Tom Donaly wrote:
Hecht forgot to put the phase difference in his formula.
It's no wonder there's no phase information in your
standing waves, Cecil, Hecht left it out.

You are mistaken. If Hecht left it out then so did Gene Fuller.
I suggest you listen to Gene when he says: Regarding the
cos(kz)*cos(wt) terms in the standing wave equation:

Gene Fuller, W4SZ wrote:
In a standing wave antenna problem, such as the one you describe, there is no
remaining phase information. Any specific phase characteristics of the traveling
waves died out when the startup transients died out.

Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again.

The only "phase" remaining is the cos (kz) term, which is really an amplitude
description, not a phase.

Not only
that, but where did he get the idea that it was sin(kx) instead
of cos(kx). I understand Hecht is a good old boy, but I'd like to
see his derivations.

Apparently, you are ignorant of the difference in conventions between
optics and RF engineering. In optics, there is no current so there is
no current changing phase at an open circuit. In optics, the M-field
changes directions but not phase. In RF engineering, a change in
direction of the H-field is considered to be a 180 degree phase shift.
Both conventions are correct as long as one understands them. Your
strange statement about Hecht above just proves your ignorance.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:
Tom Donaly wrote:

Hecht forgot to put the phase difference in his formula.
It's no wonder there's no phase information in your
standing waves, Cecil, Hecht left it out.


You are mistaken. If Hecht left it out then so did Gene Fuller.
I suggest you listen to Gene when he says: Regarding the
cos(kz)*cos(wt) terms in the standing wave equation:

Gene Fuller, W4SZ wrote:

In a standing wave antenna problem, such as the one you describe,
there is no remaining phase information. Any specific phase
characteristics of the traveling waves died out when the startup
transients died out.

Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen
again.

The only "phase" remaining is the cos (kz) term, which is really an
amplitude description, not a phase.


Not only
that, but where did he get the idea that it was sin(kx) instead
of cos(kx). I understand Hecht is a good old boy, but I'd like to
see his derivations.


Apparently, you are ignorant of the difference in conventions between
optics and RF engineering. In optics, there is no current so there is
no current changing phase at an open circuit. In optics, the M-field
changes directions but not phase. In RF engineering, a change in
direction of the H-field is considered to be a 180 degree phase shift.
Both conventions are correct as long as one understands them. Your
strange statement about Hecht above just proves your ignorance.

Whatever. I'd still like to see his derivations. In your case,
you're using the wrong equation anyway. What you really want is
Beta*l, or the radian length of your transmission line. You can
get that if you know, or can measure the usual parameters in the
transmission line impedance equation, using that equation to solve
for Beta*l. That won't prove your theory because you still haven't
shown that any one transmission line model is unique in terms of
substituting for your coil, but at least it'll give you something
to do.
73,
Tom Donaly, KA6RUH

Tom Donaly wrote:
Whatever. I'd still like to see his derivations.

"Optics", by Hecht, 4th edition, page 289.

The intensity of a light beam is associated with the E-field
so Hecht's equations are in relation to the E-field.

Speaking of the light standing wave: "The composite
disturbance is then:

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

Applying the indentity

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

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

Hecht says the standing wave "profile does not move through
space".

I have said the RF standing wave current profile does not move
through a wire.

Hecht says the standing wave phasor "doesn't rotate at all,
and the resultant wave it represents doesn't progress through
space - it's a standing wave."

I have said the same thing about the RF standing wave current
phasor.

Hecht says the standing wave transfers zero net energy. I have
said the same thing about RF standing waves.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:
Tom Donaly wrote:

Whatever. I'd still like to see his derivations.


"Optics", by Hecht, 4th edition, page 289.

The intensity of a light beam is associated with the E-field
so Hecht's equations are in relation to the E-field.

Speaking of the light standing wave: "The composite
disturbance is then:

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

Applying the indentity

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

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

Hecht says the standing wave "profile does not move through
space".

I have said the RF standing wave current profile does not move
through a wire.

Hecht says the standing wave phasor "doesn't rotate at all,
and the resultant wave it represents doesn't progress through
space - it's a standing wave."

