I'm losing faith in the water hole theory. Has anyone proposed putting some HF/MW LPDA (log periodic dipole array) antennas in a geostationary orbit pointed generally out away from the earth? Each antenna can feed multiple receivers, each of those receiver outputs could be digitized, compressed, sent back to earth and put on the internet somewhere. 

If we're looking for spillover from other planets' normal daily communications, I think its useful to look at how we started: spark gap transmitters, wavelengths of 200 meters and more. We've only had the ability to get above 1 GHz for about half our radio history of 100 years or so. Suppose other civilizations had better population and frequency spectrum control so they never needed to go that high?

  Alan