Roy Lewallen wrote:
Absolutely true. Cecil complains that people won't engage in a technical
discussion with him. Many have tried, and all we get in response is
evasion, misquotes, diversion, and brushing off of any evidence contrary
to his preconceived notions.

Roy, I'll tell you the same thing I told W8JI. It's time to stop
the ad hominem attacks and discuss the technical issues.

You tried to use standing wave current, containing no phase, to
measure the delay through a coil. You have said previously that
standing wave current flows just like traveling wave current.
You said that in spite of what Hecht says in "Optics".

Hecht had to say in "Optics":

"E(x,t) = 2*Eo*sin(kx)*cos(wt) This is the equation for a STANDING
or STATIONARY WAVE, as opposed to a traveling wave. Its profile does
not move through space; it is clearly not of the form Func(x +/- vt).
.... [Standing wave phase] doesn't rotate at all, and the resultant
wave it represents doesn't progress through space - its a standing
wave."

If standing wave light doesn't move through space, then standing wave
RF doesn't move through a wire. Do you disagree with Hecht?
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:
(snip)
Compared to zero amps of standing wave current when the forward current
phasor and the reflected current phasor are 180 degrees out of phase,
just how much effect can capacitance have?

A standing wave voltage passes exactly as much (AC RMS) current
through a capacitance as a traveling wave voltage does. If there is
voltage at the ends of the coil, then there is capacitive current
driven by those voltages, regardless of whether the voltage is from a
single traveling wave or the superposition of two of them.

Cecil wrote, "It's time to stop
the ad hominem attacks and discuss the technical issues."

Ready when you are, lad. Suggest you start by establishing just how it
is that an antenna wire supports waves. Gauss's theorem and Faraday's
law may come in handy. Please don't spare anything.

The reason you need to do this for me to even begin to believe you have
any idea what you are talking about is that you have rejected out of
hand some very fundamental concepts that I've put numbers on for you.
You ask for something, and then you reject the answer but give no valid
reason why. I've tried to give you a way to SUPPORT what you are
saying, and you can't even recognize that, apparently.

Now YOU go back to the real fundamentals and give it to us straight,
with full math treatment. Until you do, as far as I'm concerned, you
don't have a leg to stand on. If you can do a credible job starting
with Maxwell's equations, I might begin to believe you have some
understanding of the subject. And I don't want it parroted from
someone else's writing, I want it done from the ground up by you.

If you have some trouble doing that with an antenna wire, just try it
with an ideal coaxial TEM line. It's easy there; I've done it out of
idle curiosity one evening, and it was quite enlightening to see how
nicely it all agreed with what I already knew about propagation along a
line.

Lay it on us, Cecil. Start with the fundamentals. And don't be
dragging out that tired old travelling-waves/standing-waves stuff till
you've established that you actually can even have waves, and just what
it is that governs their behaviour.

Cheers,
Tom

John Popelish wrote:
Cecil Moore wrote:
Compared to zero amps of standing wave current when the forward current
phasor and the reflected current phasor are 180 degrees out of phase,
just how much effect can capacitance have?

A standing wave voltage passes exactly as much (AC RMS) current through
a capacitance as a traveling wave voltage does.

But the two waves are different as can be seen from their
equations. A traveling wave transfers net energy along a
transmission line or antenna wire. A standing wave transfers
zero net energy along a transmission line or antenna wire.

From "Fields and Waves in Modern Radio", by Ramo & Whinnery,
2nd edition, page 43: "The total energy in any length of line
a multiple of a quarterwavelength long is constant, merely
interchanging between energy in the electric field of the
voltages and energy in the magnetic field of the currents."

Hecht says it best in "Optics" concerning standing waves:

"The composite disturbance is then:

E = Eo[sin(kx+wt) + sin(kx-wt)]

Applying the identity:

sin A + sin B = 2 sin 1/2(A+B)*cos 1/2(A-B)

yields:

E(x,t) = 2*Eo*sin(kx)*cos(wt)"

"This is the equation for a STANDING or STATIONARY WAVE, as opposed
to a traveling wave. Its profile does not move through space; it is
clearly not of the form Func(x +/- vt)."

[Standing wave phase] "doesn't rotate at all, and the resultant
wave it represents doesn't progress through space - its a standing
wave."

Speaking of "... net transfer of energy, for the pure standing
wave there is none."
--
73, Cecil http://www.qsl.net/w5dxp

K7ITM wrote:
The reason you need to do this for me to even begin to believe you have
any idea what you are talking about is that you have rejected out of
hand some very fundamental concepts that I've put numbers on for you.

I've rejected your obvious attempts at logical diversions.

Lay it on us, Cecil. Start with the fundamentals. And don't be
dragging out that tired old travelling-waves/standing-waves stuff till
you've established that you actually can even have waves, and just what
it is that governs their behaviour.

:-) Just one more attempt at a logical diversion.

I think we can all assume that EM waves exist and are
capable of propagating along a transmission line, or
antenna wire, or even in free space, e.g. light.

What we cannot assume is that standing waves move
or progress through space (or wire). Eugene Hecht
says they don't.
--
73, Cecil http://www.qsl.net/w5dxp

but we can not
use electrical degrees to 'splain the behavior of coiled antenna wire?

