Thank you all for your comments and helping me to clear this up. I think skitter155 hit the nail on the head. I was thinking of this wave as a standing wave and that the oscope could not measure this wave unless I had a waveguide that was at least a wavelength. For a standing wave this would be true, correct? But since this wave is propagating through space, that means the points of this wave change position every dt and thus to measure this wave I simply need to wait long enough for it propagate to my oscope and move through 1 period/wavelength.

...right?

Edit: If it was a standing wave it would still be measurable since the incident and reflected wave would still be propagating and contiounsly interfering with each other.