Humm... Waytoowise or someone can fill me in on this, but electromagnetic radiation follows the square law: if you double the distance from the transmitter, the signal strength is not one-half, but one-quarter. Therefore, when you get far enough away, do you get down to the last photon? or maybe just keep dispersing the wavefront to the edge of the universe?
One thing for sure, the 6BQ7A cascode RF amp in Steve D's CT-100 would have long since lost the signal!