The RF in RFID, 2nd Edition

Appendix 4

Reflection and Matching

A4.1 Reflection Coefficients

In most of our discussion, we have assumed that radios, tags, and antennas are all well-matched, so that any power coming from one goes into the other. What happens when this is not the case? How do we measure the deviation from ideality, and what can we do about it? In this appendix we provide a very brief introduction into reflection coefficients and impedance matching.

In Microwave Land, a port is a connection from one microwave environment to another—for example, from a cable to an antenna. The cable, or any other signal-carrying electrical connection whose properties are well-defined and don’t change along its length, is often known as a transmission line. A signal traveling along ...