[TowerTalk] VERTICAL BALUN
w8ji at contesting.com
Fri Nov 4 16:20:03 EST 2005
> Sorry, Tom, I have a big problem about using the term
"balun" around any
> antenna that cannot ever be "balanced" as you define it -
and isn't even
> intended to be.
That's fine. I agree it isn't a perfect name. It's a lot
like Double Zepp.
But if we don't call it a balun, we probably should stop
everyone from calling the device that attempts to force
equal currents on both symmetrical looking output terminals
and has a coaxial input a current balun.
Not that we have done that, what should we call that device?
Un Un doesn't fit, because an un-un doesn't imply or often
even have common mode isolation. Besides, the antenna also
isn't perfectly UNbalanced. It's in a grey area between the
land of balanced and unbalanced, just like many antennas we
Should we rename the very same device for each application?
80% balun? "Current Nearly Balun", or maybe "Current almost
not a balun"? Send out stickers and some meters so users,
depending on the load, can rename the universal device?
> I agree completely with your definition of "balance" as
> voltages from each conductor to the environment around the
> But that definition categorically excludes any vertical
antenna close to
> ground. Such antennas cannot ever be balanced
voltage-wise, and they
> aren't intended to be. There's nothing a "balun" can do
for such an
Well, that isn't true. It can do a great deal for the
system. A current balun by definition allows each terminal
to float to any voltage it requires to force balanced
currents into the load. Since the load is a radial system
and a vertical element, that's exactly what we need to keep
the feedline from radiating.
Worse yet, if we assume that is true then most dipoles
people use also can't use baluns. That's because most
installations don't have the feeder exiting in a perfectly
balanced area where the influence of electric fields from
each antenna half are equal and opposite, and the magnetic
field is canceled at that point. Don't we create a larger
problem if we no longer use the name "current balun" when
the load is not perfectly balanced?
> I'd say the correct term is a "feedline choke" or
> The device is exactly the same, of course. The difference
is, now we're
> saying what we really want it to do.
OK. I agree. Now we have to stop everyone from using the
term "current balun" for that device, even though it is
exactly the same device. Unless we include multiple labels
so they can change current balun to feedline choke when the
load isn't perfectly balanced. If some buys a 4:1 current
balun and uses it with their Windom, for example, they would
just stick on a new label calling it a "4:1 common mode
> As I said earlier today, we hams have a remarkable talent
> ourselves by deliberately calling things something
different from what
> they are. Please let's stop - the universe is already
I think the point we miss is name words are only used to
convey what something is. I could easily be accepted as
Charles, for example, and if you always had known me only as
Charles W8JI you would know me as Charles.
I have no problem with people calling matching networks
antenna tuners. They aren't antenna tuners unless they are
mounted right at the antenna, but we all know what the name
means. I have no problem with the name Double Zepp or
Extended Double Zepp to describe a doublet, as people I'm
communicating with know what it really is.
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