Without getting into the whys of our fascination with SWR, the StepIR
answers the concern of all those who cannot stand their SWR to be
anything other than 1:1, all other concerns notwithstanding.
Or those who need their antenna to work across an entire octave of HF
without the element/trap complexity of other solutions.
Or those who might want to pull in the element length for reasons of
appearance, wind drag, etc, when not operating.
Given that people have tolerated decidedly inferior designs from
M****** all these years and defended them to the end, I can't see that
the StepIR particularly deserves any duns, other than the moving parts
are a complexity that will sooner or later must place it in the
category of the KT34XA, a favorite, and a performer, that has
mechanical issues that must be dealt with in the long term.
As to how long and exactly what issues, the StepIR needs the time in
grade to see how it does in various environments. Each owner will have
their own tolerances to whatever develops, and what it takes to keep
it in repair.
I think that Tom's issues are overstated for the purposes of clarity,
but in force for theoretical discussions.
Anyone with YO can run a 3 element problem with the fixed spacings and
boom length of the StepIR and see that there is a continuous solution
from 20 to 10, whose accomodation to boom length is no ghastly
The front-to-back penalty experienced on the StepIR at 10m is less
than the f/b penalty routinely ignored when stacking two yagis
designed to be used one at a time in the clear.
Again, the mechanics will be the achille's heel, if any.