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-   -   Lumped Load Models v. Distributed Coils (https://www.radiobanter.com/antenna/1140-lumped-load-models-v-distributed-coils.html)

Tdonaly January 31st 04 07:32 PM

Cecil wrote,

Tdonaly wrote:
O.k., Cecil, let's suppose you're right. Since there's more
current going into a coil than coming out, then the coil must be
storing charge, somewhere.


Tom, Tom, Tom, we are talking about *net* current. The net current
in an unterminated transmission line can be zero while 1/4WL away,
it is 100 amps. Are you asserting that transmission lines don't
conserve charge? Would you please put your brain in gear?
--
73, Cecil http://www.qsl.net/w5dxp


That's a pretty incoherent post, Cecil. It's tough to have a good
argument with you if you won't take the time to understand what
I write. Maybe you're trying to sucker me into another 500 post
marathon. Forget it, my doctor says I have to eschew effort.
I'll attack your ideas again sometime when something else interesting
comes up. Otherwise, I'll just be chewing muh cabbage twice.
73,
Tom Donaly, KA6RUH



Cecil Moore January 31st 04 07:37 PM

Tdonaly wrote:
yes, we do, but you can't get the monkeys to perform
unless you rattle their cage.


Last time I checked, it was the monkeys who believe that a
two wavelength helical antenna doesn't have any phase changes.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore January 31st 04 07:39 PM

Gene Fuller wrote:
I am merely commenting on the highly unscientific handwaving approach
taken RRAA's most prolific "scientist".


Quoting an accepted expert author is handwaving?????????????
Do you also believe that there are no phase changes in a
two wavelength long helical antenna?
--
73, Cecil http://www.qsl.net/w5dxp



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Richard Clark January 31st 04 07:41 PM

On 31 Jan 2004 19:32:18 GMT, (Tdonaly) wrote:
I have to eschew

Gesundheit

Tdonaly January 31st 04 07:47 PM

Gene wrote,

Cecil,

This has become unusually entertaining.

You have declared experimentation to be unnecessary, e.g., your Diamond
antenna
story. You have declared math models to be unnecessary and incorrect on
numerous
occasions.

I have worked with a lot of scientists in my career; some were experimentally

biased, some were theoretically biased, and many understood that both
approaches
were useful.

However, I do not believe I have ever encountered a "scientist" who rejected
both experimental and mathematical approaches at the same time.

73,
Gene
W4SZ


Gene, people who come up with simple "my easy-to-understand,
the-scientists-think-
they-know-everything-but-don't" theories usually don't have much use for either

mathematics or experimentation. Indeed, why should they? Since the theories
they've
thought up in their heads already explain everything, mathematics and
experimentation are
merely redundant. It's the same logic that was used to burn what was left of
the
library at Alexandria (after the Christians had destroyed most of it, already):
everything
you need to know is in the Koran, so these books are useless.
73,
Tom Donaly, KA6RUH



Cecil Moore January 31st 04 07:48 PM

Tdonaly wrote:

Cecil wrote,

Tdonaly wrote:
O.k., Cecil, let's suppose you're right. Since there's more
current going into a coil than coming out, then the coil must be
storing charge, somewhere.


It's tough to have a good argument with you if you won't
take the time to understand what I write.


At the point in the cycle where the voltage on the capacitor is zero,
all of the charge is *stored in the coil*. At the point in the cycle
where the current through the coil is zero, all the charge is stored
in the capacitor. I assumed you already knew that.
--
73, Cecil http://www.qsl.net/w5dxp



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Richard Clark January 31st 04 07:52 PM

On 31 Jan 2004 17:24:18 GMT, oUsama (Yuri Blanarovich)
wrote:

The reality is that current is different, Eznec can't model it


Hi Yuri,

I would suggest that you visit a very informative site that says quite
the opposite with:
Roy Lewallen, W7EL, author of EZNEC and Richard Clark, KB7QHC
recommend workarounds to replace the coil with cylinder of similar
size or breaking the coil to number of physical segments with appropriate inductances.


This may be found at:
http://www.k3bu.us/loadingcoils.htm

73's
Richard Clark, KB7QHC

Cecil Moore January 31st 04 08:24 PM

Tdonaly wrote:
Gene, people who come up with simple "my easy-to-understand,
the-scientists-think-they-know-everything-but-don't" theories ...


More hand-waving ad hominem attacks instead of one iota of
scientific evidence that Kraus is wrong? Tom, how many
electrical degrees does an electrical 1/2WL helical
antenna occupy? Could it be that there is a 180 degree
phase shift in the current from end to end?
--
73, Cecil http://www.qsl.net/w5dxp



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Yuri Blanarovich January 31st 04 09:45 PM

The reality is that current is different, Eznec can't model it, ...

Yuri, have you read Wes's article? Using wire segments, he modeled a loading
coil in EZNEC. His segmented wire model of a coil shows a current taper
through the coil. It's on his web page at: http://www.qsl.net/n7ws
You can also download Wes's zipped EZNEC files.
--
73, Cecil http://www.qsl.net/w5dxp



Sorry!
OK, I will be more precise:
Eznec can't model current through zero physical size, but certain value
inductance inserted in the antenna element. (As W8JI shows on his web page
modeling his mobile antenna, "proving" that current is the same :-)
If the inductance is modeled as coiled wire with numerous segments and proper
physical dimensions, then the current is modeled and reflects the reality.
(Tough to do modeling typical loading coils.)
How's that?
Sorry I got pulled into the simplificity :-)
LB Cebik on his web site also has an example of coil modeled using segments and
it shows current drop.

I hope it warms up, so I can get out, dig the car from the snow and do some
experimenting.

First experiment will be with 80m Hustler coil in order to use "standard"
(lousy) typical coil. I will paste LCD strip thermometers on the coil to
measure temperature changes at various positions, ends, middle.

Experiment #1:
I will drive DC current through the coil in order to generate heat and observe
the temperatures across the coil. I predict that thermometers will be tracking
each other very closely or be identical (ideal case).

Experiment #2:
I will insert the same coil in the Hustler mobile antenna, tune to resonance
and fire 100W to it. I will observe temperatures between the end and center and
between two ends. I expect difference indicating difference in current at
various points.

This will be the least disturbing measurement setup, no conductive nothing
disturbing the coil or antenna. I am assuming LCD thermometer is RF transparent
and I will verify that it does not detune the antenna/coil. Perhaps not very
accurate, but sufficient to demonstrate the debated differences.
The next measurements will be with current probes and RF ammeters. This will
give more accurate values.

Any problems with that?

Yuri, K3BU.us

Art Unwin KB9MZ January 31st 04 09:48 PM

Cecil

Did you find something wrong with my suggestion above?
I might also add that when considering coupling to a inductance the multiple
placement of inductors does not help a bit since the coupling distance has
no real reference points even tho one may decide the radiating member is the
same diameter of the coil. This is why I suggested the new aproach.
I would be very interested in any errors that you may spot in any part of
the above where a dimensionless
inductance is changed to one with actual dimensions.
Regards
Art


"Cecil Moore" wrote in message
...
Cecil Moore wrote:
I just looked at the paper again and I don't see any files to download.
Where are the files? I only have DOS-based EZNEC. Will it still work?


Sorry Wes, the combination of a small screen, color-blindness, and
cataracts causes me to miss a lot of things. I have successfully
downloaded your zip files now.
--
73, Cecil http://www.qsl.net/w5dxp



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