Upload
chenoa
View
36
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Impact of Moisture Content on RFID Antenna Performance for Wood-Log Monitoring. Sohil Shahabi Ghahfarokhi, Sathyaveer Prasad, Danial Tayari University of Gävle [email protected] , [email protected] , [email protected] October 4, 2011. Presentation outline. - PowerPoint PPT Presentation
Citation preview
RFMTC11GÄVLE OCTOBER 4–5th 2011
Impact of Moisture Content on RFID Antenna Performance for Wood-Log Monitoring
Sohil Shahabi Ghahfarokhi, Sathyaveer Prasad, Danial TayariUniversity of Gävle
[email protected], [email protected], [email protected]
October 4, 2011
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
22011-10-04
Traditional Wood Supply Chain
Designated Area
CutterLogged
Area
CollectorsPiles/Stacks
of logTransport
Factory
Stamping
32011-10-04
RFID in Wood Supply Chain
Designated Area
CutterLogged
Area
CollectorsPiles/Stacks
of logTransport
Factory
RFIDRFID
42011-10-04
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.
52011-10-04
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.
Moisture content Dielectric constant Loss tangent
5% 1.8 0.08
10% 2.1 0.11
20% 3.2 0.17
30% 4.5 0.20
40% 5.3 0.19
80% 8.8 0.15
120% 12.3 0.11
62011-10-04
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.
Parameters for RFID tag performance evaluation
• RFID Antenna Parameters – Return Loss
– Directivity
– Radiation Efficiency
• RFID performance is evaluated by computing the maximum reader range
7
Max. reading range [Ref] defined using Friis transmission formula:
2011-10-04
Antenna Design• Designed in HFSS• Folded Dipole• Polyamide Casing• Operating Frequency: 867 MHZ• Dielectric Constant of wood: 3.2
82011-10-04
Simulation Results
9
Return loss of designed antenna at different dielectric constants
2011-10-04
10
Simulation ResultsRadiation efficiency vs. Directivity at different dielectric constants
2011-10-04
Reader Range Calculation
Reader Parameters (XCODEEIU9050)
Antenna Parameters (From Simulation Results)
Return Loss (ηreader)= -10 dB Radiation efficiency(Effreader)= 0.8 Directivity (Dreader) = 0 dBiTransmitted Power (Pt )=29.5dBmPolarization efficiency = 1
Return Loss (ηtag)Radiation Efficiency (Efftag)Directivity (Dtag)
112011-10-04
Max. reading range defined using Friis transmission formula:
Reader Range Calculations
εr Loss tangent
Moisture Content
ηtag
(dB)
Dtag Efftag Max. Range
(m)
%change
2.1 0.11 10% -3.7 2.23 30% 1.8 10%
3.2 0.17 20% -5.9 2.36 27% 2 -
4.5 0.2 30% -5 2.5 22% 1.78 11%
5.3 0.19 40% -4.6 2.56 22% 1.76 12%
8.8 0.15 80% -3.2 2.19 27% 1.61 20%
122011-10-04
A= Reader range for desired dielectric constant
B= Reader range for εr =3.2
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.
132011-10-04
Questions
2011-10-04 14