The common way of categorizing RFID tags is based on how they utilize power for communication between the reader and the tag.

a chip used for RFID tags. Minimally, all that is needed is the AVR and a coil, but he recommends some filtering capacitors. Depending on the size of the coil, different frequencies and ranges can ...

Here’s an open source RFID cloner design that is about the same size as a standard RFID key card. It doesn’t need a battery to capture key codes, just the magnetic field generated by an RFID ...