No. I expected someone who is an engineer and commands the language
better than I to explain that they are not the same and how they fit
together thereby adding a little enlightenment to this thread.
73,
Barry
K3NDM
On 10/2/2013 1:07 PM, David Gilbert wrote:
What do you expect Krause will tell you? That feedpoint impedance and
radiation resistance are the same thing?? I guarantee that it will not.
Did you not understand that feedpoint transformations transform the
combination of all impedances present at that point, and therefore
leave the relative magnitude of the various components (and therefore
the efficiency of the system) the same?? Or are you somehow of the
opinion that a folded element is not a feedpoint transformation??
I'm really having trouble understanding your logic here.
Dave AB7E
On 10/2/2013 9:26 AM, Barry LaZar wrote:
Everybody,
I see a real problem here. Please someone open up the authority,
Krause, and see what he says. His work is the basis of a whole lot of
what we have today.
73,
Barry
K3NDM
On 10/1/2013 10:55 PM, Bob Cunnings wrote:
Here's a link to the W8JI radiation resistance topic:
http://www.w8ji.com/radiation_resistance.htm
where the antenna efficiency issue is analyzed - using a 1/4 long
folded radiator as the example. In this analysis the antenna efficiency
is unchanged because total power and ground loss power terms remain
constant.
Bob NW8L
On Tue, 1 Oct 2013 14:48:55 -0700
"Ron D'Eau Claire" <[email protected]> wrote:
The important value is the resistance at the feed point of the
radiator, independent of any matching devices used.
Adding a 4:1 or other transformer is simply adjusting the impedance
the feed line sees, like any other matching network you might use. It
has no effect on the feed point resistance of the antenna.
A 1/4 wave long folded radiator has a feed point resistance of 4x the
typical 1/4 wavelength radiator, quite independent of the ground
system. Hence the efficiency is higher.
73, Ron AC7AC
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