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I am pretty new to NFC but I was thinking if it possible to increase the range of an passive NFC tag by attaching a power source. As per my understanding a passive tag has low range because the EM waves generated by the tag is from induction of an active NFC. Adding a power source to the passive tag will generate its own EM which I am hoping would increase the range. Can you please help me understand if i am thinking in the right direction

Regards Rwiju Pal

Rwiju Pal
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  • Exactly how are you going to add a power source to a passive tag? There are active tags available that do what you describe with batteries. – Voltage Spike Jul 14 '17 at 21:52
  • I'm voting to close this question as off-topic because what the OP describes already exists – Voltage Spike Jul 14 '17 at 21:52
  • Possible duplicate of [What can I do to increase passive HF RFID read range?](https://electronics.stackexchange.com/questions/99135/what-can-i-do-to-increase-passive-hf-rfid-read-range) – Evan Carroll Apr 30 '19 at 23:17

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If you add a battery (power source) to a passive tag you can supply energy that could be used to power the front end receiver circuit. This means that the tag is significantly more sensitive to receiving the fields generated by the "reader". Using a battery can also mean significantly more power to be able to transmit a response to the sender.

The upshot is that the distance can be increased but, is this necessarily a good thing in some (or many) applications?

Such things as powered tags exist - they are sometimes called active tags: -

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And here are the pros and cons: -

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Andy aka
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No, you cannot convert a passive RFID tag to an active tag by adding a battery.

The reason why is simple -- passive RFID tags don't transmit RF. They communicate with a reader by modulating the RF reflected by their antenna. (A typical design may have a FET which can be switched on and off to short the antenna coil.) Performing this modulation takes very little power, so it can easily be powered by energy received from the antenna.

Besides, there's nowhere to provide power. Typical ICs used in passive RFID tags only have two terminals, which are connected directly to the antenna. Connecting a battery to those terminals would prevent the IC from communicating with the antenna, and would probably destroy the IC.