Texas Instruments 2000 LF Series, Application Note, Page: 4 / 38

Lit Number: 11-06-21-068
Figure 2. MicroReader Antenna (47 µH)............................................................................ 4
Figure 3. Mini-RFM Antenna (116 µH) ............................................................................... 5
Figure 4. The RFM-104B RF Module.................................................................................. 6
Figure 5. Inductance Fine-Tuning ..................................................................................... 6
Figure 6. RFM-003B and RFM-007B Modules ................................................................... 7
Figure 7. Capacitance Fine-Tuning ................................................................................... 7
Figure 8. RFM-008B RF Module and ACC-008A Tuning Board ....................................... 8
Figure 9. The MicroReader ................................................................................................ 8
Figure 10. “ADU.EXE” Screen .......................................................................................... 10
Figure 11. LCR Meter ........................................................................................................ 10
Figure 12. High Q Vs. Low Q ............................................................................................ 11
Figure 13. LF System Spectrum....................................................................................... 11
Figure 14. Spectrum Analyzer Screen ............................................................................. 12
Figure 15. Litze Wire (3 sizes) .......................................................................................... 14
Figure 16. ‘Jumbo’ Oxygen Free Hi-Fi Wire..................................................................... 15
Figure 17. Road Loop Wire............................................................................................... 15
Figure 18. Transformer Wire ............................................................................................ 16
Figure 19. Reading Range Reduction due to Noise........................................................ 16
Figure 20. Windings Vs. Inductance ................................................................................ 17
Figure 21. Single Loop Vs. 27 µH Inductance ................................................................. 17
Figure 22. Out of Tune Conditions................................................................................... 18
Figure 23. Polypropylene Capacitor De-rating................................................................ 20
Figure 24. Polypropylene capacitors (0.01 µF & 0.47 µF) ............................................... 20
Figure 25. Antenna Tail Construction.............................................................................. 21
Figure 26. Ferrite Cored Antenna..................................................................................... 22
Figure 27. Field Lines ....................................................................................................... 23
Figure 28. Antenna Field patterns.................................................................................... 23
Figure 29. Opposing Antennas (In-phase)....................................................................... 24
Figure 30. Two 54 µH Antennas Connected in Parallel (In-Phase) ................................ 24
Figure 31. Opposing Antennas (out-of-phase)............................................................... 25
Figure 32. Two 54 µH Antennas connected in Parallel (out-of-phase) .......................... 25
Figure 33. Noise Canceling Antenna ............................................................................... 26
Figure 34. MicroReader Antenna 1 .................................................................................. 28
Figure 35. MicroReader Antenna 2 .................................................................................. 28
Figure 36. MicroReader Antenna 3 .................................................................................. 29
Figure 37. MicroReader Antenna 4 .................................................................................. 30
Tables
Table 1. RF Module Antenna Characteristics.................................................................. 9
Table 2. External Capacitance Values ............................................................................. 19
Table 3. MicroReader Antenna Designs .......................................................................... 27