEMCAD Simulation Platform

Application: Research and Optimization

LCD holder physical

CAD

holder floating holder connected

Measurement Simulation Measurement Simulation

Near-Field Sensors



H3D EF3D HV2D EV2D


Overview

Users of the DASY TechnologyGovernmentsChinese Center for Disease Control CNFederal Communications Commission USSouth African Bureau of Standards SARadio Research Laboratory KRCommunications Research Laboratory JPRadio Equip. Inspection&Certification Inst. JPBSMI TWTelecommunication Metrology Center CNDG TTI ESRadiation and Nuclear Safety Authority FI

Manufacturers & ProvidersAce Technology Corp. KRAcer Communications & Multimedia Inc.TWADT TWAlcatel Business Systems FAmphenol KRAmphenol T&M Antennas, Inc. USA-pex JPAppeal Telecom Co. Ltd. KRAuden TWAvantego SECasio JPCenturion International Inc. USCetecom ICT Services GmbH DCompal TWDigital EMC KRDoshisya JPFujitsu JPGaltronics globalGlobus Cellular Ltd. CAN

Hanwah Corp. / Telecom KRHTC TWHyundai Electr. Ind. Co. KRJQA JPKenwood JPKyocera Wireless Copr. JPKyusuyu JPLG Electronics Inc. KRLK Products Oy SFMatsushita Communications GBMCI JPMeerae Tech KRMEI JPMEL JPMoteco globalMotorola (>5) globalMurata JPNEC JPNokia Mobile Phones (> 5) globalNTT DoCoMo JPPhilips Consumer Communication FPSB Corporation Pte Ltd. SGQualcomm Inc. USQuanta TWRadio Frequency Investigation Ltd. UKSamsung Electronics Co. Ltd. (> 5) KRSanyo China AsiaSB Telcom Co. Ltd. KRSewon KRSiemens AG DESiemens AG DKSK Teletech Co. Ltd. KRSony JPSony Ericsson (> 5) global

Stock JPTDK Group Co. globalTelson Electronics Co. Ltd. KRT-Nova (former Deutsche Telekom) DToshiba JPTsuyama JPXellant Inc. IL

Universities & Test LabsIntertek Testing Services NA Inc. USNational University Singapore SGPCTest Engineering Laboratory Inc. USUnderwriters Laboratories Inc. USEMC Technologies ASNational Com. University JPUniversidad Politecnica de Cartagena SPETS Dr. Genz GmbH DCompliance Certification Services US


Isotropic E-Field Probe for Free Space Measurements

Spherical Receiving Pattern

Frequency Range: - 100 MHz to > 6 GHzDynamic Range:- 2 V/m to > 900 V/m


Boundary Effect:- error at 2.5 mm distance: 5 %- no error (< 0.1 dB) at: 6 mm

Dimensions:- dipole length: 3.0 mm- tip diameter: 8.0 mm (incl. cover)

ER3D


φE

rro

r [d

B]

θ

040

80120

160200

240280

320 020

4060

80100

120140

160-2.5-2.0-1.5-1.0-0.5

0.00.5

1.0

1.5

2.0

2.5



Experimental vs Nurmerical Procedures for Compliance Testing• spatial peak SAR values of current handsets are close to the safety

limits• SAR is strongly dependend on various electrical and mechanical

details not obviously linked to RF performance• SAR may strongly dependent on internal substructures of the device

˛ compliance can only be demonstrated by experimental means ˛ simulations cannot be alternative for compliance testing but for product

development

IPEM - Glasgow, Septeber 7th, 2005


Experimental EMF Exposure Assessments

• assessment of the EMF induced in biological tissues or bodies

-> exact distribution: numerical techniques, validation for complex transmitters

-> compliance: experimental in conservative phantoms

• assessment of the incident EMF

- near-field and standing wave

-> compliance: E- and H-field distribution (3D) with a spatial resolution of much smaller than wavelength

- quasi plane-wave conditions (angle of incident, field impedance)

-> compliance: maximum E-field in a plane

edge sourceexcitation


PARALLEL COMPUTING: An IntroducitonEvaluation of Nokia 8310

Source Modeling (cont.)




