Has anyone tried this antenna or simulated it in EZNEC?
Clearly someone has modeled it in EZNEC, as, according to the article, that is
how the antenna was developed originally, and the source of the plots provided.
My only comment on that is that it would be interesting to compare the plots
provided with those over "high accuracy" ground rather than MININEC ground,
as the Summerfield-Norton algorithm does a better job of modeling the losses.
I'd also be interested in the wire losses and the feedpoint impedance, particularly
on 80m, where the feedline may radiate more than the antenna in practice.
Basically on 40m it is a half wave dipole with the ends bent around nearly back
to the feedpoint, giving a total length of 1/4 wavelength. This lowers the
radiation resistance quite a bit. By contrast, the CrankIR vertical uses a wide
top section so the far end doesn't drop quite as close to the feedpoint, which
improves efficiency somewhat.
I've modeled several similar designs as part of a project on shortened 160m
antennas, and, in spite of the low radiation resistance, they can be made to
work reasonably well. I also modeled the "C" vertical. In both cases the
current distribution on other bands certainly isn't optimum, but can be at
least usable. (The C antenna also advertises itself as capable of multi-band
operation with a tuner, though it really works best as a single-band antenna.)
I wouldn't count on operation below 40m with this design, however. Yes, it may
radiate somewhat: I've made 80m contacts using the cord to my soldering gun
laying on my workbench, but I wouldn't consider that an effective antenna, either.
So if you want a good 40m antenna, I'd stay with the antenna is presently
dimensioned, where it uses about 1/2 wavelength of wire.