Andrew Nowicki <andrew@nospam.com> writes:

Making a narrow, high intensity microwave beam does not
make sense because nobody knows where and when to aim
the beam. 

Sure they do.  As a first guess, cover the planetary zones 
of the nearest million stars or so, with beams that are on
all the time  [Think of the beams as looking like a pincushion].
Modern phased array transmitters can generate this 
number of beams, and keep them focused on the stars, 
with little problem.  And this is roughly the number of stars
for which we have adequate proper motion and distance measurements.
(You need both since the star will be in a different place when the
beam gets there.)

This is something we can do with existing technology for about
$200M, for a beam bright enough that we ourselves can detect it.
And this cost will come down further as a consequence of Moore's
law.

    Lou Scheffer