You can model this with EZNEC:

Get 2 Cushcraft 40M rotating dipoles and a boom to hold them. Tune the
dipoles separately to 7 MHz. Put them on the boom, observe operating
results, and adjust the driven element to your favorite 40M slot. The
elements interact, so the reflector may require adjustment as well, to keep
it around 7 MHZ when you adjust the driven element.
--
73, Dave, N3HE
Cincinnati OH

"Tom Ring" wrote in message
.. .
Tom Ring wrote:

I have a coworker that would like to put up a 40m antenna on his tower
that has some gain and directivity. I have modeled a few things, and