hmm, an interesting thought
i think that aliens know of our existense on this planet, and that they try not to interfere for in the past they have done so and it has brought a downfall to the planet
i mean, if aliens came to earth, landed in america, and said 'heres our technology, share it' would it really be givin equally to all parties?
this is why I think that we haven't gotten anything from them, and i mean anything, from a simple 'hey' to actual integration
as for the radio waves, they haven't gotten far at all, and are nowhere near a planet like our own capable of inhabiting life
and as for UFOs who can get the signal, they aren't looking for it or are on looking for the wrong signall
such as radio waves, being if they've found them or not, must be outdated