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Old November 18th 06, 02:40 AM posted to rec.radio.amateur.antenna
Gene Fuller Gene Fuller is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 342
Default 4:1 Current Balun Common Mode Impedance?

Roy Lewallen wrote:
Gene Fuller wrote:

Yes, I have a copy of your article, and I have actually read it. I
think I even understand it. I took a fresh look just before I made my
first post in this thread. The schematic for Sevick's Guanella 4:1
balun is exactly the same as your figure A3-4.


Then I'm puzzled by your statement that if an antenna is completely
symmetrical, no balun is necessary. The very first two figures in the
article and accompanying text show this isn't true. Of course, if you
have a symmetrical antenna AND the feedline is placed symmetrically AND
you have a truly balanced tuner, then there will be no common mode
current and a balun won't do anything. Maybe that's what you meant.


Roy,

If I said that no balun is necessary then I apologize. I certainly did
not intend to say or imply such a thing. I do believe, however that a
single core balun would serve well if the antenna is balanced by design
and by its environment.

The question is how the single core balun performance degrades as the
antenna becomes less balanced through, for example, an asymmetrically
placed feedline. It seems difficult to analyze that problem, and
experimentation would be required.

73,
Gene
W4SZ