Clifford,

There are two styles of hexbeam: the older design which has a W-shape
Driver and a W-shape Reflector, and which I call the "classic" on my
web site; and my newer broadband design which has a W-shape Driver and
a U-shape Reflector.

I found in my lab notebook a 2m version of the broadband style; its
dimensions a half-Driver 21"; Reflector 40"; end gap 2.5". I think
I assumed wire construction using #14 bare copper. That would give a
hexagon radius of 12.5".

When I model this with EZNEC I see about 3.8dBd Forward Gain and 19dB
F/B with VSWR=1.4. The problem is that the rearward response is very
smooth and "well behaved" so probably not much use for DF.

If I increase the end gap to 5" the Forward Gain and F/B remain about
the same, but the azimuth pattern devlops deep side nulls (38dB) at
plus and minus 130 degrees which may be useful. The VSWR deteriorates
to 1.8:1.

Hopefully that may give you a starting point for experimentation. If I
get a chance I'll try some modelling experiments on the classic design
also.

73,
Steve G3TXQ