"Chuck" wrote in message
news:fVSdd.9064$6P5.7971@okepread02...
wrote in message
news:bMDdd.293802$3l3.275124@attbi_s03...
"Chuck" wrote in message
news:XrBdd.8254$6P5.7645@okepread02...
snip.
I'm not sure if I follow this correctly...
please elaborate further.
Certainly
To attain maximum gain per unit length the model dimensions
were all variables as was the number of elements. Not only
was the driven element current often less than another element in the
array
it was sometimes found that the maximum current element required a
diameter
of a few thousanths that was not sufficient to carry 1Kw.!
Obviously the gain attained was over ruled by the inability of the
element
to meet operational requirements.
I might add that I use fibre fishing rods for my antennas where I can
apply
the correct
wire diameters ( or aluminum foil) to an array without being encumbered
by
mechanical restrictions.
This removes me from the normal restrictions applied to antennas where
element diameter
is pre-controlled for mechanical reasons which often conflict with
scientific requirements
The above statement does conflicts with your assesment stated above
regarding critical coupling
but this is what I found and I will leave it at that
Regards
Art.
Hi Art,
Ok, I'm always open minded to learn
something new...
Wow,,,...... there are not many people around who could say that !.
Since 99.999% of things presented as new are incorrect most experts
have determined that the odds favor them if they label EVERYTHING
new as in error. If something comes along that is really new they always
have the comment ' I knew about that a long while ago" to fall back on.
I'd like to establish a few things, though.
First of all, what modeling program are
you using?
Beasely AOP
This is the professional version that has more than enough segments
and variable dimensions available to lesson the chances of human input
errors
plus to handle elements that were in close proximetry to each other,
together
with 'Sommerfield ground' handling capabilities.
Is your empirical data consistent with
the models?
Not measured, my thought were that NEC would always
be closer than field measurements generated by an amateur.
How are you ascertaining your empirical
data?
How are you determining the current
amplitudes: By model? Or empirically?
By model,
The program provides % of max current at every segment,
phase and all that good stuff
And what are the machinations that
demand ultra-thin wires to establish
the gain?
Go for 80 % gain and the rest (20% ) for swr
Added half a dozen elements
All dimensions variable except boom length and perfect ground height
Remove one element at a time until max gain point is obvious
Note all dimensions are kept variable at all times.
You can email me if you care to not
discuss these things in an open forum.
Not necessary, This is the very reason I posted in the first place !
The program shows that the normal 2 element is not the optimum
in that a polygon of vectors beats a triangle of vectors.
At the same time with added elements you get diminishing returns in std and
conventional forms.
The program showed that 1 to 1.5 dbi was available over the standard
2 element on the same length boom.if one could overcome mechanical
restraints.
(I was comparing to a Beasely example of what gain could be attained for two
elements on a 7 foot boom)
Now that is not the end of the experiment as I cannot verify the accuracy of
the program,
because I did not write it, and I certainly cannot say that my modelling
aproach is
without error since that is what many 'experts' point to if they don't like
the results.
It was for that reason I asked if any similar data had been made available
for boom length
by reputable programmers and antenna 'experts' for comparison purposes ., If
these initial
results were quoted as accurrate there would be howls from all the resident
antenna ' experts"
and I would immediately be placed in the six foot hole that they have been
trying to put
you in for the last eight years
Art
73, de Chuck, WA7RAI
wa7rai at cox dot net