[addaon]

> and seemingly was blue-shifted by an amount that could make sense from an approaching craft

What do you think the natural spectrum of the Wow signal was, for determining amount of blue shift? What resolution of spectral data do you think we have on it?

[bsdetector]

Wikipedia Wow! article says it is equivalent of hydrogen line plus 10 km/s blue shift.

Even if this was a scanning beam I think we can assume it would take a lot of energy and so may be based on a simple scalable physical process. Using hydrogen to create it makes sense as it is low mass and can be replenished.