Cecil wrote, among other things,
... With a single inductive pickup, you cannot tell
a standing-wave current from a traveling-wave current. That fact speaks
volumes.
--
73, Cecil, W5DXP

Maybe you can't, but I can. Actually, you can, too. Just move
the probe a little bit, laterally, and observe the amplitude on the O'scope
screen. If it changes, it's not a pure travelling wave.
73,
Tom Donaly, KA6RUH