I have said the same thing about the RF standing wave current
phasor.

Hecht says the standing wave transfers zero net energy. I have
said the same thing about RF standing waves.

If it's a solution to the wave equation it's o.k., Cecil, but
Hecht is still not using the case where there is a phase difference
between the two waves. If it isn't in the original equation it
won't be in the final version since they're just two ways of
saying the same thing. That's fine because it's the wrong
equation anyway for what you want, which involves impedances
and length, which you probably don't want to deal with because
you're probably under the impression they're just virtual and
not real, and so not worthy of inclusion in your theory.
73,
Tom Donaly, KA6RUH

Tom Donaly wrote:
If it's a solution to the wave equation it's o.k., Cecil, but
Hecht is still not using the case where there is a phase difference
between the two waves.

Yes, he is, Tom. The phase *disappears* when you add the two
traveling waves. That you don't recognize that fact of physics
is the source of your misconception. The forward and reflected
wave phasors are rotating in opposite directions at the same
angular velocity. That makes their sum a constant phase value
for half the cycle and the opposite constant phase value for
the other half of the cycle.

I and Richard Harrison have already explained that a number of
times quoting Kraus and Terman.

Here are a number of problems. I(f) is forward current and
I(r) is reflected current. Please everybody, perform the
following phasor additions where I(f)+I(r) is the *standing
wave current*:

I(f) I(r) I(f)+I(r)

1 amp at 0 deg 1 amp at 0 deg _________________

1 amp at -30 deg 1 amp at +30 deg _________________

1 amp at -60 deg 1 amp at +60 deg _________________

1 amp at -90 deg 1 amp at +90 deg _________________

1 amp at -120 deg 1 amp at +120 deg _________________

1 amp at -150 deg 1 amp at +150 deg _________________

1 amp at -180 deg 1 amp at +180 deg _________________

If you guys will take pen to paper and fill in those blanks
you will uncover the misconception that has haunted this
newsgroup for many weeks. If you need help with the math,
feel free to ask for help.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:
(snip)
Here are a number of problems. I(f) is forward current and
I(r) is reflected current. Please everybody, perform the
following phasor additions where I(f)+I(r) is the *standing
wave current*:

I(f) I(r) I(f)+I(r)

1 amp at 0 deg 1 amp at 0 deg 2 A @ 0 deg

1 amp at -30 deg 1 amp at +30 deg 1.72 A @ 0 deg

1 amp at -60 deg 1 amp at +60 deg 1 A @ 0 deg

1 amp at -90 deg 1 amp at +90 deg 0 A @ 0 deg

1 amp at -120 deg 1 amp at +120 deg 1 A @ 180 deg

1 amp at -150 deg 1 amp at +150 deg 1.72 A @ 180 deg

1 amp at -180 deg 1 amp at +180 deg 2 A @ 180 deg

If you guys will take pen to paper and fill in those blanks
you will uncover the misconception that has haunted this
newsgroup for many weeks. If you need help with the math,
feel free to ask for help.

What misconception? That all current in a standing wave has the same
phase, rather than one of two possible phases?

John Popelish wrote:
What misconception? That all current in a standing wave has the same
phase, rather than one of two possible phases?

The misconception is not yours, John. W7EL used that current to
try to measure the phase shift through a coil and so did W8JI
who came up with an unbelievable 3 nS.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:

Tom Donaly wrote:

If it's a solution to the wave equation it's o.k., Cecil, but
Hecht is still not using the case where there is a phase difference
between the two waves.


Yes, he is, Tom. The phase *disappears* when you add the two
traveling waves. That you don't recognize that fact of physics
is the source of your misconception. The forward and reflected
wave phasors are rotating in opposite directions at the same
angular velocity. That makes their sum a constant phase value
for half the cycle and the opposite constant phase value for
the other half of the cycle.

I and Richard Harrison have already explained that a number of
times quoting Kraus and Terman.

