Dual-frequency Antenna Design for RFID Application Kin Seong Leong Auto-ID Laboratory, School of Electrical and Electronic...
Introduction <ul><li>Radio Frequency Identification (RFID) </li></ul><ul><ul><li>Enable supply chain automation. </li></ul...
Frequency Bands in RFID <ul><li>LF (<135 kHz) </li></ul><ul><li>HF (13.56 MHz) </li></ul><ul><li>UHF (860 – 960 MHz) </li>...
Frequency Band in RFID <ul><li>LF (<135 kHz) </li></ul><ul><li>HF (13.56 MHz) </li></ul><ul><li>UHF (860 – 960 MHz) </li><...
HF vs UHF
Proposal Formulation <ul><li>Merge HF and UHF </li></ul><ul><li>Dual Frequency Antenna </li></ul><ul><li>(With frequency r...
Current Technology <ul><li>Microstrip patch antenna </li></ul><ul><ul><li>Too low frequency ratio ( < 5). </li></ul></ul><...
Brain Storming <ul><li>Merging a HF antenna and an UHF antenna. </li></ul><ul><li>Idea: </li></ul><ul><ul><li>A HF multi-t...
Design Aim (1) <ul><li>Antenna impedance equals to the complement of the input impedance of the RFID chip at UHF operation...
Design Aim (2) <ul><li>A single feed antenna. </li></ul><ul><ul><li>Avoid modification on existing chip </li></ul></ul><ul...
A Simple HF RFID Antenna <ul><li>A multi-turn planar spiral antenna. </li></ul>
A Simple UHF RFID Antenna <ul><li>A dipole with matching network. </li></ul><ul><ul><li>RFID chip is usually capacitive. T...
An Initial Picture <ul><li>Feed point chosen to be at B. </li></ul>
Final Design
Final Design (1) <ul><li>Transmission line to transfer the HF coil antenna impedance to very high value (ideally open circ...
Final Design (2) <ul><li>Overlapping loops to provide high capacitance. </li></ul>Chip
Final Design (3) <ul><li>A gap to prevent the UHF antenna shorting the HF antenna. A patch on the bottom provides path for...
Final Design (4) <ul><li>DC path for rectifier circuit (some type). </li></ul>Chip
Simulation <ul><li>Using Ansoft HFSS </li></ul><ul><li>Simulated impedance (at 960 MHz): </li></ul><ul><ul><li>24 + j143 Ω...
Fabrication <ul><li>On double-sided FR4 </li></ul>
Measurement Setup SMA Connector (At the chip  location)
HF Testing <ul><li>Transmission measurement: Resonance at HF. </li></ul>
UHF Testing (1) <ul><li>Impedance measurement: Matching impedance with respect to RFID chip. </li></ul>
UHF Testing (2) <ul><li>At 960 MHz: </li></ul><ul><ul><li>50 + j135 Ω </li></ul></ul><ul><li>Balance to unbalance problem ...
Future Work <ul><li>Miniaturization. </li></ul><ul><ul><li>To fit in small objects. </li></ul></ul><ul><li>Actual testing ...
Conclusion <ul><li>a detailed design for a high  frequency ratio dual-frequency antenna. </li></ul>
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  • Hence, the natural way of thinking is to combing them so that a tag will have all the advantages offered by HF and UHF tag.
  • The 3 rd way is to merge two working antenna together, a working HF with a working UHF dipole antenna. They are merged in a way that both of them are not affecting each other. Of course the challenge includes matching network design and the single feed constraint.
