In this third segment of Chapter 2 from 'How to Cheat at Deploying and Securing RFID,' the topic is performing antenna power calculations. The entire 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.
To understand an antenna's performance, it's important to know how an antenna radiates power. For example, an isotropic (omnidirectional) antenna radiates power uniformly in all directions, whereas a directional antenna radiates power in a specific direction. The performance of an antenna related to the power it radiates can be understood in terms of three physical quantities: effective radiated power, power density, and link margin.
