Tom Ring wrote:

Radar is the best we do, but not much information is transmitted beyond
the fact that we are here, the beam is usually narrow, and the direction
varies quickly. EME is a distant 2nd, carries real information in
simple codes, the direction varies slowly, the beamwidth is usually low
(on high GHz bands it can be less than the width of the moon), and the
number of transmitters is very low.

Either one of the previous could be picked up from a fair distance, but
not likely because of the narrow angles and varying direction. And
commercial broadcasting doesn't have the ERP in any particular direction
to carry far. We live next to a very large noise source that would tend
to swamp out what we generate.

VHF and UHF emissions escalated rapidly after WWII with the
popularization of TV, and these readily penetrate the ionosphere. So
there's a sphere of such emissions radiating outward from the Earth at
the speed of light. And at the leading edge of this radiation sphere are
the McCarthy hearings and the Howdy Doody show. No wonder the ETs have
left us alone!

Roy Lewallen, W7EL