I found a used book on composites. It indicated that C-glass was the
preferred fiberglass for use in radomes. Googling around, it looks like
the Chinese have flooded the market with C-glass, so I guess that
statement isn't operational anymore.
I found out the AWACS aircraft uses S-2 glass in its radome. Now that
cloth is easily purchased at Tap Plastics (well if you are on the left
coast). The claim is the material is good to 10GHz.
They stock the Hexel version. S-2 glass is not very rigid, so you can
make just about any shape you want. Now for the AWACS, they used epoxy
resin. This might be a function of dielectric constant, which doesn't
seem to be listed for any of the resins carried at Tap. I've only used
the marine grade vinyl ester, since it is compatible with all the cloth
they sell. Possibly in manufacturing the radome for the AWACS, they
didn't want to vacuum bag it, so epoxy resin would get around that need.
For DIY construction (i.e. without vacuum bag gear), you just build the
composite so it cures between mylar sheets. The vinyl ester doesn't
really get hard in the presence of air. Given the cost of the resin, you
might as well get the full strength. You don't need a vacuum, but you do
need to restrict the air a bit, hence the mylar.
If anyone gets serious about radoming home brew antennas, I can write up
a bit more on the fabrication. PVC pipe certainly effects the antenna.