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[SOLVED] Increase LF antenna range

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Junior Member level 3
Dec 19, 2014
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My confusion is I have made LF antenna for 125KHz with inductance 850-900uH and 20Ohms. Antenna terminals are directly connected Module which provides frequency.

My confusion is can I increase range of LF antenna by with decreasing Resistance??? Without making change in Inductance???

More information needed. I guess your "antenna" is a RFID reader coil. To extent the range, the coil current must be increased. Reducing the coil resistance should basically work in this direction, but the effect depends on the transmitter circuit.
Hello FVM,

Yes, you are correct. I am making RFID LF antenna for 125KHz. I have made coil antenna in square shape. Its size is 35mmX25mm. Its with 900uH inductance and 21Ohm resistance. Once I tried with increasing antenna dimensions with same Inductance(900uH) and resistance(21Ohms). At that time I have good range. How does size of antenna affects in range detection?

The field strength of a reader coil decays fast beyond a certain distance, e.g. > 1d. You need to increase the coil size to achieve a larger read distance. At the same time, you'll usually increase the reader output voltage or modify the coil matching to keep the field strength.

RFID standards have a specification of reader field strength range expected for correct operation. The field strength of simple coil geometries can be easily calculated or determined with magnetic simulation tools.
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