John Popelish wrote:
Cecil Moore wrote:
Please give us the equation for "ordinary AC voltage or current".

The simplest (without a reference phase) would be cos(wt). The standing
wave function contains this term, with a modifier to tell you how
amplitude varies with position. But at any point, cos(wt) times some
amplitude describes the ordinary AC voltage or current swing.

But please notice that cos(kx+wt) is different from that term.
The only time they are the same is if 'x' = 0. Is 'x' always
equal zero? No. All your equation tells us is that whatever
current it represents, it is always in phase with the reference
source at 'x' = 0. So your equation is too simple to be useful.
Please try again.

EZNEC must take those within a cycle currents and voltages into account
to come up with the amplitude values.

"Must" or "does". I have no idea.

At a given point the traveling wave phasor doesn't rotate, either.

On the contrary - at any given point 'x', the traveling wave
phasor is rotating with respect to the source phasor. That's
what makes it different from a standing wave phasor which
doesn't rotate with respect to the source phasor.

Phasor rotation only applies to the phase change over length for a
traveling wave.

No, that's wrong. Take another look at cos(kx+wt). Holding 'x'
at a constant value, the phase keeps on changing. The traveling
wave phasor is rotating with respect to the source. The standing
wave phasor is not rotating with respect to the source, just
as Hecht says speaking of standing waves: "The resultant
phasor is E1 + E2 = E ... Keeping the two [traveling wave]
phasors tip-to-tail and having E1 rotate counterclockwise as
E2 rotates (at the same rate) clockwise, generates E [total] as a
function of 't'. ... It doesn't rotate at all, and the resultant
wave it represents doesn't progress through space - it's a
standing wave."

You really need to get you a copy of Hecht's "Optics". It the
best treatment of standing waves that I have ever seen - also
best at superposition and interference explanations.

You don't add superposed RMS values to get the resultant RMS value.

Sure you do. Current #1 is an RMS value at angle 1. Current #2
is an RMS value at angle 2. The superposition is:

RMS#1*cos(A1) + RMS#2*cos(A2) = RMS(total)

There is no discussion of RMS envelope values.

Where have you been? The currents displayed by EZNEC are RMS
envelope values. The antenna currents plotted in Kraus and
Terman are RMS envelope values. The currents measured at the
top and bottom of the coils by W8JI and W7EK are RMS envelope
values.

I am waiting for you to realize that you can measure the phase shift of
each of the traveling waves that superpose in a standing wave process
that includes a coil (or any other network) by using only the RMS
amplitude envelope, with no reference to phase, in an EZNEC simulation
or a real experiment. That was the whole point that began this
discussion, wasn't it?

Yes, I said that months ago but nobody would buy the argument.
Over those months, I have given countless examples proving that
to be true. Everyone just ignored those technical facts as they
have ignored 95% of the technical content of my postings only
to concentrate on the 5% containing feelings or bad humor.

Now, measure the phase shift of that coil ...

Sorry, the coil is obviously not the problem. Everyone understands
how a coil works. What everyone doesn't understand is how standing
waves in a wire work. That will be my topic of discussion from now
on. But feel free to continue the coil topic with anyone else.
--
73, Cecil http://www.qsl.net/w5dxp

wrote:
Grow up Cecil. Everyone sees what you are doing.

Everyone should see that I am trying to discuss technical
issues while the rest of you object to the 5% of my postings
that are bad humor or complaints about how I am being
unfairly treated.

Why do you refuse to discuss technical issues? For
instance, you have avoided responding to my black box
question. Are you afraid everyone will see just
how wrong you are?

Here is it again assuming a lossless transmission line:

Source-----------a-BB-b-------------c-BB-d-----------open

The current measured at 'a' is one amp.
The current measured at 'b' is zero amps.
The current measured at 'c' is zero amps.
The current measured at 'd' is one amp.

What are the possibilities for what could be in the
black boxes?

There could be 90 degrees of transmission line in
each box.

Or there could be 90 degree coils in each box.

Or one box could contain 90 degrees of transmission line
and the other contain 90 degrees of coil.
--
73, Cecil http://www.qsl.net/w5dxp

Roy Lewallen wrote:

I see that Cecil's latest fetish is that EZNEC reports RMS values of
voltage and current. Because we know that the voltages and currents are
purely sinusoidal, the RMS value and phase angle (also reported by
EZNEC) are adequate to define the time waveform. That is, when we know
the RMS amplitude and the phase angle, we know the value of the waveform
at every instant in time. No additional information is necessary.

