User's Manual

APPENDIX C
37
Antenna Design
Appendix C: Antenna Design
C.1 Introduction
This appendix gives an example of how you could construct an antenna to work with
the micro-reader. It also provides information about calculating the Q factor and
adapting the inductance range.
The antenna properties should be:
Q factor less than 20
Inductance between 46 and 48 µH
Recommended maximum size 200 mm x 200 mm
C.2 Antenna Construction
Item List:
Method:
- Wind 15 turns of item 1 with a diameter of 75 mm.
- Leave about 50 mm free at the ends, cross the wires (at the +/- 50 mm point)
and secure them together using the tape (item 2).
- twist the spriband (item 4) onto the coil that you have just made, leaving the
start and finish ends free.
- Strip the insulating braid back at the end of the antenna lead (item 5). Wrap
the start and finish ends at least three times around the bared ends and solder
the joints (the polarity is not important).
- Tightly bind the soldered joints to the spriband using the cloth tape (item 3).
This method should result in a 47 µH antenna with a quality factor of
approximately 17 - 18.
Item Description Quantity
1 Enamelled solid copper wire, 0.2 mm 2.1 g
2 Tape, 10 mm wide 20 mm
3 Block cloth tape, 12 mm wide 0.12 m
4 Spiroband, 3 mm diameter 0.24 m
5 Screened antenna lead 1 m