Yes but I believe that the early computorisationd he used was based first on
mechenical designed elements which were then imputted.He did not mess with
the element diameters after that.As an aside if you densly populated a boom
with elements many are put off by the low impedance being totaslly unaware
that an additional reflector an up the input impedance back again......
another example of what coupling can do for antennas
Art
"Yuri Blanarovich" wrote in message
...
Another was from the
Central States VHF Society and gives results of their 2004 gain
comparisons of many different antennas. Gain of these versus boom length
looks very ragged.

Best regards, Richard Harrison, KB5WZI



Gain vs. boom length makes sense only when comparing or tracking the same
antenna design i.e. Yagi with multiple elements. One can design lousy
antenna
on a long boom.

Jim Lawson, W2PV was one who after some modeling showed that gain in the
properly designed antenna is roughly proportional to the boom length
rather
than to number of elements. Some manufacturers "beefed up" their antennas
by
sticking more elements on the same boom claiming better performance.

Yuri, K3BU.us

wrote:

My ARRL books go back a decade or more
and the graph showing gain per boom length
has several curves based on different measurements
e.t.c. Has a graph been made based solely on NEC
program findings over say a perfect ground and at a uniform height?
Art



For VHF/UHF yagis in free space -

WA2PHW Gain Figure of Merit

G = 10 log (5.4075 B + 4.25) for B GT 1

Where G is gain in dBd and B is boomlength in wavelengths.

This is from a database of over 100 VHF/UHF yagis compiled in the early
90's. These are all real buildable yagis, and the antenna range numbers
closely agree with the computer models. The numbers were heavily
influenced by the 10 to 40 element K1FO series. Thanks again Steve.

Note that this predicts a zero length yagi should have about 6 dBd gain.
Any ideas on why it intercepts there?

tom
K0TAR

Tom, where is the link that goes with this info? It doesn't mean anything as
it stands
Art


wrote in message
. ..
wrote:

My ARRL books go back a decade or more
and the graph showing gain per boom length
has several curves based on different measurements
e.t.c. Has a graph been made based solely on NEC
program findings over say a perfect ground and at a uniform height?
Art



For VHF/UHF yagis in free space -

WA2PHW Gain Figure of Merit

G = 10 log (5.4075 B + 4.25) for B GT 1

Where G is gain in dBd and B is boomlength in wavelengths.

This is from a database of over 100 VHF/UHF yagis compiled in the early
90's. These are all real buildable yagis, and the antenna range numbers
closely agree with the computer models. The numbers were heavily
influenced by the 10 to 40 element K1FO series. Thanks again Steve.

Note that this predicts a zero length yagi should have about 6 dBd gain.
Any ideas on why it intercepts there?

tom
K0TAR

wrote:

Tom, where is the link that goes with this info? It doesn't mean anything as
it stands
Art


What? Of course it means something. It's an equation along with the
constraints.

Run any current decent 1 wavelength, or longer, yagi in your favorite
modeling program, and it will tell you whether you are near the gain you
should get for a well behaved yagi. Or it might tell you the model
isn't very accurate. It works well to test known designs against
unknown quality programs without having the known good modeling program
or test range.

If you want the database it was derived from, that might be arranged,
but it is in from a database program that Microsoft Office won't read,
so you might be out of luck there.

tom
K0TAR

Tom, let me be direct without being disrespectful What I modelled was a boom
length of 7ft for 20 metres and it is an abnormal yagi design which does not
fit what you are offering. I do not believe that NEC programs vary too much
on standard forms but when using tightly clustered elements on a short boom
lots of other things come in to play, and one has to be sure that the
program is all encompassing as designed to handle ALL abnormalities.
Obviously what you have offerred has serious problems on short yagi's let
alone abnormal design yagi's. It is my belief that because an element
reradiates
a portion of the RF that it received, extra elements that are closely
clustered can provide increased gain. Yes. my model
confirmed that but I was hoping that experts could point to a mathematical
analysis of max gain per unit length that was exacting in gain provided and
not "close enough" and not marred by other things that can occur by
measuring in the field.
It would appear from the responses that efforts in this area has not been
undertaken and which I will have to live with that.
But I do thank you for your offering
Art

"Tom Ring" wrote in message
. ..
wrote:

Tom, where is the link that goes with this info? It doesn't mean
anything as
it stands
Art


What? Of course it means something. It's an equation along with the
constraints.

Run any current decent 1 wavelength, or longer, yagi in your favorite
modeling program, and it will tell you whether you are near the gain you
should get for a well behaved yagi. Or it might tell you the model
isn't very accurate. It works well to test known designs against
unknown quality programs without having the known good modeling program
or test range.

If you want the database it was derived from, that might be arranged,
but it is in from a database program that Microsoft Office won't read,
so you might be out of luck there.

tom
K0TAR

wrote:

It would appear from the responses that efforts in this area has not been
undertaken and which I will have to live with that.
But I do thank you for your offering
Art

Sorry, based upon the variability of responses in the group, I thought
this was well within the limits. It was considerably closer to being on
subject than some that have gone from legitimate questions to raving
political nonsense with no one complaining. I won't make this mistake
again.

tom
K0TAR

No appreciable difference between them and NEC program results. You can
build every bit as good of an antenna using the curves and given formula as
you can a NEC program. Optimization of antenna built from either data still
requires the same cut and try tweaking to get the last .001 db out. For all
practical purposes the ARRL curves are as good as any. Obviously you have
some impractical uses in mind.


