On Wed, 27 Aug 2008 09:34:38 -0700, Jeff Liebermann
wrote:

I
can probably conjur my bad guess of a model of the Sinclair antenna,
but I'm playing vacation and would rather be doing something else.

No, I can't. Neither EZNEC or 4NEC2 will model dielectrics.

Also, this might be useful:
http://www.antennex.com/shack/Feb06/lpcad.html
LPCAD 3.0 will generate an NEC file that can be analyzed by your
favorite modeling program.

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