Ward Silver, N0AX, said:
"Also, it would greatly facilitate the discussion were we to be able to
include drawings - I noticed several misunderstandings that would not have
occured if the text was accompanied by graphics. I can tell that many
writing hours have been consumed trying to write clearly in a pure text
73, Ward N0AX
That is a good point Ward.
The graph that Steve, G3TXQ, made available really was interesting to study.
One could look at it and see the effect of going from a feed line coax
length of 1?4 wavelength to 1?2 wavelength to 3/4 wavelength. Adding the
common mode reactances to the CM choke reactance provided the red line
showing the net impedance of the CM path.
I might suggest that he add a note about the CM Choke impedance he used
since that was incorporated into the net impedance (Zcm) he was showing. The
Rcm at 0.5 wavelengths looks like it is zero, but that is because the scale
of the graph is ?4000 to +8000 ohms and resistances of say, 100 ohms, will
look like zero.
If someone does want to post a graph or a set of equations and they do not
have a web site or are uncomfortable with the mechanics of doing something
like that I would be happy to assist them. We can post such items at a new
location (I even have the folder set up now)
people could look at them or download them for future reference. They can
Just send me what they want to post as a reference in their email and I will
save it on that site for them.
73, Tod, K0TO
On 4/21/12 9:12 AM, "Ward Silver" <firstname.lastname@example.org> wrote:
> I'm really enjoying the multiple threads and discussions that started with
> baluns and have come around to an analysis of the entire antenna system.
> That changing just one element of the entire system in isolation is
> unrealistic is a key point that most hams do not appreciate - indeed, they
> rarely hear that point of view. They learn about antennas as one independent
> thing, feed lines are another thing, baluns a third thing, and so forth.
> Thus, they tend to analyze and troubleshoot and modify assuming changes "here"
> don't affect behavior "there". Since changing almost any part of the system
> affects the entire system, the results are wildly inconsistent and often
> mystifying - as noted by Ian and others. At any rate, the discussions have
> provided numerous examples to use in explaining antenna system behavior to our
> clubs and fellow hams (and in my case, readers) - thanks.
> Also, it would greatly facilitate the discussion were we to be able to include
> drawings - I noticed several misunderstandings that would not have occured if
> the text was accompanied by graphics. I can tell that many writing hours have
> been consumed trying to write clearly in a pure text environment!
> 73, Ward N0AX
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