On Thu, 28 Apr 2005 18:03:40 +0000 (UTC), our tipsy English cousin,
"Reg Edwards" wrote:

Balanced to Unbalanced WHAT ?

"Balun" is a contraction of "Balanced to Unbalanced "TRANSFORMER".

No, I stand by my definition: BALUN is a contraction of BALanced to
UNbalanced.

If you want to call it an impedance transformer, then call it a "BALUN
impedance transformer." The functions are independent. In fact, many
"broadband transformers" separate the functions into "balun" and
"transformer."

For example in Fig 2 of this reference:

http://www.minicircuits.com/appnote/howxfmerwork.pdf


What is the transformation ratio of the W2DU "balun" and other devices
which serve a similar purpose?

Let the complex line constant of the line comprising the balun be x =
alpha +j Beta .

Then with Zl being the load, the input Zin will be found from:

Zin = Zo * ((Zl + Zo *tanh(x))/(Zo + Zl *tanh(x))

Which of course for a lossless line of Zo and a load of Zl = Zo
reduces to Zin = Zl = 1:1

But you know all of this.

Between which pair of impedances does it match?

It isn't designed to "match" anything. It's designed to suppress
common-mode current. Other than that, it's a length of transmission
line that behaves just like any other transmission line of the same
length, loss and impedance. But you know this too.


If YOU cannot provide answers then there are many old-wives who can.

There is a program named BALCHOKE available free from my website.

I have no wish to participate in futile arguments about the meaning of
words. They can drive one to drink

I believe you have arrived.