I can see how problems could arise going by the length of coil
wire length in degrees only. Lets say you run a coil 1 foot from the
base. Lets say that coil uses 25 turns to tune a particular frequency.
Now, move the coil up 2 ft higher, and see if that same 25 turns will
tune the same frequency. It won't. You will have to add a few more
turns.
So just going by the total mast plus coil wire length in degrees could
vary
all over the map just by changing the position of the coil. As you
raise
the coil, you will have to add more and more of "degrees" of wire to
tune the same frequency. :/
Dunno...There may well be some variation of current from the bottom
vs the top of the coil, but overall, I still view the operation of a
loading
coil as a "lumped" mechanism overall.
Even if you all decide that the current changes, or it doesn't , it
ain't
gonna make a hoot's worth of difference in the design of mobile whips.
I think it's an argument that has no real value to me as far as mobile
whips go. The performance of all the various coil heights, and configs
have been well known for years. Coil current taper or not.
I just don't see the facination with arguing about something that even
if
decided one way or the other, still won't make any difference in the
final
antenna design. Oh well...Continue the tail chasing excercise....
I'm outa this one... One post is all I will waste on this subject..
I couldn't mount my coil much higher if I wanted to... Current taper or
not. :/
MK

Cecil Moore wrote:

John Popelish wrote:

Cecil Moore wrote:

Compared to zero amps of standing wave current when the forward current
phasor and the reflected current phasor are 180 degrees out of phase,
just how much effect can capacitance have?


A standing wave voltage passes exactly as much (AC RMS) current
through a capacitance as a traveling wave voltage does.


But the two waves are different as can be seen from their
equations. A traveling wave transfers net energy along a
transmission line or antenna wire. A standing wave transfers
zero net energy along a transmission line or antenna wire.

From "Fields and Waves in Modern Radio", by Ramo & Whinnery,
2nd edition, page 43: "The total energy in any length of line
a multiple of a quarterwavelength long is constant, merely
interchanging between energy in the electric field of the
voltages and energy in the magnetic field of the currents."

Hecht says it best in "Optics" concerning standing waves:

"The composite disturbance is then:

E = Eo[sin(kx+wt) + sin(kx-wt)]

Applying the identity:

sin A + sin B = 2 sin 1/2(A+B)*cos 1/2(A-B)

yields:

E(x,t) = 2*Eo*sin(kx)*cos(wt)"

"This is the equation for a STANDING or STATIONARY WAVE, as opposed
to a traveling wave. Its profile does not move through space; it is
clearly not of the form Func(x +/- vt)."

[Standing wave phase] "doesn't rotate at all, and the resultant
wave it represents doesn't progress through space - its a standing
wave."

Speaking of "... net transfer of energy, for the pure standing
wave there is none."

Cecil, how can you quote Hecht when you don't have the foggiest notion
what he's talking about?
Here's a more general equation for you Cecil:
(A1-A2)*Cos(wt-kx) + 2*A2*Cos(kx+d/2)*Cos(wt+d/2). Do you have
any idea what it should represent? Does it satisfy the wave equation?
Does it represent anything real? Sit and think about it before you
get hysterical.
73,
Tom Donaly, KA6RUH

Cecil Moore wrote:
Time to stop the ad hominem attacks and address this technical issue.
--
73, Cecil http://www.qsl.net/w5dxp

I'm glad to hear that.

When you show a track record of being honest and you stop those attacks
and your constant distortions of what other people say, I'm sure people
will start talking to you again.

73 Tom

wrote:
I just don't see the facination with arguing about something that even
if
decided one way or the other, still won't make any difference in the
final
antenna design.

The sun still rises every morning whether it is caused by
the earth's rotation or by the Sun God riding his chariot
across the sky. The facination is called technical correctness.
--
73, Cecil http://www.qsl.net/w5dxp

"Richard Harrison" wrote:
It is the convention to describe AM broadcast towers in electrical
degrees. Harold Ennes reprints an RCA resistance chart for heights
between 50 and 200 degrees in "AM-FM Broadcast Maintenance".

Formula given is:
Height in electrical degrees = Height in feet X frequency in kc X
1.016 X 10 to the minus 6 power.
_______________

If electrical length is defined as the physical condition where feedpoint
reactance is zero (e.g., resonance), then the true electrical length of an
AM broadcast radiator on a given frequency is a function of the physical
length AND physical width of that radiator. This was proven experimentally,
and documented by George Brown of RCA Labs in his paper "Experimentally
Determined Impedance Characteristics of Cylindrical Antennas" published in
the Proceedings of the I.R.E. in April, 1945. It also has been proven in
thousands of independent measurements of AM broadcast radiators ever since.

The curves in Figure 3 of Brown's paper show the feedpoint reactance terms
of the base impedance of an unloaded monopole of various lengths and widths,
working against a nearly perfect ground plane. Those values cross the zero
reactance axis at physical heights ranging from about 80 degrees (for the
widest radiator) to about 86 degrees for the most narrow.

Brown calculated height in degrees as (Physical Height in feet x Frequency
in kHz ) / 2725 . Brown's equation, the one in the Harold Ennes quote
above, and the one that the FCC uses in their published data all define only
the relationship of the physical length of the radiator to its free-space
wavelength in degrees at that frequency.

But clearly these lengths in degrees do not define the self-resonant length
of that radiator. The self-resonant length, invariably, will be shorter by
several percent. This fact is easily confirmed by simple NEC models, for
those who want to probe into George Brown's data.

Tables relating a single value of base impedance as typical for towers of
various electrical heights (only) must be read with an understanding of the
above realities. For example, Ennes' list shows a tower of 90 electrical
degrees to have zero reactance. But Brown's 1945 paper and a great amount
of later field experience shows that this is incorrect, for the conventional
use of this term.

RF