What would be the best N turns, when building a simple layer antenna coil to be resonant to 134.2kHz? Based on this specifications: 1mm insulated copper wire. 4.5cm diameter. Minimum length (based on 1mm insulated wire with N turns).

Thank you in advance.

  • \$\begingroup\$ Not that it will make much difference in practice, but is it 124.3 or 134.2? \$\endgroup\$ – stevenvh Sep 14 '12 at 12:58
  • \$\begingroup\$ Sorry I messed up in the title, I mean 134.2kHz from the RFID specifications \$\endgroup\$ – Veilkrand Sep 14 '12 at 15:52

You cannot make a resonant antenna for such low frequencies with those dimensions. Just try to calculate the wavelength for that frequency.

What is normally done (e.g. for RFID applications) is a RLC circuit that resonates at that frequency. The inductance L and part of R come from the coil; C and the rest of R are added components. Energy for transmission is normally provided by switching a transistor at that frequency. Be careful of the high voltages involved.

  • \$\begingroup\$ Can you provide an example for this frecuency? In fact, this is for an RFID application \$\endgroup\$ – Veilkrand Sep 14 '12 at 16:08

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