As I just posted in another followup, MultiNEC (add-on for EZNec and
other NEC programs) takes care of just this sort of thing for you, and
takes much of the tedium out of the process. As an Excel spreadsheet,
it does require that you have Excel on the computer you're using.

Cheers,
Tom

Reg Edwards wrote:
"JC" wrote
Thanks for help, I think I wrongly explained my problem, here is the
question:
1/ I design an antenna, for instance a 3 el 20m beam.
2/ I enter into EZNEC wires dimensions, spacing, height, source.....
3/ EZNEC calculates gain, F/B, SWR....and results are acceptable.
4/ Now let's suppose my objectives are max F/B as I have a QRM
source
opposed to my favourite transmitting direction and SWR 1.5 on a
given
frequency range as my transceiver is very SWR sensitive and I can't
use an
antenna tuner.
I accept changing wire lengths and spacing but not boom length.
Is there a way to have EZNEC, or another software, doing automatic
iterations until it reaches the best F/B-SWR compromise ?

----------------------------------------------------------------------
--------------

Let us see what would be involved if you had EZNEC and had to do
everything else yourself the hard way. You already have a crude,
satisfactory design for 3 elements, wire lengths, wire diameters,
spacing, height, etc.

Only the boom length and presumably wire diameters and height are
fixed and you wish to optimise everything else for maximum F/B ratio
and minimum SWR.

Everything else comprises : 3 lengths and 1 spacing. This makes a
total of 4 independent variables.

You now vary the first variable over a range of say 4 increments,
keeping all the other variables constant and keeping a record of the 4
results of F/B ratio and SWR

You then vary the second variable over a range of 4 increments,
keeping all the other variables constant and keeping a record of the
results.

You continue to do this until you have done all possible combinations
of the 4 variables. You will have a 4-dimension array of results of
F/B ratio and SWR, making a total of 512 observations.

Now search the observations until you can find the maximum of F/B
ratio combined with minimum of SWR

If it looks as though the minimum SWR or the maximum F/B ratio lies
outside the 4-dimensional array then shift the variables in an
appropriate direction and repeat the whole procedure until a max and
min are found.

The trouble with modelling programs is you have to enter element
lengths and spacing via the keyboard. It would be nice to have a
program to do it for you. I am unfamiliar with the situation. Such a
program might exist - one which outputs F/B ratio and SWR.
----
Reg.

As mentioned in another posting, YO (Yagi Optimizer) would be a good
bet. Strange that piracy caused the author to quit offering it
completely; seems like any sales are better than none, and not selling
a program only makes piracy more likely, not less.

But check out the EZNEC co-pilot program from Dan Maguire, AC6LA, at
http://www.ac6la.com/. That page lists several of his offerings; it's
MultiNEC that you'll be most interested in. Though it may not
completely automate the optimization, it should make the process much
easier and faster for you.

Cheers,
Tom


JC wrote:
Thanks for help, I think I wrongly explained my problem, here is the
question:
1/ I design an antenna, for instance a 3 el 20m beam.
2/ I enter into EZNEC wires dimensions, spacing, height, source.....
3/ EZNEC calculates gain, F/B, SWR....and results are acceptable.
4/ Now let's suppose my objectives are max F/B as I have a QRM source
opposed to my favourite transmitting direction and SWR 1.5 on a given
frequency range as my transceiver is very SWR sensitive and I can't use an
antenna tuner.
I accept changing wire lengths and spacing but not boom length.
Is there a way to have EZNEC, or another software, doing automatic
iterations until it reaches the best F/B-SWR compromise ?

JC - F8ND


"Reg Edwards" a écrit dans le message de
news: ...

"JC" wrote in message
...
Is there a software which can design an antenna (like EZNEC or
similar )
then allows to automatically optimize its dimensions according to
given
requirements: max gain, F/B, min swr... and accepted dimensional
parameters
changes: boom length, spacing....
JC
----------------------------------------------------------------------
-------
Dear JC,

You don't need software. What you describe is non-existent anyway.
What you want is a long experienced antenna designer who can be
permanently engaged on your behalf. There are very few of such
creatures about.

You will have to be numerically quite specific about particular
problems. And even then you will get solutions which, with luck, are
probably only in the right ball-park.

On the other hand, ball-park solutions are perfectly satisfactory. In
the nature of events, no-one has ever solved an antenna problem which
is other than in a ball-park. Fortunately, antennas work quite well
even when in the wrong ball-park.

Download a free copy of EZNEC and in a few months time you may have
solved your first complicated, specific problem. As time goes on, you
will become more adept and there will be no need to engage a long
experienced antenna designer. You will have become one youself and
can offer your services for hire.

If you have a specific problem you may, if you are lucky, find a
computer program written by someone who has already solved it. But its
highly unlikely to be exactly the same problem. It will be in a
somewhat different ball-park.

