Currently the range for my 125khz RFID reader is about 4 centimeters. I have opened it like below: Opened Reader

Is there any way to increase the range to around 10 to 20 centimeters? For example, increasing the number of turns or something. And if so, how would I do it? Thanks.

  • 2
    \$\begingroup\$ Crop the photo, man! 80% of it is irrelevant. \$\endgroup\$
    – Transistor
    Aug 25 '18 at 20:27
  • \$\begingroup\$ Take a look at how WiTricity does their range retention. \$\endgroup\$
    – winny
    Aug 25 '18 at 21:36
  • 1
    \$\begingroup\$ You likely need a much larger loop, with the same inductance. And larger tags. \$\endgroup\$ Aug 26 '18 at 1:58
  • \$\begingroup\$ you'll need a bigger coil and also more power and a more sensitive detector... it's not going to be easy. \$\endgroup\$
    – Jasen
    Aug 26 '18 at 8:48

The range of a RFID reader with a (round) coil with diameter D is approximately D/sqrt(2). So you need a (round) coil with approximativ D=15cm to get more than 10cm reading distance. But as the inductance needs to be the same, you have to reduce the winding turns of the coil accordingly. How to? The total length of the wire of the new coil needs to stay the same as with the old coil in the photo above. Also the wire thickness needs to stay the same.

  • \$\begingroup\$ You probably meant to write D=100cm for 10cm reading distance? \$\endgroup\$ Sep 4 '18 at 18:47
  • 1
    \$\begingroup\$ No, but the formula is wrong. I meant reading distance L=D/sqrt(2), which gives L=~10cm for D=15cm. \$\endgroup\$ Sep 4 '18 at 20:20
  • \$\begingroup\$ Well, you stated 'the range...is', so technically the formula is correct. I like your answer; very compact and to the point. \$\endgroup\$ Dec 26 '18 at 6:11

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