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-   -   Even more on antenna feedlines and matching to an antenna. (https://www.radiobanter.com/shortwave/83673-re-even-more-antenna-feedlines-matching-antenna.html)

RHF December 5th 05 09:04 AM

Even more on antenna feedlines and matching to an antenna.
 
Frank - " The wire is suspended about 6 inches above
my west concrete wall which is about 5 feet high. "

Frank - Clarification Please :
Is this the Wire Antenna Element ?
or the Coax Cable Feed-in-Line ?

If this is the Windom Wire Antenna Element ?
then the Antenna itself is only about 5' 6"
above Ground Level.

Question does the Concrete Wall have Re-Bar
(Iron-Metal inside) running through-out it ?
{ A Unified Ground Radial }

i want to know ~ RHF

[email protected] December 5th 05 04:26 PM

On-the-Fence a {Low Level} Windom Antenna [Was : Even more on antenna feedlines and matching to an antenna.]
 
I've always wondered how this antenna would have performed if the
feedpoint had been in the center as a classic dipole and the xfmr
Z-ratio was different than 1:1. Would this allow some semblance of a
"multiband" antenna as opposed to the direct feed or 1:1 situation
where the antenna essentially is optimum on the primary freq and the
3rd harmonic? Why did I choose the Windom? Because the radio room is
directly across from the 35% length point on the antenna. Even though
it works well I'm not convinced that there is anything "magic" or
unique about the 33 to 35% point on a wire antenna unless there is a
true overall impedance averaging effect when fed at this point. (???)

Frank


RHF December 5th 05 04:44 PM

On-the-Fence a {Low Level} Windom Antenna [Was : Even more on antenna feedlines and matching to an antenna.]
 
So Frank what you are saying is that you built an
Available Space Antenna that Fit the Conditions you
had considering the Lay-Out of your Home and Property.

Hey sometimes we get Lucky and in the end
.. . . what works - Works ! :o)

enjoy your radios and antennas - iane ~ RHF

[email protected] December 5th 05 04:53 PM

On-the-Fence a {Low Level} Windom Antenna [Was : Even more on antenna feedlines and matching to an antenna.]
 

wrote:
I've always wondered how this antenna would have performed if the
feedpoint had been in the center as a classic dipole and the xfmr
Z-ratio was different than 1:1. Would this allow some semblance of a
"multiband" antenna as opposed to the direct feed or 1:1 situation
where the antenna essentially is optimum on the primary freq and the
3rd harmonic? Why did I choose the Windom? Because the radio room is
directly across from the 35% length point on the antenna. Even though
it works well I'm not convinced that there is anything "magic" or
unique about the 33 to 35% point on a wire antenna unless there is a
true overall impedance averaging effect when fed at this point. (???)

Frank

----------------------------------
About 10 years ago I experimented 9again) with dipoles for HF.
I tried several different ratios in an attempt to improve recpetion.

I tried a dipole cut for 10MHz and then one cut for 18MHz.
I tried 1:1, 2:1, 3:1, and 9:1.

A 70' "long" wire out performed the dipoles on every frequency, with
every
ratio even on the design frequency with a 1:1.

Of the dipoles, the 2:1 transformer with the 5MHz dipole worked best.
I suspect it worked best because of it's greater length.

The transformers seemed to mainly decouple the coax from the antenna.
If I ever get the time I would like to retry these experiments with
triax or
twinax.

I tried a direct connection with several ferritte cores, but after
reading John
Brynt's excellant article on "Is your Feedline acting like an antenna"
I accept
that I did not have anywehre near enough inductance to supress common
mode effects. I had a LOT of RFI from household devices.

Terry


Telamon December 5th 05 06:30 PM

Even more on antenna feedlines and matching to an antenna.
 
In article .com,
wrote:

Snip

The other issue is where my "ground" really is here in dry, dusty AZ.
I have dug down over 4 feet in some parts of the yard and there is no
moisture there either! So trying to define a ground is useless also.


Snip

You can always put radials on / in the ground from the antenna ground
point for a counter poise when you have poor ground conductivity.

In your case part of the antenna is a counter poise so you don't need it
but you could give running one under the length of your "Windom" to see
if it makes things better or worse.

--
Telamon
Ventura, California


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