How far will our signals propagate through space over time?

Considering attenuation, will man's radio signals just keep going, moving farther down on the spectrum, or will they eventually meet enough resistance in space to have a limit on their range? Saw Contact recently, and it made me wonder.

Theoretically there's no limit, but statistically there is because of interference and attentuation caused by material in space, like vast clouds of gas and dust.

There is no resistance in space but there is interference. The Signal could also hit a black hole as well, there are many variables but if it had a clean path it could literally go on forever.

The only resistance that it could meet, would be the gravitational pull of another body. Whether that be a sun, planet or black hole doesn't matter. It could also be an accumulation of dark matter.

Otherwise, there is nothing to stop it.

But the real question is, if there is nothing out there to pick it up, does it really exist to begin with?

even without attenuation, the intensity of your signals will drop inversely proportional to the distance square. The signal will become very faint at large distance.