Somebody could well have been walking across a field with a 1450 MHz generator. I don't know why; maybe it was a prototype of a portable microwave-oven/Walkman mashup. If so, it was leaky, and perhaps that's why it never caught on.
What's the reasoning for this? I've seen noted that the Wow signal of 1420 MHz is near the hydrogen line frequency, and is commonly detected astrophysically.
So is the reasoning just that, if you want to send a signal, then you might choose this frequency because other civilizations will probably have detectors tuned to it?
But then the flip-side of that is that if you detect this frequency, then it's almost certainly natural origin, from the excitation of hydrogen.
We only recorded the fact of the signal's existence, without enough resolution to make out any pattern within it. If the aliens were hoping we'd decode it, they were banking on us happening to catch their signal at a very specific instant in time, never to be repeated.
Actually it’s exactly what we did with the Arecibo message, our only attempt to make contact.