Cecil Moore wrote:

Or maybe not. EZNEC apparently won't properly model
the Lattin antenna. www.g3ycc.karoo.net/lattin.htm
. . .

I took a look at it, and sure enough, it can't. The antenna is
constructed from tubular 300 ohm twinlead, and EZNEC has no way to
account for the dielectric between conductors. In that antenna, it looks
like the velocity factor of the differential mode field between
conductors would be important to its operation, and without the ability
to model the dielectric between conductors, EZNEC wouldn't get the
velocity factor right.

When I see a claim that EZNEC can't model a particular antenna, I often
find that the reason for the claim is that the antenna's inventor or
seller has dreamed up some magical property to explain the impossibly
good performance he's claiming for the antenna. EZNEC models the antenna
just fine, it just doesn't model the magical property and validate the
claims -- that is, it shows how the antenna really works, not how the
huckster claims it works. But there are, certainly, some kinds of
antennas which it really can't model properly for one reason or another.
The Lattin antenna is one of those.

Roy Lewallen, W7EL