On Fri, 12 Feb 2010 08:14:44 -0800, "Steve" wrote:

I'm thinking of building a 3 element 20 meter quad (full size)
and I'm stuck on the spreaders. Many people use bamboo
or aluminum with insulators at the tips. Can anyone suggest
alternatives....hopefully inexpensive, common materials?
TIA
Steve

PVC pipe? Probably too heavy and too easy.

Maybe vinyl tubing or thin wall pipe. For stiffness, fill the tubing
with expanding foam urethane fence post compount, cement, or epoxy.

Perhaps an inflatable antenna using rolled vinyl tubing for the
structural elements? Just get a sheet of thin vinyl tubing, or heat
seal packing material, some glue, a hot wire sealing contrivance, and
build the quad.
http://www.uline.com/BL_2107/4-Mil-Poly-Tubing
The connecting wires will provide the required dimensional stability
(assuming they don't stretch under tension). Obviously, this would
not be a permanent installation. Something like this with a different
arrangement of supports:
http://www.china-inflatable.com/products/sports/T11-364.htm

Incidentally, there's no reason that the quad has to be square shaped.
The quad can be circular. A large round cardboard cylinder, with the
wire elements wrapped around the outside should work. Be sure to add
a tail so that it doubles as a wind vane.

You can also build an inflatable tower to support your quad:
http://towers.ltaprojects.com/LTA_Towers/LTA_Tower_Home.html



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558