QUOTE (tty @ Dec 17 2007, 12:36 PM)
As a matter of fact it had been done a couple of years earlier by the germans while experimenting with the "Würzburg Riese" radar, though nobody outside Germany may have known that in 1946. And if that seems unlikely, then remember that radio astronomy got started in several countries (including Sweden) by using surplus Würzburg antennas which were large and very high quality parabolics.
Come to think of it, there have been hints that the Moon was picked up when just above the horizon (and registered at some worrying, deeply aliased distance) by radar systems of several nations late in World War II. Anybody have more details?
IIRC, the Dutch group did their first detection of the 21-cm line using a receiver on one of the Würzburg antennas, at Kootwijk.