Standing waves, SWR

[kq6qv]

If a transmission line ends in nothing (either an open or a short), 100% of the signal gets reflected back toward the source. The forward moving signal and the backward moving signal pass through each other without affecting each other. But at each point in the line the two signal voltages add together, and considering phase, some places they will subtract. The result is a stationary voltage pattern, called a standing wave, arrayed along the transmission line.

If an incomplete load (something other than 75 ohms) causes less than a 100% reflection, then the standing wave pattern doesn