We accidently sent signals out.
Interesting point Chronos.
I was giving a lecture (actually much more like a talk) the a grade six class last week on astronomy.
The subject got around to exoplanets and the possibility of intelligent life.
One of the kids asked me, "how do they send signals out into space".
I caught myself before I went off on a tangent. I smiled and said, "you all send message into space".
The mouths opened and you could have heard a pin drop.
I told them every time you text a message, use a cell phone, and most other forms of electromagnetic communication end up partially going into space.
They thought that was quite cool.
It was a grade six class so I did not get into inverse square and such.
Anyway back on the subject, when one looks at the technology change over the past decades. With the advent of more cable, fiber optics, narrow beam satellites and such, our radio signature must be diminishing.
I would venture to guess in ≈40 years or so, provided we don't inilate ourselves, our radio spectrum signature may be quite small.
If we broadcast our presence, we may have to do it intentionally rather than accidentally.
How ironic...