Optimisation is out! You will have to contend with whatever you can
get your hands on. What's been done before. Take it or leave it!
----
Reg.

In message , JC
writes
Thanks for help, I think I wrongly explained my problem, here is the
question:
1/ I design an antenna, for instance a 3 el 20m beam.
2/ I enter into EZNEC wires dimensions, spacing, height, source.....
3/ EZNEC calculates gain, F/B, SWR....and results are acceptable.
4/ Now let's suppose my objectives are max F/B as I have a QRM source
opposed to my favourite transmitting direction and SWR 1.5 on a given
frequency range as my transceiver is very SWR sensitive and I can't use an
antenna tuner.
I accept changing wire lengths and spacing but not boom length.
Is there a way to have EZNEC, or another software, doing automatic
iterations until it reaches the best F/B-SWR compromise ?


MMANA does what you want and it's free.

http://mmhamsoft.amateur-radio.ca/ and I see there's a new release out.

Read this too. http://g7rau.demon.co.uk/sm5bsz/

Brian GM4DIJ
--
Brian Howie

I downloaded MMANA but I can't seem to unzip it. What program will
unzip it ? I have WinZip 7.0

Thanks
Ron WA0KDS


Brian Howie wrote:
In message , JC
writes

Thanks for help, I think I wrongly explained my problem, here is the
question:
1/ I design an antenna, for instance a 3 el 20m beam.
2/ I enter into EZNEC wires dimensions, spacing, height, source.....
3/ EZNEC calculates gain, F/B, SWR....and results are acceptable.
4/ Now let's suppose my objectives are max F/B as I have a QRM source
opposed to my favourite transmitting direction and SWR 1.5 on a given
frequency range as my transceiver is very SWR sensitive and I can't
use an
antenna tuner.
I accept changing wire lengths and spacing but not boom length.
Is there a way to have EZNEC, or another software, doing automatic
iterations until it reaches the best F/B-SWR compromise ?



MMANA does what you want and it's free.

http://mmhamsoft.amateur-radio.ca/ and I see there's a new release out.

Read this too. http://g7rau.demon.co.uk/sm5bsz/

Brian GM4DIJ

Ron wrote:

I downloaded MMANA but I can't seem to unzip it. What program will
unzip it ? I have WinZip 7.0

Thanks
Ron WA0KDS

Ron wrote:

I downloaded MMANA but I can't seem to unzip it. What program will
unzip it ? I have WinZip 7.0

Thanks
Ron WA0KDS

FWIW, FilZip unzipped it fine: one file, MMANGAL_Setup.exe. It's
possible that the zip file became corrupted when you downloaded it,
too.

Cheers,
Tom

Ron wrote:
I downloaded MMANA but I can't seem to unzip it. What program will
unzip it ? I have WinZip 7.0

Thanks
Ron WA0KDS


Brian Howie wrote:
In message , JC
writes

Thanks for help, I think I wrongly explained my problem, here is the
question:
1/ I design an antenna, for instance a 3 el 20m beam.
2/ I enter into EZNEC wires dimensions, spacing, height, source.....
3/ EZNEC calculates gain, F/B, SWR....and results are acceptable.
4/ Now let's suppose my objectives are max F/B as I have a QRM source
opposed to my favourite transmitting direction and SWR 1.5 on a given
frequency range as my transceiver is very SWR sensitive and I can't
use an
antenna tuner.
I accept changing wire lengths and spacing but not boom length.
Is there a way to have EZNEC, or another software, doing automatic
iterations until it reaches the best F/B-SWR compromise ?



MMANA does what you want and it's free.

http://mmhamsoft.amateur-radio.ca/ and I see there's a new release out.

Read this too. http://g7rau.demon.co.uk/sm5bsz/

Brian GM4DIJ

MMANA does what you want and it's free.

However, note that because MMANA being a MiniNec based program, when
using none vertical elements below 0.2 wavelengths accuracy rapidly
drops. If you'd like to optimize on (lower) HF, a Nec based program is
prefered

Furthermore, I don't think optimization is out. But, if it should be
so, it still will learn you very much about the effect of antenna
dimension changing on antenna performance.

And last but not least, because of being freeware, experimenting with
MMANA or 4nec2
[http://home.ict.nl/~arivoors/] will cost you nothing (besides a
little studying), weather you would like to use a traditional optimizer
of a genetic algorithm based optimizer.

Arie.

"JC" wrote in
:

Is there a software which can design an antenna (like EZNEC or similar
) then allows to automatically optimize its dimensions according to
given requirements: max gain, F/B, min swr... and accepted dimensional
parameters changes: boom length, spacing....
JC

http://mmhamsoft.amateur-radio.ca/fi...ANA-GAL-65.zip


--
Dave Oldridge+
ICQ 1800667