Since you agree with me, what's with the fetish remark?
You seem to feel obliged to take an ad hominem pot shot
every time you mention my name. I assure you, it is
hurting your reputation more than it is hurting mine.
--
73, Cecil http://www.qsl.net/w5dxp

Ok, I'll bite once more since you have put so much work into
that post.... :/

MK, that is the whole point, that you portray missing or not appreciating.

Yes. It is quite true. I don't really appreciate the importance of
knowing
if the current tapers across a coil or not. Even if I did, what could I
do about
it? But you can consider this a personal problem...

It might not matter to you, but I am sure many would benefit from knowing
more precisely what is REALLY going on and then use or correct their design
methodology.

How are you going to to fix what is not broke? There is nothing wrong
with the current state of mobile whip design. I don't see how it can be

improved without going to unpractical measures. Deciding whether or
not there is current taper across the coil is not going to help you
improve a mobile antenna one whit.
Now, I'll agree there might be other app's where it could be useful to
be aware of this, but not for mobile whips.

I think it is fine for you to ignore this and poh-poh it. But I know how
huge difference it made in my 160m mobile antenna when I extended the whip
to the front bumper with wire.

No kidding.... I've never heard of adding a longer whip to improve a
mobile antenna. :/ What does coil current taper have to do with this?
I could have told you about adding longer whips way before you even
thought
about current taper. I've never needed current taper technology to
know
that adding a longer top whip to a short mobile antenna will generally
improve
performance.
Have you ever tried Reg's "vertload"? You can play "what if" till the
cows
come home... I often have...

The lesson is, the higher you place the coil on the
radiator, the more turns you need to reresonate the radiator, the high
current portion of the antenna current distribution curve gets "stretched
up", better efficiency (larger area under the overall curve).

And this lesson is new? Get a grip...I've been aware of this for years.

And I think most others have been too...


This all is supported by reality, except "gurus" who insist that the current
is (about) the same across the coil and they make (theoretically) antenna
current to be higher across the tip and "more" efficient than it is.

You can't fool a field strength meter. It makes no difference whether
one
believes there is a taper or not, the antenna is still going to perform
the
same for a given coil height on a given height mast.


It is known how profound effect had replacement of loading stubs by coils in
the KLM 3 el. 80 m loaded Yagi. Better gain, huge improvement in the F/B and
pattern. Has been done and described. And this is just replacing the same
inductance value stub with coil, where delta current from stub wires was
enough to throw monkey wrench in the Yagi performance. Now consider larger
error from the wrong assumption or calculation caused by wrong current
magnitudes and distribution.

Not a very good example. Sure, replacing inferior stubs, or whatever
methods
of linear loading are usually going to be improved by changing to coil
loading.
No big surprise. If doing this makes a large improvement in f/b,
pattern, etc,
sounds like it was a poor design from the git go... I still don't
follow how
knowing about current taper is going to help you much here. How will
you
apply this knowledge? Will this "improved coil taper technology"
improve
performance more than 1 db? At this point, I won't be holding my
breath.


Heloooo guys!
Measure, feel, whatever, the frickin' current across the loading coil and
then come back and tell the world why it IS different, but IT CAN'T be so,
because you said so in the beginning and you just can't admit being wrong.

Dunno...I think you have me confused with someone who really gives a
hoot.
I could care less if you are right or wrong. What I want to know is how
is this
"knowledge" going to improve a mobile whip. ?
I'll grant you that there may well be cases where knowledge of this
could
be useful. Mainly when modeling very complex antennas.
But as far as the basic mobile whip, knowing about current taper across

the coil is not going to help you improve the antenna one bit.
Trying to say that it showed you that you need to add a longer
capacitive
whip to a 160m antenna is silly.
You can run "vertload" and see the appx best place for the coil very
quickly. No current taper technology will be used, yet it will be quite
accurate for most all uses.
This coil taper effect you have spent months trying to prove may seem
very important to you, but to me it's fairly ho-hum..."snore" It's
been shown
that the possible errors in modeling are going to be generally small
and usually under 1 db in most cases.
There may be something useful to come out of all this, but it ain't
going
to be an improvement of mobile antenna design. I think it's safe to
say you can take that to the bank. The optimum location of a coil
on a short whip is already well known and etched in fairly hard
material. Deciding there is current taper across the coil is not
going to change this.
MK

Since EZNEC has been mentioned so much lately, it's appropriate to point
out that it's able to calculate the current at all points along a
helically modeled loading inductor with what I believe to be very good
accuracy. And it does it without any use or knowledge of presumed
traveling voltage or current waves. It deals only with the total
current. Perhaps Cecil would benefit from investigating how this is done.

