RF Engineering for Wireless Networks

Appendix 3 Reflection and Matching

1. Reflection Coefficients

In most of our discussion, we have assumed that radios, transmission lines, 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 signal traveling along the cable may be partially reflected by the antenna if the impedances do not match (Figure A3-1).

The ratio of the reflected signal to the incident ...