Kjell Hansson Mild Technical Description of Mobile Telephony System and Corresponding Exposure Levels Kjell Hansson Mild National Institute for Working.

Kjell Hansson Mild

Technical Description of Mobile Telephony System and

Corresponding Exposure Levels

Kjell Hansson Mild

National Institute for Working Life, Umeåand

Örebro University

Kjell Hansson Mild

Biological effects of radiofrequency electromagnetic fields

Thermal effectsRather well investigated, associated with acute exposure, threshold values. Guidelines and limits exists, epidemiology is missing in general.

Non thermal effectsData exists on such effects, unclear if these effects also constitutes a health hazard, more research is needed on this.

Kjell Hansson Mild

Specific Absorbtion Rate, SAR

How much energy that is absorbed per unit time and unit mass

SAR is given as watt/kg, W/kg

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ICNIRP / EU

Not wanted effects for SAR > 4 W/kg

Safety factor 10 for occup exposed,gives whole body limit of

SAR < 0.4 W/kg

For general public an additional factor 5,

SAR < 0.08 W/kg

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Cataract need about 100 W/kgThe eye is about 10 gr

Safety factor 10 givesSAR 10 W/kg over 10 g contiguous tissue

General public extra 5 timeslocal SAR = 2 W/kg.This is what we call ”guidelines for mobile phones” .

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ANSI / IEEE / FCC

SAR < 0.4 W/kg Occupational exposureSAR < 0.08 W/kg General public

Part of body: Max inhomogeneity 1:20

SAR < 8 W/kg Occupational exposureSAR < 1.6 W/kg General public

1 gram tissue

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GSM 900Pulsed output power max 2WDown regulation in steps to 3 mWDuty cycle 1/8 gives max mean power 0.25 W and low mean 0.4 mW

DCS 1800Peak pulse power max 1 W, low 2 mWMax mean power 0.125 W, low mean 0.25 mW

With DTX system further reduction

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DECT

1900 MHz, peak power 250 mW, 100 Hz rep. rate

Duty cycle 1/24, mean power about 10 mW

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SARSpecific Absorption Rate (W/kg)

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peak 1 g any 1 g cube 10 g any 10 g cube4.0 2.22 1.53 1.66 0.91

Van Leeuwen et al, TNO report FEL-99-C128, 1999

Overall SAR maximum (W/kg) for the power distribution calculated for a continuous output of 0.25 W.

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GSM900 Antenna Loss Relative 2W Reference Dipole

-4.00

-2.00

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70

Tested Handsets

dB

With Sim. Hand

Without Hand

Loss Due to Hand Mean=2.64 Std=1.77

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GSM1800 Antenna Loss Relative 1W Reference Dipole

-2.00

0.00

2.00

4.00

6.00

8.00

10.00

1 3 5 7 9

11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47

Tested Handsets

d

With Sim. Hand

Without Hand

Loss Due to Hand Mean=1.90 Std=1.37

dB

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Mobile Phone Base Stations

Power balance between base station and handheld terminal

No need to use more power than the phone can send back!

However, since the base has better receiving antenna slighty more power is used by the base station than the phone.

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Electric field strength V/m

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Kjell Hansson Mild

Mobile Phone Base Stations

Short term mission within COST 244bis

346 measurements in five countries of GSM 900 and GSM 1800 bands

Power density at single frequencies varied between< 0.000001 and 13.4 mW/m2 (max 0.28% of ICNIRP)Median value 0.01 mW/m2

Max sum of all levels in the bands:<0.000001 and 47.6 mW/m2, median 0.2 mW/m2

ICNIRP values: 900 MHz 4.5 W/m2

1800 MHz 9.0 W/m2