If you've ever encountered the acronym VSWR, our anchor Principal (Micro-Coax / Carlisle IT) explained the definition in regards to transmission lines. See Jim Alexander's original post on the Carlisle IT blog
(n): Voltage Standing Wave Ratio
A ratio which helps define performance for a microwave transmission line, VSWR is a specification used
to convey how well a device will transfer an incident signal. We use VSWR to show how well the
impedance is matched along a cable assembly.
In a transmission line, coaxial or otherwise, the ratio of maximum voltage to minimum voltage in the standing wave pattern is referred to as VSWR. Low VSWR (1:1) correlates with a low reflection coefficient – this is a perfect match.
Conversely, infinite VSWR would denote an open circuit or short in the circuit. Standing waves are considered troublesome and avoided in many RF designs, but can be found in many modern day applications – for example, microwave ovens and guitars utilize stnading waves and are beneficial in these instances.