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Technical Description of Mobile Telephony System and Corresponding Exposure Levels

Technical Description of Mobile Telephony System and Corresponding Exposure Levels Kjell Hansson Mild National Institute for Working Life, Umeå and Örebro University. Biological effects of radiofrequency electromagnetic fields Thermal effects

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Technical Description of Mobile Telephony System and Corresponding Exposure Levels

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  1. Technical Description of Mobile Telephony System and Corresponding Exposure Levels Kjell Hansson Mild National Institute for Working Life, Umeå and Örebro University

  2. Biological effects of radiofrequency electromagnetic fields Thermal effects Rather well investigated, associated with acute exposure, threshold values. Guidelines and limits exists, epidemiology is missing in general. Non thermal effects Data exists on such effects, unclear if these effects also constitutes a health hazard, more research is needed on this.

  3. Specific Absorbtion Rate, SAR How much energy that is absorbed per unit time and unit mass SAR is given as watt/kg, W/kg

  4. 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

  5. Cataract need about 100 W/kg The eye is about 10 gr Safety factor 10 gives SAR 10 W/kg over 10 g contiguous tissue General public extra 5 times local SAR = 2 W/kg. This is what we call ”guidelines for mobile phones” .

  6. ANSI / IEEE / FCC SAR < 0.4 W/kg Occupational exposure SAR < 0.08 W/kg General public Part of body: Max inhomogeneity 1:20 SAR < 8 W/kg Occupational exposure SAR < 1.6 W/kg General public 1 gram tissue

  7. GSM 900 Pulsed output power max 2W Down regulation in steps to 3 mW Duty cycle 1/8 gives max mean power 0.25 W and low mean 0.4 mW DCS 1800 Peak pulse power max 1 W, low 2 mW Max mean power 0.125 W, low mean 0.25 mW With DTX system further reduction

  8. DECT 1900 MHz, peak power 250 mW, 100 Hz rep. rate Duty cycle 1/24, mean power about 10 mW

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

  10. 18.00 16.00 14.00 12.00 10.00 8.00 With Sim. Hand dB Without Hand Loss Due to Hand Mean=2.64 Std=1.77 6.00 4.00 2.00 0.00 1 4 7 16 25 28 31 37 40 46 49 52 55 58 61 64 67 10 13 19 22 34 43 70 -2.00 -4.00 Tested Handsets GSM900 Antenna Loss Relative 2W Reference Dipole

  11. GSM1800 Antenna Loss Relative 1W Reference Dipole 10.00 With Sim. Hand Without Hand Loss Due to Hand Mean=1.90 Std=1.37 8.00 6.00 4.00 d 2.00 0.00 1 3 5 7 9 33 11 13 15 17 19 21 23 25 27 29 31 35 37 39 41 43 45 47 -2.00 Tested Handsets dB

  12. 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.

  13. Electric field strength V/m

  14. 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

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