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Old July 23rd 03, 03:56 PM
Yuri Blanarovich
 
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Default 4NEC2 features wanted

Arie,
One more thing comes to mind, it would be desirable to be able to use insulated
wires in models. Typically house electrical insulated wire has about 5%
shortening coefficient. I think it would suffice to enter the shortening
coefficient (can be obtained by measurement). I believe NEC4 can accomodate
that and could serve as an example how to do it.
Also different material for elements within antenna, like copper (insulated)
wire quad and aluminum Yagi elements.

That's it besides transducer for the brain to "see" the design in my head and
optimize/model it in 3D :-)

Yuri, K3BU



me wrote befo

Arie 4NEC2 wrote:

I would be very glad to know what you think could be added to 4nec2 to
make it even better.


Thanks again for fine software Arie.
Things I would like to see is incorporation of terrain simulation with antenna
design. Few zones of different "ground quality" (radials, sand, salt water)
with linear and/or circular boundaries plus sloping terrain (contour profile).
Example would be four square array on the sloping hill of sand some distance
from the ocean. Verticals are very sensitive to the ground quality and terrain
slopes/profile and this feature would be a great tool in quest for maximizing
the performance of array by using the terrain features (enhanced F/B).
K6STI has Terrain Analyzer (?) I have never tried it, but I understand that he
uses free space pattern of antenna and then applies the geometry and quality of
ground. I can see that more true representation of antenna's performance is to
tweak the design with real ground/terrain situation. Vertical antennas, where
ground participation makes significant difference in the tuning of array, would
be more closely modeled by using real ground rather than free space (who's got
it anyway?) and then doing optimization with given ground/terrain situation.
Enough challenge? I don't know of any software that would do optimization with
participation of ground/terrain.
Thanks again!

Yuri, K3BU

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Old July 24th 03, 04:31 AM
Dale Parfitt
 
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Yuri Blanarovich wrote:

Arie,
One more thing comes to mind, it would be desirable to be able to use insulated
wires in models. Typically house electrical insulated wire has about 5%
shortening coefficient. I think it would suffice to enter the shortening
coefficient (can be obtained by measurement). I believe NEC4 can accomodate
that and could serve as an example how to do it.
Also different material for elements within antenna, like copper (insulated)
wire quad and aluminum Yagi elements.

That's it besides transducer for the brain to "see" the design in my head and
optimize/model it in 3D :-)

Yuri, K3BU


Hi Yuri,
W4RNL has a very nice tech note on his site relating this shortening effect with
respect to the thickness of the dielectric and its dielectric constant. I used this
on my latest 20M Moxon and it came out right on the money.

Dale W4OP

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Old July 25th 03, 04:13 AM
Yuri Blanarovich
 
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Howdy Arie and fans,

Dale W4OP, found the link to W4RNL dissertation on modeling insulated wires at
http://www.cebik.com/amod/amod50.html
which shows how NEC4 engine considers insulated wires.

Among other things on the page I have found that I was not of the rocker after
all, when I was talking about the "electrical length" of conductors used in the
antenna. I was "grounded" by some NG purists that IEEE dictionary or reference
books do not use or mention that term. To me it made perfect sense, just as
with coax and feedlines. If we are looking for the resonant or corresponding
electrical length of the "wire" we know that we can end up with different
physical length for the same frequency between the thick tubing and thin wire.
This is important especially when dealing with parasitic arrays, where resonant
or electrical length is important and physical length can be then derived from
it to maintain proper function of the array.

Here is what W4RNL 'splains also:
For a long time, antenna builders have been aware that insulated antenna
element wire has a velocity factor. The electrical length of an insulated wire
will be longer than the physical length to a degree that depends upon the type
and thickness of insulation. Expressed from a different perspective, a resonant
dipole for some given frequency and wire diameter will be shorter if the wire
is insulated than it will be if the wire is bare. How much shorter the
insulated dipole will be depends on the insulation.

So feel free to use the term, no need for royalties.
I feel not SoDumb :-)

Yuri, K3BU


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Old July 25th 03, 11:40 AM
 
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oSaddam (Yuri Blanarovich) wrote in message ...
Arie,
One more thing comes to mind, it would be desirable to be able to use insulated
wires in models. Typically house electrical insulated wire has about 5%
shortening coefficient. I think it would suffice to enter the shortening
coefficient (can be obtained by measurement).


Nice suggestion. However I did not write my own nec-2 core, just used
the existing nec-2 sources and changed it a bit to integrate the nec-2
calculations and the sommerfeld ground calc's.

However there is another freeware program available which uses the
nec-2 and for which it is possible to specify insulated wires. From my
memory, I think I saw this on Ray Andersons 'unofficial nec' pages.

