Cecil Moore wrote:
Tom Donaly wrote:
I don't blame him for plonking you. You're saying that because you
fantasized that Roy would make a mistake that Roy would never make,
that he also made the same mistake when measuring the delay through a
coil.

Sorry Tom, that is a diversion. The subject is NOT the delay
through a coil. The present subject is the delay through a
straight wire which is well understood. Please deal with the
topic at hand. If you refuse, we will know that you are not
sincere as far as technical facts are concerned.

Please ask Roy to prove that the current on a standing wave
antenna can be used to measure the delay through a straight
piece of wire that is x degrees long. If so, exactly how is
it done?

Roy is NOT omniscient. He definitely made the mistake but
like most gurus, refuses to admit it. You want to sweep the
mistake under the rug through diversions but I won't allow
you to do that. Once you and Roy admit that the current on
a standing wave antenna cannot be used to calculate delay,
everything else will become clear.

Please feel free to contact Roy by private email to resolve
the issue. Roy has, so far, simply stuck his head in the
sandbags and refused to respond. I'm sure he would have
advised you to plonk me instead of engaging me, for fear
of being proved wrong.

Yet, he admitted years ago that the phase of current in a
standing wave antenna varies by a very small amount. He
is presently trying to have his cake and eat it too. In
the process, he (and you as a supporter) are hoodwinking
the unwashed masses. Shame on all of you.

No, it's not a diversion. You're making up things in your head.
The original controversy involved a claim by you that the coil in
a short, mobile antenna made up for the degrees lost in said
shortened antenna. You were wrong. Now you've changed the subject to
a half wave dipole, attributing to Roy a position he would never take.
That's an old, stupid trick a woman might use in a domestic argument,
but it won't work here. I know you have a pathological need to
win every argument (you ought to talk that over with your analyst) but
that's no reason anyone should waste time agreeing with you.
73,
Tom Donaly, KA6RUH

Tom Donaly wrote:

I'm going to break my reply up into two pieces. First I
will address the actual number of degrees occupied by
a loading coil.

No, it's not a diversion. You're making up things in your head.
The original controversy involved a claim by you that the coil in
a short, mobile antenna made up for the degrees lost in said
shortened antenna.

Sorry Tom, that is a false statement. Please stop misquoting
me. The coil occupies some number of degrees but not nearly
enough to make up for all of the "lost" degrees which are not
lost at all as I have demonstrated in the past and will do so
again here. Following is a *resonant open-circuit 1/4WL stub*
that is electrically 90 degrees long yet it is only physically
38 degrees long.

Z1
---19 deg 450 ohm feedline---+---19 deg 50 ohm feedline---open
-j145

The 450 ohm feedline occupies 19 degrees of the stub. The 50
ohm feedline occupies 19 degrees of the stub. The stub is
physically 38 degrees long total. It needs another 52 degrees
to make it electrically 1/4WL long and resonant. The "lost"
52 degrees is *not lost at all* and occurs abruptly at the
junction point '+'. Call the impedance at that point Z1. The
52 degrees of phase shift occurs between Z1/450 and Z1/50.
Microsmith says that Z1 = -j145.

Z1/450 = -j145/450 = -j0.3222

Z1/50 = -j145/50 = -j2.9

Take a look at the number of degrees between -j0.3222 and
-j2.9 on a Smith Chart. Surprise! There is the "lost" 52
degrees. Those degrees are not lost at all and are just
a fact of physics concerning phase shifts at an impedance
discontinuity.

Now if we multiply the stub impedances by 10, we have
a reasonable facsimile of a resonant base-loaded monopole.

19 deg coil
///////////////-----19 deg ~500 ohm stinger-----open
Z0= ~4500 ohms
VF= ~0.02

The loading coil occupies 19 degrees and the stinger
occupies 19 degrees. There is a 52 degree phase shift
at the coil to stinger junction. There are no "lost"
degrees. 19+52+19 = 90 degrees.

There were (are) two sides to the argument.

1. The coil furnishes the "lost" degrees.
FALSE!
The coil furnishes some number of degrees but not
nearly enough to make up for the phase shift at
the coil/stinger junction.

2. The coil supplies almost zero degrees.
FALSE!
The phase shift at the coil/stinger junction is not
enough to account for the "lost" degrees. The magnitude
of that phase shift is easily calculated on a Smith Chart.