EZNEC uses NEC-2 for calculations, and the NEC-2 manual is available on
line at no cost. A detailed description of its methodology is presented
in Part I. For those who want just a general overview of the method (the
method of moments) in a more easily understood format, one can be found
in the second and later editions of Kraus' _Antennas_. I notice that
most newer antenna texts also include a description of the moment
method, and it should be available in the web as well.

Roy Lewallen, W7EL

Cecil wrote, in reply to John P.,

"Of course, *everyone* except you and Tom Donaly are talking about
charge stored over a whole cycle."

Excuse me???

Note Cecil's emphasis on "everyone". Note that this was posted AFTER I
had repeatedly told him that _I_ was not talking about 'charge stored
over a whole cycle'. I'm offended that Cecil would fail to acknowledge
me as not being in the "everyone" group. I'll let others speak for
themselves, but I'd put pretty good odds that several others will be
crystal clear about not being included in that "everyone."

Roy Lewallen wrote:
And it does it without any use or knowledge of presumed
traveling voltage or current waves.

Thanks for the reference, Roy, I'll take a look at it.

One wonders how EZNEC tells the difference between a
standing wave antenna and a traveling wave antenna
"without any use or knowledge of presumed traveling
voltage or current waves".

I'm willing to bet it doesn't use lumped circuit
theory. :-) I'm also willing to bet that forward
and reflected waves are taken care of in the
equations used by NEC.
--
73, Cecil http://www.qsl.net/w5dxp

K7ITM wrote:

I beg your pardon? Excuse me? I "trimmed out all the technical
content and didn't quote anything you said"???

Yes, and you are doing it again. I'm quoting your entire posting
and there is not one quote from me.

As a matter of fact, I
took exactly the numbers you gave us, ALL of them, and used them and
ONLY them in my accounting. If THAT's "disembodied from reality," then
I'd point out that it's YOUR numbers that are disembodied from reality.
In fact, I didn't argue with YOUR numbers at all. I just took them at
face value. You were the one that discarded what I carefully developed
from them without out so much as an ounce of reasoning or explanation.
After that I went on to FURTHER EXPLAIN why I had done what I did in
the first place, and you dismissed that again without any technical
explanation.

It's all there for everyone to see, Cecil.

If there's a quote from me in this posting, Tom, I am unable
to find it.

Go ahead, dig yourself deeper into it.

Since you didn't quote anything I said, I have no idea what
you are talking about.
--
73, Cecil http://www.qsl.net/w5dxp

You really think so, Cecil?? I saw through it the first time you
posted it. As an EZNEC and NEC2 user, I know that not only the current
magnitude, but also its phase, is reported. I knew that what you
posted about it was incorrect. I don't see Roy's comment as agreeing
with you at all, but completely disagreeing. You said that it only
gave amplitude information, when in fact it gives phase and amplitude.

K7ITM wrote:

Cecil wrote, in reply to John P.,

"Of course, *everyone* except you and Tom Donaly are talking about
charge stored over a whole cycle."

It sure would be nice if you made your attributions conform
to netnews guidelines. I cannot tell what you are responding
to since your attributions are all screwed up.

Excuse me???

Note Cecil's emphasis on "everyone". Note that this was posted AFTER I
had repeatedly told him that _I_ was not talking about 'charge stored
over a whole cycle'. I'm offended that Cecil would fail to acknowledge
me as not being in the "everyone" group. I'll let others speak for
themselves, but I'd put pretty good odds that several others will be
crystal clear about not being included in that "everyone."

I obviously got my "Tom's" mixed up. There's three of you here
and it's likely a common mistake. I profusely apologize and don't
know what else I can do to rectify my mistake.

If there were two Cecil's here and you got us mixed up, I wouldn't
get my panties bunched into a wedgie because of that.
--
73, Cecil http://www.qsl.net/w5dxp