Here is Part I of Chapter 3--Radio Basics For UHF RFID--from The RF in RFID: Passive UHF RFID in Practice. Written for the electrical engineer but not the RFID expert, Dr. Dobkin explains what to expect, develop, and use while implementing an RFID system.
Before we go on to the mundane tasks of introducing the relevant terminology and technology of radio, let's share a little secret, implicit but not readily apparent in the standard texts, which the author has found to considerably simplify his view of electromagnetic radiation. It goes like this: Everything radiates, but most things cancel.