Sal M. Onella wrote:

...
Well, well, well! Two men who would otherwise be generating admiration are
in a hair-salon slap fight. Nobody cares but I'm putting this group on
hiatus. Phooey!

Well, well, Mr. Samonella, shame ta' see ya' go, and yer sorry donkey
will be missed ... bye ... gesus, if we begged, would ya' stay? :-O

JS

I've always regarded email as being private and confidential, and I'm
sorry to see that Cecil doesn't give it the same respect. My email to
Cecil was correctly quoted. However, as so often seems to happen, the
context wasn't accurately reported. I provide support for all EZNEC
customers, including Cecil, as I always have. And I choose not to engage
Cecil in pointless and endless argument about his alternative theories,
either in this newsgroup or by email.

Roy Lewallen, W7EL

Sal M. Onella wrote:
"-------------" ---------------.com wrote in message
. net...
-----------------wrote:
But if anyone is
actually seriously interested in investigating alternative theories or
analytical methods, NEC or derivative programs such as EZNEC can provide
powerful assistance in confirming or refuting them.
Here is an email response from -------------, when I used
EZNEC to disprove his invalid coil current measurements.
He apparently didn't like the EZNEC results from this file:

http://www.-------------/coil512.EZ

---------------------wrote on May 12, 2007:
I resent your trying to use EZNEC support as a surreptitious
way to continue pushing your junk science on me. If you send
me one more non-support related email, I'll put you on my spam
list so your messages won't even make it to my ISP and I won't
have to waste any more of my time on you. That'll mean no more
EZNEC support, and I'll refund your EZNEC purchase price. So go
ahead, send me one more non-support email and make an easy $149.00.
----- previously posted my private email without my permission
so turn about is fair play.
--
73, ------ http://www.---------.com

Well, well, well! Two men who would otherwise be generating admiration are
in a hair-salon slap fight. Nobody cares but I'm putting this group on
hiatus. Phooey!

Roy Lewallen wrote:

...
Well, well, well! Two men who would otherwise be generating
admiration are
in a hair-salon slap fight. Nobody cares but I'm putting this group on
hiatus. Phooey!



When I was younger, I read articles by Roy--seriously.

"His program" EZNEC is a noteworthy contribution to "antenna
builders"/amateurs--I find, concretely, this cannot be debated ...

Simply the end of the story ... now, many other things exist too ... if
"things seem differently", so be it.

Nuff' said ... I'd go further even, Roy got me my extra--while not
directy, maybe, he did!

Regards,
JS

Cecil Moore wrote:
Ian White GM3SEK wrote:
However, any valid explanation of practical loading coils must
predict zero phase shift for the boundary condition where the coil
displays no other properties except pure inductance.

Translation: A model must accommodate conditions that
are impossible to achieve in reality. I'm sorry, Ian,
but that is pathological thinking not uncommon on this
newsgroup.

No, Cecil, that is a complete MIStranslation of what a boundary
condition is.

A software model that blows up when R=0 is perfectly
acceptable in the real world. It is a software bug,
not a statement on reality.

It's only your model that blows up. If your model sees lumped-component
behavior as an impossible singularity, that cannot be correct.

Other people's models of antenna loading do not have this problem. They
recognise that lumped inductance is often a good approximation to
reality, so they very sensibly use that as their starting-point. Then
they can progressively apply corrections for the distributed properties
of a real-life inductors. The smaller those corrections are, the simpler
the model becomes.

In practical terms, a lumped-inductance model will take you straight to
a buildable prototype. The necessary corrections can then be applied by
mechanical adjustment, without needing to model the distributed
properties of the loading coil in detail. Such models are to be found in
G4FGQ's MIDLOAD program, ON4UN's 'Antennas for Low Band DXing' and other
handbooks.

There was also an excellent theoretical treatment by Boyer in 'Ham
Radio', which shows in detail how the model of an antenna as an
unterminated transmission line is COMPLETELY capable of incorporating
lumped inductance:
The Antenna-Transmission Line Analog, 'Ham Radio', April and May 1977.



--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

"-------------" ---------------.com wrote in message
. net...
-----------------wrote:
But if anyone is
actually seriously interested in investigating alternative theories or
analytical methods, NEC or derivative programs such as EZNEC can provide
powerful assistance in confirming or refuting them.

Here is an email response from -------------, when I used
EZNEC to disprove his invalid coil current measurements.
He apparently didn't like the EZNEC results from this file:

http://www.-------------/coil512.EZ

---------------------wrote on May 12, 2007:
I resent your trying to use EZNEC support as a surreptitious
way to continue pushing your junk science on me. If you send
me one more non-support related email, I'll put you on my spam
list so your messages won't even make it to my ISP and I won't
have to waste any more of my time on you. That'll mean no more
EZNEC support, and I'll refund your EZNEC purchase price. So go
ahead, send me one more non-support email and make an easy $149.00.

