Here is the second segment of Chapter 2 from 'How to Cheat at Deploying and Securing RFID.' The chapter--The Physics of RFID--provides a basic understanding of the physics of RFID communications and the characteristics that affect system performance during the journey of an RF wave.
Communication is basically the transfer of information--that is, to send information from one location and to receive it at another. In the RF world, this is accomplished by the transfer of energy (which contains the information coded in it) through RF waves. There are two main communication techniques that the RFID readers and tags use to communicate with each other. These techniques are coupling and backscattering.
