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.