Please skip the ad hominem attacks and use the laws
of physics and mathematics to prove me wrong.
--
73, Cecil, w5dxp.com

Cecil Moore wrote:

For anyone interested in an in-depth look at the
subject of loading coils, here is an excellent
reference.

http://www.g3ynh.info/zdocs/magnetics/part_1.html

"When modeling and using inductive devices, it is
important to be aware that the concept of lumped
inductance is only strictly applicable at low
frequencies."

"In the high-frequency region, it is no longer possible
to treat the coil as though its reactance is purely
inductive; the reason being that a wave emerging from
the coil is now significantly delayed, and therefore
has a phase which differs from its phase on entry."
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Cecil Moore wrote:
Tom Donaly wrote:

I'm going to break my reply up into two pieces. First I
will address the actual number of degrees occupied by
a loading coil.

No, it's not a diversion. You're making up things in your head.
The original controversy involved a claim by you that the coil in
a short, mobile antenna made up for the degrees lost in said
shortened antenna.

Sorry Tom, that is a false statement. Please stop misquoting
me. The coil occupies some number of degrees but not nearly
enough to make up for all of the "lost" degrees which are not
lost at all as I have demonstrated in the past and will do so
again here. Following is a *resonant open-circuit 1/4WL stub*
that is electrically 90 degrees long yet it is only physically
38 degrees long.

Z1
---19 deg 450 ohm feedline---+---19 deg 50 ohm feedline---open
-j145

The 450 ohm feedline occupies 19 degrees of the stub. The 50
ohm feedline occupies 19 degrees of the stub. The stub is
physically 38 degrees long total. It needs another 52 degrees
to make it electrically 1/4WL long and resonant. The "lost"
52 degrees is *not lost at all* and occurs abruptly at the
junction point '+'. Call the impedance at that point Z1. The
52 degrees of phase shift occurs between Z1/450 and Z1/50.
Microsmith says that Z1 = -j145.

Z1/450 = -j145/450 = -j0.3222

Z1/50 = -j145/50 = -j2.9

Take a look at the number of degrees between -j0.3222 and
-j2.9 on a Smith Chart. Surprise! There is the "lost" 52
degrees. Those degrees are not lost at all and are just
a fact of physics concerning phase shifts at an impedance
discontinuity.

Now if we multiply the stub impedances by 10, we have
a reasonable facsimile of a resonant base-loaded monopole.

19 deg coil
///////////////-----19 deg ~500 ohm stinger-----open
Z0= ~4500 ohms
VF= ~0.02

The loading coil occupies 19 degrees and the stinger
occupies 19 degrees. There is a 52 degree phase shift
at the coil to stinger junction. There are no "lost"
degrees. 19+52+19 = 90 degrees.

There were (are) two sides to the argument.

1. The coil furnishes the "lost" degrees.
FALSE!
The coil furnishes some number of degrees but not
nearly enough to make up for the phase shift at
the coil/stinger junction.

2. The coil supplies almost zero degrees.
FALSE!
The phase shift at the coil/stinger junction is not
enough to account for the "lost" degrees. The magnitude
of that phase shift is easily calculated on a Smith Chart.

Please skip the ad hominem attacks and use the laws
of physics and mathematics to prove me wrong.
--
73, Cecil, w5dxp.com

I don't have to prove you wrong, Cecil, you have to prove yourself
right since you came up with this novel way of explaining antenna
behavior. A false analogy won't prove you right, in any case. Anyway,
this has all been chewed over before, and you've already used your hick
style argumentative techniques to little avail. It's too bad some
amateurs take you seriously enough to believe this garbage. They'd do
a lot better, and know a lot more if they'd learn the techniques and
mathematics found in innumerable books on the subject.
73,
Tom Donaly, KA6RUH

Tom Donaly wrote:
I don't have to prove you wrong, Cecil, you have to prove yourself
right since you came up with this novel way of explaining antenna
behavior.

I have offered a proof with which I detect no technical
problems and nobody has offered any valid technical argument
against what I have presented. My argument is not novel
and is based on sound physics as presented by the technical
references I have provided.

What I find difficult to understand is the sandbagging
going on in defense of an old wives' tale.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Cecil Moore wrote:

What I find difficult to understand is the sandbagging
going on in defense of an old wives' tale.

Your description of the phenomenon is exactly that. Your claims about
standing wave current are unadulterated bull crap. Your understanding
of wave phenomena is significantly flawed in certain respects. You
refuse to recognize where you have erred, and you fend off criticism by
making ludicrous accusations of other people. With all due respect your
behavior is absolutely pathological, which unfortunately, tend to negate
the value in any valid arguments you might otherwise make.

