Tom Holden wrote:

I think you mean the 3-5 degree HF array could only have been scale modelled
at much higher frequencies.

The largest dish antenna is the Arecibo radio telescope at 305 meter (1000')
diameter http://www.naic.edu/public/the_telescope.htm. That could give a 5
degree or better beamwidth above 13-15 MHz if it had a suitable antenna at
the focal point. I don't know what its lowest frequency of operation might
be but this page http://www.naic.edu/techinfo/prcz/prczinfo.htm indicates
that 13.36 - 13.41 MHz is protected for radio astronomy. It's possible that
its original use for radar back scatter studies of the Ionosphere under the
DoD may have had it transmitting near the 20 meter band! With 5 degree
beamwidth pointing straight up, it would take a lot of hops to make any
decent terrestrial DX!

Tom

Has anyone here ever seen a real curtain antenna while standing
underneath? I visited the old VOA plant in Mason, Ohio "Bethany" in the
late '60s and got the full tour with my high school's ham radio club.
Today its just another golf course for Cincinnati.

--
Former professional electron wrangler.

Michael A. Terrell
Central Florida