Here are a number of problems. I(f) is forward current and
I(r) is reflected current. Please everybody, perform the
following phasor additions where I(f)+I(r) is the *standing
wave current*:

I(f) I(r) I(f)+I(r)

1 amp at 0 deg 1 amp at 0 deg _________________

1 amp at -30 deg 1 amp at +30 deg _________________

1 amp at -60 deg 1 amp at +60 deg _________________

1 amp at -90 deg 1 amp at +90 deg _________________

1 amp at -120 deg 1 amp at +120 deg _________________

1 amp at -150 deg 1 amp at +150 deg _________________

1 amp at -180 deg 1 amp at +180 deg _________________

If you guys will take pen to paper and fill in those blanks
you will uncover the misconception that has haunted this
newsgroup for many weeks. If you need help with the math,
feel free to ask for help.

Cecil, if you don't put any phase information in your
original formula it won't be there when you say the
same thing some other way. But if you
do put it in there, then it has to affect both formulas.
If it disappears, you've done something wrong. If you and
Harrison can't figure out how to extract phase information
from a standing wave you should return your diplomas to
wherever you got them from.
73,
Tom Donaly, KA6RUH
(P.S. Let me give you a hint: first you have to find
out what phase means in a standing wave on a transmission
line. You probably already think you know, though, so I
don't expect you to bother much about it.)

Tom Donaly wrote:
If it disappears, you've done something wrong.

There is no phase information in standing wave phase, Tom.
I can't find it, Gene fuller can't find it, Eugene Hecht
can't find it, and James Clerk Maxwell can't find it.

Any and all phase information in the standing wave phase
disappears during superposing.

Let me give you another example. Assume that we superpose
one amp of DC current flowing in one direction and one
amp of DC current flowing in the other direction. What
does the superposed amplitude tell us about the amplitudes
of the superposed currents? Nothing, except they were
equal.
--
73, Cecil http://www.qsl.net/w5dxp

Tom Donaly, KA6RUH wrote:
""---first you have to find out what phase means in a standing wave
transmission line."

Cecil knows very well what phase means in a transmission line. Terman
describes it best for me, but it would be best to have his book with all
his diagrams which makes his explanation of how standing waves are
established simple indeed.

Terman writes on page 89 of his 1955 edition:
"Transmission line with Open-Circuited Load."
(This is related to the standing-wave antenna which also ends up with an
open-circuit load.)
"When the load impedance is infinite, Eq.(4-14)
(This gives the reflection coefficient rho as the vector ratio of the
reflected wave to the incident wave at the load) shows that the
coefficient of reflecftion will be 1 on an angle of zero. Under these
conditions the incident and reflected waves (voltages) will have the
same phase. As a result, the voltages of the two waves add
arithmetically so that at the load E1 = E2 = EL/2. (Voltage doubles at
the open circuit.)

Under these conditions it follows from Eqs. (4-8)
(Eforward/Iforward=Zo) and (4-11)
(Ereflected / Ireflected=-Zo) that the currents of the two waves are
equal in magnitude but opposite in phase; they thus add up to zero load
current, as must be the case if the load is open-circuited.

Consider now how these two waves behave as the distance l from the load
increases. The incident wave advances in phase beta radians per unit
length, while the reflected wave lags correspondingly; at the same time
magnitudes do not change greatly when the attenuation-constant alpha is
small. The vector sum of the voltages of the two waves is less than the
arithmetic sum, as illustrated in Fig. 4-3a, for l=lambda/8. This
tendency continues until the distance to the load becomes exactly a
quarter wavelength, i.e.,until beta l = pi/2. The incident wave has then
advanced 90-degrees from its phase position at the load, while the
reflected wave has dropped back a similar amount. The line voltage at
this point is thus the arithmertic difference of the voltages of the two
waves, as shown in Fig. 4-3a, for l=lambda/4 and it will be quite small
if the attenuation is small. The resultant voltage will not be zero,
however, because some attenuation will always be present, and this
causes the incident wave to be larger and the reflected wave to be
smaller at the quarter-wave length point than at the load, where the
amplitudes are exactly the same."

This is enough of Terman`s desctiption to establish the pattern of SWR.
He describes simply but not too simply. Almost anything anyone would
want to know is in the book. The illustrations are worth thousands of
words.
Anytime I have any doubt about radio, Terman can straighten me out.

Best regards, Richard Harrison, KB5WZI