Frequency Range: - 30 MHz to 6 GHzDynamic Range:- 0.001 mW/g to 100 mW/g

Spherical Isotropy:- < ±0.5 dB


Dimensions:- dipole length: 2.8 mm- dipole offset: 1.0 mm- tip diameter: 2.5 mm (incl. cover)

ES3DminiDynamic Range of ES3Dmini Probe

1.E+0

1.E+1

1.E+2

1.E+3

1.E+4

1.E+5

1.E+6

1.E+7

0.0001 0.001 0.01 0.1 1. 10. 100.

mW/cm3

[mV

]



Performance of the Optimized E-Field Probes

Frequency Range: - 300 MHz to 40 GHzDynamic Range:- 10 V/m to > 1000 V/m


Boundary Effect:- error at 2.5 mm distance: 1 %- no error (< 0.1 dB) at: 2.5 mm


E1D

Frequency Range: - 30 MHz to 5 GHzDynamic Range:- 2 V/m to > 1000 V/m


Boundary Effect:- error at 2.5 mm distance: 3 %- no error (< 0.1 dB) at: 4.5 mm


EF3D



Mechanical fixation of sensor head


5 cm

2 cm

500 µm


Loop diameter: ¢ = 3.4 mmLNA package size: 2.0 x 1.25 mm

Evaluation of field sensitivity of sensor head

Loop


a) with short at LNA inputb) with loop at LNA input

Amplifier

laser

R1

PVC

C1C2

R2Bias S

ho

rt


- Characterization in dipole field (835 MHz)- Calibration with SPEAG H-field probe

Characterization of the loop sensor

glassfibers

loop

dipole

scan line

x


zy

dipole length

-125 -100 -75 -50 -25 0 25 50 75 100 1250

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

y [mm]

H-f

ield

[a.u

.]

SPEAG H field probeAOS, 0degAOS, 90degAOS, 180degAOS, -90deg


Optical Link RF-Field Sensor Peter Müller, June 6th, 2005

Dipole Test Bench

power laser850nm

FCPC geradschliff

powerfiber

datafiber50/125

sensorhead

Dasy 4 system forsensor mounting

New Focus detector

HACdipol

NWAHP8753E

Lab. powersupply

DC block

90%

10%

opt. coupler

opt. power meter

PC (Matlab)


ν [GHz] 0.835 2.45

ρload [dBm/Hz]

2.55-16.5 (no loop)

-140.4

ν: frequency∆ν: bandwidthg: gainρload: output power noiseH: magnetic field

¢ of loop: 3.4mmInput light: 50 mW

Output noise and link gain determine min. detectable H-field:

g [dBm/ (A/m)2]

-140.3

0.97

72 85

Characterization of the loop sensor

Sensitivity


Hmin

∆ν=

ρload

g ν( )

Hmin

nA

m⋅

1

Hz

5Mhz [email protected] GHz

0.2 mA/m


Dynamic range

fundamental

2nd order

3rd order

ν = 0.835 GHz

SFDR [dB*Hz2/3]

135SNDR [dB*Hz]

95

72

Measurement(with two-tone method, IM3 products):

ρnoise∆ν

Pout

Pin

SN

DR

SF

DR

1dB compressionpoint

ω

SNDR [dB*Hz]

SFDR [dB*Hz1/2] (2ω)

[dB*Hz2/3] (3ω, 2ω1−ω2, 2ω2−ω1)

log-log-plot

PinPinmaxmin

Definitions:

a) 1dB compression pointb) spurious products (harmonics or

intermodulation products)

0.4

0.004


Hmax

A

m

Hmin

nA

m⋅

1

Hz

3ω

2ω


Data Acquisition System



Data Acquisition Electronics (DAE)


SamplingADC

(16Bit)

Muxopt.trans.

opt.rec.