Although some people do occasionally attempt to correct you where you
have made a mistake (others have given up trying), they are not 'out to
get you'. Try to keep it all real and in perspective, OM.

jk ac6xg

Jim Kelley wrote:
Your claims about
standing wave current are unadulterated bull crap.

You are certainly free to produce the physics and
mathematics to prove your assertion. Where is it?

I have provided equations and references. Please
tell me exactly which ones you dispute so I can
quote them.

Although some people do occasionally attempt to correct you where you
have made a mistake ...

The only mistakes of which I have been accused
are poor choices of words to which I plead guilty.
Nobody has accused me of invalid equations.

What you are experiencing is the dumbing down of
technical people where the lumped circuit model
and "mashed potatoes" model of energy in a transmission
line has taken over.

The equation for standing waves has been quoted
from "Optics", by Hecht; "... Optics", by Born and
Wolf, "Fields and Waves ...", by Ramo and Whinnery,
"Antennas ...", by Kraus, and "Antenna Theory", by
Balanis.

I strongly suspect you are capable of understanding
those references.

The following two equations are equivalent and are
the equations for pure standing wave current as
exists as the primary current on standing wave
antennas.

I(x,t) = 2(V+/Z0)cos(kx)*cos(wt)

I(x,t) = (V+/Z0)[e^(jwt-kx) - e^(jwt-kx)]

If you cannot look at those equations and see that
the phase is unchanging relative to all points on
the wire, you need to go back to school and
hone your math skills.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

TEST

As a newcomer to the group I'm hesitant to join a discussion which has
been running for almost 200 postings, and where the protagonists
understand the topic in much greater depth than I do. But here
goes ....

My starting assumption is that EZNEC can model a helical inductor
reasonably accurately, with the exception of the increase in AC
resitance caused by proximity effects.

If I take an EZNEC model of a coil - 40 turns #14 wire, 6" diameter,
12" long - I discover it has a characteristic impedance of about 2550
ohms at a self-resonant frequency of around 6.1 MHz. If I use it as
the base loading coil for a short vertical antenna with a 6ft whip
above it, I notice that EZNEC shows a difference in the current at the
top of the coil compared with the bottom of about 0.69:1, and a
resonant frequency of 3.79MHz.

I then look to see which of the various models might reasonably
predict the values observed in the EZNEC modelling.

Clearly, a simple lumped-element inductor doesn't get close. I've read
various web pages and postings which argue qualitatively that things
like "distributed capacitance" might explain some of the observations,
but as yet I've seen no quantitative analysis which attempts to
predict the numbers.

In contrast, I look at the work of Corum & Corum and of G3YNH who
insist that "coils are best regarded as transmission lines", and I get
quantitative results which closely match the EZNEC results. For my
example coil, I get a self resonant frequency of 6.3MHz (cf 6.1MHz),
a characteristic impedance of 2792 ohms (cf 2550 ohms) and an Iout/Iin
ratio of 0.72 (cf 0.69)

Not only that, the transmission line model predicts an inductive
reactance very close to that needed for antenna resonance at 3.79 MHz

I'm a simple soul, and I don't pretend to understand all the maths
involved; I merely observe that the transmission line approach
delivers "hard numbers" that closely match those predicted by EZNEC.
I've yet to see another model get close. So, until I do, I guess I
have to favour the approach of Corum & Corum, G3YNH et al.

If someone can show me similarly accurate results from an approach
based on a lumped-element model, I'd be interested to see them.

Steve G3TXQ

Cecil Moore wrote:
Tom Donaly wrote:

No, it's not a diversion. You're making up things in your head.
The original controversy involved a claim by you that the coil in
a short, mobile antenna made up for the degrees lost in said
shortened antenna.

Sorry Tom, that is a false statement. Please stop misquoting
me.

I have the same recollection as Tom.

The loading coil occupies 19 degrees and the stinger
occupies 19 degrees. There is a 52 degree phase shift
at the coil to stinger junction. There are no "lost"
degrees. 19+52+19 = 90 degrees.

There were (are) two sides to the argument.

1. The coil furnishes the "lost" degrees.
FALSE!
The coil furnishes some number of degrees but not
nearly enough to make up for the phase shift at
the coil/stinger junction.

2. The coil supplies almost zero degrees.
FALSE!
The phase shift at the coil/stinger junction is not
enough to account for the "lost" degrees. The magnitude
of that phase shift is easily calculated on a Smith Chart.

Or, maybe

3. A less than quarter wave antenna is less than 90 degrees long.

ac6xg