[ggm]

We've been broadcasting at quite detectable volume for "contact" (sagan) 100 light- years in a radiating spherical radius. We didn't even have to argue about it.

Beaconing, assumes random dice throw (of who to beacon at) pays off. I'd say the odds are worse than lotto winning: Higher input costs, lower chance of success.

[XorNot]

You don't need to though: directed radio can be switched to point at different targets. In fact this would be preferable: i.e. blinking prime numbers out into the universe could be by switching radio targets to create the message.

[ggm]

Again, you assume that point-source RF which beacons to many places by switching aligns with when they're looking. You have to do a LOT Of hand waving around "better wiser Aliens can listen everywhere all the time" for this to pay off, and I would observe if this is such a brilliant technique, how come we haven't received the beams sent to us?