Status

Data

Downlink

Uplink

x 100

x 100

x 100

Chan. X

Chan. Z

on/offMechanical Surface Detector

Chan. Y

Collision Detector

optical

optical

x 10

x 10

x 10 LogicPower

Managment


DASY 4 Measurement Server


• 166MHz low power Pentium MMX• 32MB chipdisk and 64MB RAM• Serial link to DAE4 (with watchdog supervision)• 16 Bit A/D converter for surface detection system• Two serial links to robot (one for real-time communication supervised by watchdog)• Ethernet link to PC (with watchdog supervision)• Emergency stop relay for robot safety chain• Two expansion slots for future applications



Data Acquisition Electronics


Characteristics of Data Acquisition Electronics

• offset: 1µV• bias current: < 50 fA• dynamic range: 1µV - 300 mV• input impedance: 200 MΩ• mechanical surface and collision detector• battery operated: > 20 hours• optical down- and uplink




Free Space Calibration Procedure

Signal Generator

Attn. Attn.50 dB

PowerAmplifier

LPFilter

a)

Load

Probe

Adapter

c)

BidirectionalCoupler20 dB

Attn. Attn.

P1 P2

Cable

P3

CalibratedAttn.

Load

Probe

Adapter

b)

λ/4

Attn. Short

d)



Frequency Response

R22 WaveguideTEM Cell R26 Waveguide

f [MHz]

No

rmal

ized

Sen

siti

vity

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

0 500 1000 1500 2000 2500 3000


Frequency Range of 3D H-Field Probe


0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

0 500 1000 1500 2000 2500f [MHz]

No

rmal

ized

Sen

siti

vity

X Y Z


SAR Distribution


z(mm)

SAR

(m

W/c

m3)

/ W

0

0.5

1.0

1.5

2.0

2.5

3.0

analyticaltemperaturemeasurements

0 10 20 30 40SA

R (

mW

/cm

3) /

W0

0.5

1.0

1.5

2.0

2.5

3.0

z(mm)0 10 20 30 40

analyticalE-fieldmeasurements


1NIST Technical Note TN 1297, http://physics.nist.gov/Pubs/guidelines/TN1297/tn1297s.pdf

Uncertainty Concept1

• The components of uncertainty may generally be categorized according to the methods used to evaluate them.

Type A Evaluation: based on any valid statistical method for treating data

Type B Evaluation: typically based on scientific judgement using all of the relevant information available

Combined Standard represents the estimated standard deviation of theUncertainty: result

Expanded Uncertainty: measure of uncertainty that defines an interval about the measurement result within which the measured value is confidently believed to lie

Coverage Factor: level of confidence recommended by NIST for EMC testing is 95% (k=2)



Uncertainty Classes• assessment uncertainty

This is the uncertainty for assessment of the spatial peak SAR value in a given SAR distribution within a given phantom (e.g., head phantom). The uncertainty must be determined in such a manner that it is valid for all evaluations.

• phantom uncertaintyThis is the uncertainty of the technical setup (head phantom) with respect to the requirements defined in the standard (either standard phantom or definition of the coverage in percentage of the total user population). The uncertainty of the phantom can be assessed once, such that it is valid for all RF transmitters.

• EM source uncertaintyThis is the uncertainty of the spatial peak SAR assessed with a particular phone or a numerical representation of the phone compared to the phone produced during mass production. The uncertainty of the position with respect to the phantom can also be considered to be part of the source uncertainty.



Device Positioner

• Enables the rotation of the mountedtransmitter in spherical coordinateswhereby the rotation point is the earopening

• Easy and accurate device positioningaccording to: CENELEC, IEEE, etc.


rotationpoint


Light Beam Switch forProbe Tooling• Red LED beam-switch with 0.5 mm

beam width• Mounted on robot socket or table• Automatic probe tooling in 5 axes• Allows probe rotations with 0.1 mm

position accuracy• Allows repeatable probe positions after

changing probes (even among probeswith different dimensions)


red beam

DASY4


Evaluation According to IEEE1528, IEC62 209, etc.

experimental techniques related to electromagnetic safety · • the assessment should be unbiased...

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