" wrote in message
news:gDfdd.278515$D%.137716@attbi_s51...

"Jimmie" wrote in message
. com...
A graph from NEC data is going to be pretty much like a graph from the
ARRL
books.

Come on Jimmy,' pretty much like' doesn't cut it on this newsgroup or in
any
of the professions
The same as pretty close is not accepted when doing math at college.
The curves in the ARRL book were done on 'standard' yagis
measured in the field, at least two of the curves therefore have measuring
errors, and possibly
three of those do not match NEC formulated curves.
Since you do not want to reinvent the wheel which curve or formula do YOU
want all to
follow for short boom antennas i.e. which curve, and there are many,
represents the "wheel" .
that can be specifically used as the datum curve in response to my
specific
request?

Note, a NEC produced gragh will produce a scattering of points for
different yagi's
but only ONE point for MAX GAIN PER UNIT LENGTH OF BOOM regardless of how
many elements are used which when used on short booms produce coupling
effects which
change current flow, an effect not generally seen when elements are not
critically coupled
as in the standard yagi..

Thus the reason I was specific in my request which should have
removed comments such as 'Patents" from those who seek arguments .

Art


By putting the data in a graphic form your are placing the same
limits on the data as they had to in the ARRL books. The ARRL graphs
give
you a pretty good idea of what goes on when you change element spacing,
number of elements and so on. What they dont do is alllow you to perform
optimization like the NEC programs . Graphing a NEC program output would
be
the same as going back to the time all you had was the graphs to go by
unless you are willing to do all the calculations on your slide rule or
calculator. What I am saying is that you already have this data. No
point
in
reinventing the wheel.Unless you think yiou can get a patent on it



Geez Jimmy you are just not reading posts of others ! If you have the
requested
data then point to a link, if I had the data already I wouldn't ask for
help
seeking it,.
Art



" wrote in
message
news:65Zcd.150611$He1.116446@attbi_s01...
Jimmy,
I did not want to choose a curve that matches my modelling which you
can
when presented with three different curves all of which are
formulated
at
different
times by different people. I would have thought that the advent of
NEC
would
render these curves redundant !
Art

"Jimmie" wrote in message
. com...

" wrote in
message
news:xOzcd.263953$D%.243703@attbi_s51...
My ARRL books go back a decade or more
and the graph showing gain per boom length
has several curves based on different measurements
e.t.c. Has a graph been made based solely on NEC
program findings over say a perfect ground and at a uniform
height?
Art


They probably have been done but there will not be much difference
between
them and the ARRL graphs. Its been long known how to calculate
antenna
gain,
computers just take the teadous labor out of it.

" wrote in message
news:wAYdd.406148$mD.70164@attbi_s02...
Tom, where is the link that goes with this info? It doesn't mean anything
as
it stands
Art


wrote in message
. ..
wrote:

My ARRL books go back a decade or more
and the graph showing gain per boom length
has several curves based on different measurements
e.t.c. Has a graph been made based solely on NEC
program findings over say a perfect ground and at a uniform height?
Art



For VHF/UHF yagis in free space -

WA2PHW Gain Figure of Merit

G = 10 log (5.4075 B + 4.25) for B GT 1

Where G is gain in dBd and B is boomlength in wavelengths.

This is from a database of over 100 VHF/UHF yagis compiled in the early
90's. These are all real buildable yagis, and the antenna range numbers
closely agree with the computer models. The numbers were heavily
influenced by the 10 to 40 element K1FO series. Thanks again Steve.

Note that this predicts a zero length yagi should have about 6 dBd gain.
Any ideas on why it intercepts there?

tom
K0TAR

wrote in message
news:tEUdd.167111$He1.55962@attbi_s01...

"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.
...

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.


Hi Art,

Anyone who believes they know it all,
has much to learn :-)

...

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

I get the impression that what you are doing
is placing any number of elements on a .1
lambda boomlength, in order to determine if the
close proximity EM interactions produce more
gain than just the standard 2 elements would
on that same boomlength.

In the optimization process, some of the
resulting element diameters are quite small.

You're asking if anyone else has looked into
this, and if any results have been published.

Is this a correct assessment so far?

73 de Chuck, WA7RAI

YES
Art
"Chuck" wrote in message
news:N3ded.9115$6P5.8189@okepread02...

wrote in message
news:tEUdd.167111$He1.55962@attbi_s01...

"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.
...

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.


Hi Art,

Anyone who believes they know it all,
has much to learn :-)

...

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

I get the impression that what you are doing
is placing any number of elements on a .1
lambda boomlength, in order to determine if the
close proximity EM interactions produce more
gain than just the standard 2 elements would
on that same boomlength.

In the optimization process, some of the
resulting element diameters are quite small.

You're asking if anyone else has looked into
this, and if any results have been published.

Is this a correct assessment so far?

73 de Chuck, WA7RAI