----- previously posted my private email without my permission
so turn about is fair play.
--
73, ------ http://www.---------.com

Well, well, well! Two men who would otherwise be generating admiration are
in a hair-salon slap fight. Nobody cares but I'm putting this group on
hiatus. Phooey!

Owen Duffy wrote:

Roy,

Aren't limitations on segment size an issue, especially with small diameter
coils?

Although NEC has recommended limits on both minimum and maximum segment
length, my experience is that the minimum can often be disregarded with
no apparent degradation of the result. A good test is a small
single-turn loop, for which the theoretical result is well known. There
is a limit to NEC's ability to model a single turn loop for reasons
other than segment length, but the result holds very well for very short
segments. A more important criterion is the segment length to wire
diameter (or radius) ratio. Results begin getting poor when the segment
starts looking like a coin, that is, with a segment length considerably
smaller than the wire diameter. EZNEC spots these conditions and issues
appropriate warnings via its guideline check. Most errors caused by
segmentation problems show up in a poor average gain.

Can NEC model a typical HF helically loaded mobile whip reasonably, sy 16mm
diameter, 1.2m long with variable pitch progressing to close spaced turns
on the top 30% or so?

There's no provision in either NEC or EZNEC to automatically generate a
helix with variable pitch, but you could make a stepped approximation
with several tandem helices. However, if by "close spaced turns" you
mean wires which touch or nearly touch except for the insulation, this
violates the rule I stated earlier, that the distance between outsides
of wires should be at least one wire diameter, and preferably several.
So the coil as you describe it can't be accurately modeled. As long at
the rule is followed, though, NEC or EZNEC should be able to do a good
job of modeling a fairly typical whip loading coil.

I suspect NEC is not a magic bullet either.

Because EZNEC uses NEC for calculations, they both have nearly the same
limitations. I say "nearly" because EZNEC does have some added
protection against very small or large intermediate values in some
calculations, fixes for a few special cases, and minor changes from NEC
for various reasons. Most users are unlikely to see the effects of any
of these, however.

No modeling program, regardless of what's being modeled or how, is a
"magic bullet". Every last one has limitations and requires knowledge,
skill, and often a bit of art to utilize effectively and without a good
probability of serious error. I spend a lot of time and effort here, via
customer support, in the EZNEC manual, and in other venues, bringing
attention to EZNEC's limitations in the hope that it will save users
from getting results which are thought to be valid but aren't.

Side note: I had forgotten that at least one of the copies of NEC-2 I
have includes a GH 'card' provision, so the modification is apparently
quite common. It's not mentioned in the NEC-2 manual I have, however.

Roy Lewallen, W7EL

John Smith wrote:

...
Nuff' said ... I'd go further even, Roy got me my extra--while not
directy, maybe, he did!

Regards,
JS

directy = directly, but then, ya already knew that ...

Well, ya' know what I mean, hard to argue with a personality that was
there (well, in spirit) when ya' built yer' first CPO (Code Practice
Oscillator--fer' all ya' newbies.)

Thinkin' about it, Roy is a REAL amateur ... and again, nuff' said. I
wish I'd have saved all those magazines.

When I "argue" with/idead/him, it is in the fondest of ways ... but
then, yas' already knew that ... good night Roy.

Real men have strange ways and they don't need explained ...

....

Warm regards,
JS

Roy,

Thanks for the exhaustive answer.

I appreciate your opinion on the short segment issue. I must admit
playing with it and not noticing things go pear shaped as frequency was
reduced (so that segment length become relatively short).

To those of us that haven't dived into the internals, the warnings are a
concern and prima facie, I would be reluctant to accept and use results
from a model with unresolved warnings.

The helical problem I posed is not unusual, many if not most low HF
helicals wind up with close spaced turns at the top, and the absence of
model accuracy in that part of the antenna renders any model of very
limited value. (I am not suggesting that the Corum approach can deal with
a variable pitch helical with close spaced turns at the top either.) It
is just a real implementation that seems a problem to model.

So, NEC can model your helical so long as your helical is one that NEC
can model!

I am familiar with the GH card, Arie's 4NEC2 has it. I think my version
of EZNEC can generate a helix, but I know that it cannot save a NEC
compatible deck.

I have tried a NEC-2 model of the coil that Tom described with 8
segments/turn (warning: segment length = 0.00013wl). The inductive
reactance is a little different to the Hamwave Corum based calculator,
the R is very different, the self resonance is different (understandably,
likely to be affected by the coil terminations) and we don't know a
measured value for Tom's coil anyway or the true stand alone self
resonance.

Owen

Owen Duffy wrote:
. . .
The helical problem I posed is not unusual, many if not most low HF
helicals wind up with close spaced turns at the top. . .

Out of curiosity, why?

Roy Lewallen, W7EL

Roy Lewallen wrote:

...
Roy Lewallen, W7EL

Great little piece of software, but, want something free without the
restrictions?

http://mmhamsoft.amateur-radio.ca/mmana/index.htm

By amateurs, for amateurs--wouldn't be surprised it it used the same
engine a EZNEC--or, that EZNECS' gui used the same engine!

Regards,
JS