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Presentation … BIOEM 2005

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Presentation … BIOEM 2005

  1. 1. Presentation – BIOEM 2005 EXPOSURE SYSTEM FOR SIMULATING GSM AND WCDMA MOBILE PHONE USAGE A. Bahr*, H. Dorn**, T. Bolz* *IMST, Kamp-Lintfort, Germany, achim.bahr@imst.de **Charité – Universitätsmedizin Berlin, Germany This work was funded by the Federal Office for Radiation Protection (BfS) within the German mobile telecommunication research (DMF) program Bahr, BIOEM 2005 1
  2. 2. Overview • Objective • Exposure setup block diagram • Exposure signals • Antenna solution • Dosimetry • SAR results • Conclusion Bahr, BIOEM 2005 2
  3. 3. Objective of the Study • DMF study „Investigation of volunteers exposed to electromagnetic fields of mobile phones“ • Analysis of possible effects on brain activity in sleep and waking • Wake outcome variables • Spontaneous EEG • Evoked and event related potentials • Cognitive functions • Sleep outcome variables • Classical sleep parameters • Quantitative parameters derived from the raw data Bahr, BIOEM 2005 Contact point: heidi.danker-hopfe@charite.de 3
  4. 4. Block Diagram of the Exposure Setup GSM WCDMA • Computer controlled double blind protocol • GSM, WCDMA and sham exposure (isolation >80 dB) • Permanent monitoring of power levels • Alarm generation and auto-switch-off in case of Bahr, BIOEM 2005 malfunctions 4
  5. 5. Exposure Signal Characteristics GSM: WCDMA: • 900 MHz • Signal generation according to [Mbonjo, 2004] • Pulse modulated carrier s(t) • 1966 MHz QPSK signal with Ton = 553 µs Toff = 4,062 ms fast power control Ton Toff t Bahr, BIOEM 2005 5
  6. 6. State of the Art Antenna Solutions Exposure setups simulating mobile phone usage • Commercially available mobile phone [Lee, 2003] • Patch antennas in a wooden mount [Huber, 2000] • Quasi-far-Field [Borbély, 1999] • Body worn antenna [Schmid, 2004] Bahr, BIOEM 2005 6
  7. 7. Antenna Specs and Intended Use Position Specifications: • Localized exposure • GSM and WCDMA coverage • Exposure times of 8 hours during day and night Dual band antenna surrounding the pinna Bahr, BIOEM 2005 7
  8. 8. Antenna Details • PCB with a PIFA type • Weight: 14 g radiator 1 mm • Total thickness: 4 mm • Free space reflection 110 mm coefficient: 4 m 40 m 0,0 m m -5,0 -10,0 • PCB covered by foam s11 [dB] -15,0 and a washable textile -20,0 cover -25,0 -30,0 500 1000 1500 2000 2500 f [MHz] Bahr, BIOEM 2005 8
  9. 9. Measurement Method • DASY4 system • SAM head inappropriate because of collapsed pinna • Tissue simulating liquids according to FCC requirements • Measurements in the flat section of SAM phantom Bahr, BIOEM 2005 9
  10. 10. Simulation Method • Empire™ software • Heterogeneous Visible human head model (AFRL) • Based on FDTD • Antenna is directly placed at the head model • FDTD grid terminated with 6 layer PML α y x Bahr, BIOEM 2005 10
  11. 11. 900 MHz Flat Phantom SAR Results Measurement Simulation • No experimental artifacts due to antenna feeding cable Bahr, BIOEM 2005 • Widespread SAR distribution 11
  12. 12. 1966 MHz Flat Phantom SAR Results Measurement Simulation • SAR maximum near the radiating element Bahr, BIOEM 2005 12
  13. 13. Flat Phantom Localized SAR Values 25 Measurement 20 Simulation SAR [W/kg] 15 10 5 0 SAR_1g SAR_10g SAR_1g SAR_10g 900 MHz 1966 MHz • 1 W antenna input power Bahr, BIOEM 2005 • 22 % max. difference measurement/simulation 13
  14. 14. Visible Human Localized SAR Values 30 25 Original position α y 20 Alpha+15° SAR [W/kg] Increased head distance: +2 mm x 15 10 5 0 SAR_1g SAR_10g SAR_1g SAR_10g 900 MHz 1966 MHz • 1 W antenna input power Bahr, BIOEM 2005 • 28 % max. positioning dependency 14
  15. 15. Conclusion • Development and Characterization of a GSM and WCDMA exposure system simulating mobile phone usage • Computer controlled double blind protocol • Permanent monitoring and auto-switch-off in case of malfunctions • Low weight and thin planar dual band antenna • Localized exposure • Enabling 8 hours exposure time during day and night • Reasonable SAR sensitivities due to changes in antenna positioning Bahr, BIOEM 2005 15

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