 The combined (incident plus reflected) wave appears to be standing still on the line and is called a standing wave.The incident wave can be characterised in terms of the line's propagation constant formula_63, source voltage formula_64, and distance from the source formula_65, by

However, it is often more convenient to work in terms of distance from the load (formula_67) and the incident voltage that has arrived there (formula_68).The negative sign is absent because formula_70 is measured in the reverse direction back up the line and the voltage is increasing closer to the source.