> The conclusions in a nutshell are:
> 1) It's an electrically short dipole which is centre-loaded by two
> inductive coax stubs
> 2) Made from RG58 the stubs add considerable series resistance, leading
> to unacceptable losses
> 3) The stubs' series resistance, added to the short dipole's low Rrad,
> tends to produce acceptable SWR figures which may well fool the unwary
> into thinking the antenna is behaving well!
> 4) Performance bandwidth is much reduced, although not as much as if the
> stubs were lossless :)
> 5) In a multi-element array, other factors such as
> driver/reflector/director spacings will preclude the antenna size
> shrinking uniformly by the Velocity Factor.
> Apologies if this is all "old hat". The results were of interest to me
> and seem to confirm Terry's (N6RY) comments in a very old thread:
I agree 100% on all counts, and even if this is "old hat" it bears
repeating every once and a while. I did the same kind of modeling
exercise (no measurements) when someone on eHam was asking if this
sort of antenna was any good. There's even a further trouble with
N0KHQ's Moxon in that the reflector shield isn't even split, so the
reflector doesn't even have stubs in series !
I'm glad you have the site up, it will be a good reference for warning
people away from this construction ;-)
It's probably one of the more damaging antenna myths out there, tnx
for taking the time to write it up!
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