  • Presentation

    1. 1. Dual-frequency Antenna Design for RFID Application Kin Seong Leong Auto-ID Laboratory, School of Electrical and Electronic Engineering, The University of Adelaide
    2. 2. Introduction <ul><li>Radio Frequency Identification (RFID) </li></ul><ul><ul><li>Enable supply chain automation. </li></ul></ul><ul><li>Item level tagging </li></ul><ul><ul><li>Each and every item has it own tag with unique ID. </li></ul></ul><ul><ul><li>Tag is usually passive. </li></ul></ul>
    3. 3. Frequency Bands in RFID <ul><li>LF (<135 kHz) </li></ul><ul><li>HF (13.56 MHz) </li></ul><ul><li>UHF (860 – 960 MHz) </li></ul><ul><li>Microwave (2.45 GHz) </li></ul>
    4. 4. Frequency Band in RFID <ul><li>LF (<135 kHz) </li></ul><ul><li>HF (13.56 MHz) </li></ul><ul><li>UHF (860 – 960 MHz) </li></ul><ul><li>Microwave (2.45 GHz) </li></ul> 
    5. 5. HF vs UHF
    6. 6. Proposal Formulation <ul><li>Merge HF and UHF </li></ul><ul><li>Dual Frequency Antenna </li></ul><ul><li>(With frequency ratio ≈ 70) </li></ul>
    7. 7. Current Technology <ul><li>Microstrip patch antenna </li></ul><ul><ul><li>Too low frequency ratio ( < 5). </li></ul></ul><ul><li>Common aperture antenna </li></ul><ul><ul><li>Dual feed point </li></ul></ul>
    8. 8. Brain Storming <ul><li>Merging a HF antenna and an UHF antenna. </li></ul><ul><li>Idea: </li></ul><ul><ul><li>A HF multi-turn coil antenna. </li></ul></ul><ul><ul><li>A UHF planar dipole. </li></ul></ul><ul><ul><li>A transmission line to separate both the above antennas. </li></ul></ul>
    9. 9. Design Aim (1) <ul><li>Antenna impedance equals to the complement of the input impedance of the RFID chip at UHF operation </li></ul><ul><ul><li>Design frequency: 960 MHz </li></ul></ul><ul><ul><li>Chip impedance: 17 - j150 Ω </li></ul></ul><ul><ul><li>Design aim: 17 + j150 Ω </li></ul></ul><ul><li>A resonance point at HF. </li></ul><ul><ul><li>Parallel resonance. </li></ul></ul><ul><ul><li>Zero reactance and infinite resistance. </li></ul></ul>
    10. 10. Design Aim (2) <ul><li>A single feed antenna. </li></ul><ul><ul><li>Avoid modification on existing chip </li></ul></ul><ul><li>Reasonable antenna size and cost. </li></ul><ul><ul><li>Not the focus of this paper. </li></ul></ul><ul><ul><li>The final design must not be larger than 14400 mm square. </li></ul></ul>
    11. 11. A Simple HF RFID Antenna <ul><li>A multi-turn planar spiral antenna. </li></ul>
    12. 12. A Simple UHF RFID Antenna <ul><li>A dipole with matching network. </li></ul><ul><ul><li>RFID chip is usually capacitive. The matching network is to transform the antenna into inductive to enable conjugate matching. </li></ul></ul>
    13. 13. An Initial Picture <ul><li>Feed point chosen to be at B. </li></ul>
    14. 14. Final Design
    15. 15. Final Design (1) <ul><li>Transmission line to transfer the HF coil antenna impedance to very high value (ideally open circuit). </li></ul>Chip
    16. 16. Final Design (2) <ul><li>Overlapping loops to provide high capacitance. </li></ul>Chip
    17. 17. Final Design (3) <ul><li>A gap to prevent the UHF antenna shorting the HF antenna. A patch on the bottom provides path for UHF operation. </li></ul>Chip
    18. 18. Final Design (4) <ul><li>DC path for rectifier circuit (some type). </li></ul>Chip
    19. 19. Simulation <ul><li>Using Ansoft HFSS </li></ul><ul><li>Simulated impedance (at 960 MHz): </li></ul><ul><ul><li>24 + j143 Ω </li></ul></ul><ul><ul><li>Very near to the target of 17 + j150 Ω </li></ul></ul><ul><li>Resonance near 13.56 Mz </li></ul>
    20. 20. Fabrication <ul><li>On double-sided FR4 </li></ul>
    21. 21. Measurement Setup SMA Connector (At the chip location)
    22. 22. HF Testing <ul><li>Transmission measurement: Resonance at HF. </li></ul>
    23. 23. UHF Testing (1) <ul><li>Impedance measurement: Matching impedance with respect to RFID chip. </li></ul>
    24. 24. UHF Testing (2) <ul><li>At 960 MHz: </li></ul><ul><ul><li>50 + j135 Ω </li></ul></ul><ul><li>Balance to unbalance problem </li></ul><ul><ul><li>BALUN needed. </li></ul></ul><ul><li>Pattern in good agreement </li></ul>
    25. 25. Future Work <ul><li>Miniaturization. </li></ul><ul><ul><li>To fit in small objects. </li></ul></ul><ul><li>Actual testing with RFID chips. </li></ul><ul><ul><li>To obtain performance (read range) measurement. </li></ul></ul>
    26. 26. Conclusion <ul><li>a detailed design for a high frequency ratio dual-frequency antenna. </li></ul>
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