[TowerTalk] VERTICAL BALUN

[Ian White G/GM3SEK]

>> 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.
>
Tome makes some fair points...

>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.
>
Wouldn't try to "stop" anybody anyhow, and certainly don't want to get 
into a Holy War about it (oops, sorry Steve :-)

However, we do have to recognize that the same device has more than one 
application, which is why one name won't fit all its uses.

If you're connecting it to a symmetrical antenna (such as a dipole) in 
order to improve its voltage balance, then certainly I'd call it a 
balun.  But if the antenna isn't even supposed to have voltage balance 
(such as a vertical GP) then calling it a balun is IMO misleading.

>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
>use.
>
>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?
>
If we were starting afresh, "feedline choke" comes closer than any other 
one name... but Marketing will instantly point out that customers expect 
"BALUN" on the label, so that's what we get.


>> I agree completely with your definition of "balance" as
>requiring equal
>> voltages from each conductor to the environment around the
>conductor.
>> 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
>> antenna.
>
>Well, that isn't true.

Sorry, my last claim was not well expressed. What I meant was, if the 
antenna isn't intended to be balanced in the first place (that's 
*voltage* balanced, remember) why are we calling this thing a "balun"?

Not particularly disputing your other points either, Tom, but I've 
already slept on this one, and then spent the day working, so if I don't 
hit "Send" soon, it'll slip till Sunday. Let's cut to the key point 
which is in your final sentence:

> as people I'm
>communicating with know what it really is.
>
The people I'm communicating with often don't... and that makes all the 
difference.


-- 
73 from Ian G/GM3SEK         'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek