Well, passive RFID tags has to be inducted to work. When the induction reaches the tag, it powers itself and then the microcontroler sends a RF signal to the reader, with the product ID, rigth?
What I want to know is: what type of induction does it use? How the induction radio frequency doesn't affect the frequency generated by the tag? What's the standard protocol used by the passive RFID tags to send the product ID of themselves?