I believe NEC4 can accomodate
that and could serve as an example how to do it.


One of my great wishes would be nec-4 becoming (public) available for
none american citizens. However I am already waiting for it some four
or five years, and I have no indications this will change soon.

Also different material for elements within antenna, like copper (insulated)
wire quad and aluminum Yagi elements.


4nec2 makes is possible to use almost any nec2 card. So there is no
provblem specifying different materials for different parts of the
antenne or for the antenna as a whole. When using the CAD style
geometry editor, one has predefined list-boxes available with common
materials.

That's it besides transducer for the brain to "see" the design in my head and
optimize/model it in 3D :-)


During optimization you can see the 3D model change, as it is updated
every iteration (if this is the right english word for it..).

Arie.
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Old July 25th 03, 12:05 PM
[email protected]
 
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oSaddam (Yuri Blanarovich) wrote in message ...
Arie,
One more thing comes to mind, it would be desirable to be able to use insulated
wires in models. Typically house electrical insulated wire has about 5%
shortening coefficient. I think it would suffice to enter the shortening
coefficient (can be obtained by measurement).


Somehow I managed to let my first reply on this subject disappear
completely, so let's give it another try....

***

4nec2 was based on the 'standard' nec-2 core for which I only merged
the separate nec-2 and sommerfeld executables into one single
executable file to be able to use 'sommerfeld ground' inside a
frequency sweep.

The original nec-2 sources contain no provision to handle insulated
wire, but I beleave on
www.qsl.net/wb6tpu/swindex.html there is
another freeware program available for handling insulated wires with
nec-2.

I believe NEC4 can accomodate
that and could serve as an example how to do it.


Yes. One of my great wishes is nec-4 (sources) becoming available for
none-american citizens. I am still waiting for this some four or five
years but I am afraid I will have to wait at least another 4 years.

Also different material for elements within antenna, like copper (insulated)
wire quad and aluminum Yagi elements.


4nec2 supports most of the nec-2 cards, so it is no problem to specify
different materials for any part of the antenna oR for the structure
as a whole. When using the CAD based geometry editor a pre-defined
list of common materials is available.

That's it besides transducer for the brain to "see" the design in my head and
optimize/model it in 3D :-)


??

Arie.


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Old July 25th 03, 04:29 PM
Art Unwin KB9MZ
 
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Dale Parfitt wrote in message Arie

Arie
As a retired person I do not have enough time for a lot of things so
as yet have not looked at your program. ( Old people have so many
projects but always under estimate the time required because
abilities deteriate as age progresses)
Could you tell me if you have the ability to make an impedance value
a variable which could be helpfull when designing loops?
Also, how many variables do you have available together with max
number of pulses used ? Since close coupling of wires can be very
sensitive to change, to me the above factors would be all important.
I would add however, that coupling is not viewed seriously in ham
radio so attempts to provide such features would provide little if
any reward.
Again thank you for all the work you have done on a sharing basis
to keep this hobby so interesting
Regards
Art


...
Yuri Blanarovich wrote:

Arie,
One more thing comes to mind, it would be desirable to be able to use insulated
wires in models. Typically house electrical insulated wire has about 5%
shortening coefficient. I think it would suffice to enter the shortening
coefficient (can be obtained by measurement). I believe NEC4 can accomodate
that and could serve as an example how to do it.
Also different material for elements within antenna, like copper (insulated)
wire quad and aluminum Yagi elements.

That's it besides transducer for the brain to "see" the design in my head and
optimize/model it in 3D :-)

Yuri, K3BU


Hi Yuri,
W4RNL has a very nice tech note on his site relating this shortening effect with
respect to the thickness of the dielectric and its dielectric constant. I used this
on my latest 20M Moxon and it came out right on the money.

Dale W4OP

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Old July 28th 03, 05:37 PM
Yuri Blanarovich
 
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Default

Yuri
Arie


I believe NEC4 can accomodate
that and could serve as an example how to do it.


Yes. One of my great wishes is nec-4 (sources) becoming available for
none-american citizens. I am still waiting for this some four or five
years but I am afraid I will have to wait at least another 4 years.


Same here, more problem of time, trying to master other programs and get good
grip on them, before getting too serious with NEC4.

Also different material for elements within antenna, like copper

(insulated)
wire quad and aluminum Yagi elements.


4nec2 supports most of the nec-2 cards, so it is no problem to specify
different materials for any part of the antenna oR for the structure
as a whole. When using the CAD based geometry editor a pre-defined
list of common materials is available.


I should try that. As I see all those things are important to be included for
more precise cxalculations and especially with optimizers. Otherwise some short
cuts have to be used to approximate the conditions.

Just keep it in your to do file, maybe some day...


Tnx 73 Yuri
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