Not likely. Such an array would be about twenty wavelengths wide (and still
have reasonable side lobes).
It is improbable that one could keep the required elements' current close
enough in phase to be able to realize a 2.5 degree beamwidth. Too
expensive. If used on a path that is longer than something like 10Mm, the
narrow beam will occasionally miss the target (unless one adds skewing,
which would be expensive in this case).
In other words, a SW broadcast system would not want such an antenna.
Less expensive and more reliable to buy a larger transmitter.

Why do you ask?

Mac N8TT

--
J. Mc Laughlin; Michigan U.S.A.
Home:
"Max Power" wrote in message
...
Has anyone ever designed a SW transmission system using curtain arrays
that
has a beamwidth of 2.5 to 5 degrees?
Most standard curtain arrays [HR 4/4/1 to 12/6/1] have 15 to 30 degrees of
beamwidth.