# Impedance match a NFC Antenna to 50 $\Omega$

I have a hard time understanding how I can impedance match a homemade nfc-antenna to 50ohm.

My antenna is designed by calculating the inductance based on the dimensions, windings and so on. R_ant is calculated the same with C_ant. So it resonate at 13.56MHz. I would now like to impenance match the antenna to a 50ohm spectrum analyser, but the calculations I have done is far off and definitely wrong. Can some one provide a good guide on this topic. I have included a schematic on the measurements I've done to verify the resonance at 13.56 MHz

simulate this circuit – Schematic created using CircuitLab

• First of all why do you need to impedance match to the SA ? Is this for measurement purposes or other ? Apr 26 at 11:36
• Are you worried about loading the system with a lower impedance ? If this is the case maybe you may choose to buffer the measurement with a higher impedance amplifier before going into the 50 Ohms SA... Apr 26 at 11:38
• 20 MHz is not a high frequency so you may obtain a suitable high impedance voltage amplifier (with no gain perhaps, but covers you frequency band) and this will not load your system ... Apr 26 at 11:40
• Otherwise a simpler means would be to use a voltage divider into the SA, but this will attenuate your signal by 30 - 60 dB if you can affod that attenuation ... Apr 26 at 11:45