In article ,
John Smith wrote:

Telamon wrote:
...
Well, I think you mean noise currents. The signals the single element
antenna picks up are also common mode.

Here the voltage type UNUN has the advantage of DC isolation between the
...

Balun = "BALanced-to-UNbalanced"

Unun = "UNbalanced-to-UNbalanced"

What type of antenna you are feed AND what type of feed your
rcvr/xmitter expects SOLELY determines if you should use a balun or a
unun ...


That's the conventional terminology. I capitalize to make the acronym
obvious.

Five reasons I can think of to use some type of transformer.

1. Impedance transformation.

2. Matching a balanced or unbalanced antenna to the same for the feed
line used.

3. DC static electricity isolation.

4. Isolate RF ground from AC mains ground.

5. Decouple the antenna feed from the antenna so the feed does not act
as part of the antenna.

--
Telamon
Ventura, California