On Sat, 27 Aug 2005 14:31:06 -0700, dansawyeror
wrote:

Since you are talking about 50 Ohms I assume you are talking about a
transmission line. If that is the case you should definitely match the feedline
to antenna at the antenna feed point. Any attempt to match the feedline with a
tuner in the shack only turns the whole feedline into part of the antenna
system. By doing that you have lost any good work in building the antenna.

The feedline is -always- part of the antenna system. If it troubles
you to think about matching in the shack, just think of the
transmission line as part of a matching network located at the
feedpoint. In other words, the feedpoint network is comprised of 50'
of coax and coupla LCs in a box. This network then connects to the
transmitter through a non-resonant (flat) coax line.

I am not sure what you mean by -always-. If you mean there is no such thing as a
perfect coax line then your statement is true but does not add any real value.
If you mean by -always- the feedline is a significant component in the antenna
system then I would have to disagree. When operated at their design point coax
transmission lines do not radiate and are not part of the radiating "antenna
system".

Coax is designed to work in a specific environment as a transmission line. These
transmission lines are designed not to radiate. When transmission lines are
operated significantly outside their design range the radiate. Adding a tuner to
one end only controls the characteristics at that point. It does not 'clean up'
the mismatchs.

Dan



Wes Stewart wrote:
On Sat, 27 Aug 2005 14:31:06 -0700, dansawyeror
wrote:


Since you are talking about 50 Ohms I assume you are talking about a
transmission line. If that is the case you should definitely match the feedline
to antenna at the antenna feed point. Any attempt to match the feedline with a
tuner in the shack only turns the whole feedline into part of the antenna
system. By doing that you have lost any good work in building the antenna.


The feedline is -always- part of the antenna system. If it troubles
you to think about matching in the shack, just think of the
transmission line as part of a matching network located at the
feedpoint. In other words, the feedpoint network is comprised of 50'
of coax and coupla LCs in a box. This network then connects to the
transmitter through a non-resonant (flat) coax line.

On Sat, 27 Aug 2005 17:49:42 -0700, dansawyeror
wrote:

I am not sure what you mean by -always-. If you mean there is no such thing as a
perfect coax line then your statement is true but does not add any real value.
If you mean by -always- the feedline is a significant component in the antenna
system then I would have to disagree. When operated at their design point coax
transmission lines do not radiate and are not part of the radiating "antenna
system".

An antenna tuner or transmatch, if you prefer, doesn't radiate and is
part of an antenna system. the fact that a transmission line radiates
or not doesn't mean it isn't part of the system.

Danny, K6MHE

On Sat, 27 Aug 2005 17:49:42 -0700, dansawyeror
wrote:

I am not sure what you mean by -always-. If you mean there is no such thing as a
perfect coax line then your statement is true but does not add any real value.
If you mean by -always- the feedline is a significant component in the antenna
system then I would have to disagree. When operated at their design point coax
transmission lines do not radiate and are not part of the radiating "antenna
system".


Well, now, we've just morphed "antenna system" to "radiating antenna
system."

But never mind, nothing's changed, you're still all wet. Of course
the feedline is a component in the antenna system regardless of
whether it radiates or not. BTW the line can be perfectly matched and
radiate or it can be highly mismatched and not radiate.


Coax is designed to work in a specific environment as a transmission line. These
transmission lines are designed not to radiate. When transmission lines are
operated significantly outside their design range the(y) radiate.

Squeak squeak---squeak squeak---squeak squeak, there I just screwed a
tee connector on the end of a run of 50 ohm coax and on the tee I
screwed on two 50 ohm loads. The line is now terminated in 25 ohm
making the SWR 2:1. 'Splain to me how well this line, "operating
outside its design range", radiates.

If that's not "significantly" far enough outside the "design range"
then allow me to remove the loads, add two more tees and terminate
them with four 50 ohm loads, making the SWR 4:1. How well does the
line radiate now? Should I continue to 8:1 or are you convinced?


Adding a tuner to
one end only controls the characteristics at that point. It does not 'clean up'
the mismatchs.

It can certainly "clean up" the mismatch at the input to the tuner,
which unless I've been deluding myself for 45 years or so, is the
point.