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http://ww1.microchip.com/downloads/en/AppNotes/00710c.pdf
Using the documentation AN710 by Microchip, I trying to understand why... :
With a circular antenna of 13 cm (diameter) and 0.25 mm thick enamel wire.
50 turns :
# LF antenna: 6.31 V @ 125.00 kHz -/-
# LF antenna: 6.71 V @ 134.00 kHz -/-
# LF optimal: 40.28 V @ 193.55 kHz -/-80 turns : 85 turns :
# LF antenna: 40.15 V @ 125.00 kHz -/- # LF antenna: 22.42 V @ 125.00 kHz
# LF antenna: 18.53 V @ 134.00 kHz -/- # LF antenna: 10.34 V @ 134.00 kHz
# LF optimal: 40.28 V @ 126.32 kHz -/- # LF antenna: 40.15 V @ 126.32 kHz100 turns : 110 turns :
# LF antenna: 5.24 V @ 125.00 kHz -/- # LF antenna: 3.76 V @ 125.00 kHz
# LF antenna: 4.16 V @ 134.00 kHz -/- # LF antenna: 3.22 V @ 134.00 kHz
# LF optimal: 40.01 V @ 96.77 kHz -/- # LF optimal: 40.01 V @ 86.96 kHz
...why from 80 to 85 turns, there is a such a big difference of 17.43 V @ 125 kHz
and why an higher voltage gives a better read range (with 85 turns, 22.42 V, reading range is about 5 cm - with 80 turns, 40.15 V, reading range is about 6.5 cm).
To admin : please relocate my topic to http://www.proxmark.org/forum/viewforum.php?id=11 . Sorry about that.
Last edited by o0o0o0o (2013-04-20 11:07:55)
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Not being an electronics guy, I am not quite sure what is going on :
With the 80 turns :
When I am not touching the white cable of the hirose with my fingers, i get :
# LF antenna: 40.28 V @ 125.00 kHz
# LF antenna: 20.14 V @ 134.00 kHz
# LF optimal: 40.28 V @ 123.71 kHz
If I touch the white cable (it doesn't do anything when I'm touching the red one) :
# LF antenna: 27.39 V @ 125.00 kHz
# LF antenna: 11.55 V @ 134.00 kHz
# LF optimal: 40.15 V @ 117.65 kHz
And previous statement was wrong ! @ 27.39 V I get better reading range than @ 40.28 V...
Is my body acting as a capacitor or something ?
For Equation 1 of the documentation, what is the Current I through the antenna ?
Last edited by o0o0o0o (2013-04-20 08:53:42)
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