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Impact of Moisture Content on RFID Antenna Performance for Wood-Log Monitoring

Impact of Moisture Content on RFID Antenna Performance for Wood-Log Monitoring. Sohil Shahabi Ghahfarokhi, Sathyaveer Prasad, Danial Tayari University of Gävle Sohil.shahabi@gmail.com , prdsar@hig.se , danial.tayari@gmail.com October 4, 2011. Presentation outline.

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Impact of Moisture Content on RFID Antenna Performance for Wood-Log Monitoring

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  1. Impact of Moisture Content on RFID Antenna Performance for Wood-Log Monitoring Sohil Shahabi Ghahfarokhi, Sathyaveer Prasad, Danial Tayari University of Gävle Sohil.shahabi@gmail.com, prdsar@hig.se, danial.tayari@gmail.com October 4, 2011

  2. Presentation outline • Traditional wood supply chain • RFID in wood supply chain • Challenges of using RFID in wood supply chain • Effect of moisture content on the dielectric constant of wood • Parameters for RFID tag performance evaluation • Antenna design • Simulation results • Reader range calculations • Summary • Questions

  3. Traditional Wood Supply Chain Cutter Logged Area Designated Area Transport Piles/Stacks of log Collectors Stamping Factory

  4. RFID in Wood Supply Chain Cutter Logged Area Designated Area Transport Piles/Stacks of log Collectors RFID RFID Factory

  5. Challenges of using RFID in wood supply chain • The whole process should be completed 3-5 weeks. • Processing time can go up to 15 weeks during winter. • During these 15 weeks, moisture content may vary due to environmental factors like sun, rain, snow, etc., • Hence, it influences the RFID tag and reader performance.

  6. Effect of Moisture Content on the Dielectric Constant of Wood • Moisture content of wood: the weight of water expressed as a fraction ,usually a percentage, of the weight of oven dry wood. • Dielectric constant • Loss tangent Ref: G.I. Torgovnikov, Dielectric properties of wood and wood based material., Springer series in wood science, Berlin Springer-Vlg cop, 1993.

  7. Parameters for RFID tag performance evaluation • RFID Antenna Parameters • Return Loss • Directivity • Radiation Efficiency • RFID performance is evaluated by computing the maximum reader range Max. reading range [Ref] defined using Friis transmission formula: Ref: Choo, J.; Ryoo, J.; Hong, J.; , "Novel RFID tag antenna with stability to material," Antennas and Propagation Society International Symposium, 2008. AP-S 2008. IEEE , vol., no., pp.1-4, 5-11 July 2008.

  8. Antenna Design • Designed in HFSS • Folded Dipole • Polyamide Casing • Operating Frequency: 867 MHZ • Dielectric Constant of wood: 3.2

  9. Simulation Results Return loss of designed antenna at different dielectric constants

  10. Simulation Results Radiation efficiency vs. Directivity at different dielectric constants

  11. Reader Range Calculation Max. reading range defined using Friis transmission formula:

  12. Reader Range Calculations A= Reader range for desired dielectric constant B= Reader range for εr=3.2

  13. Summary Increase of moisture content decreases the resonating frequency and increases the return loss of the RFID antenna. Hence the maximum reader range decreases up to 20%. Variation of maximum reader range may increase the overall cost of the wood supply chain and also reduces the reliability.

  14. Questions

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