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

Cecil Moore wrote:
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.

Your idea of phase is to compare amplitudes at two separate
places on the same wave and noting the time difference in
behavior. You're right, you get the same "phase" if you
do that to a standing wave in a lossles medium. You're not
right, however, in thinking that the phase difference between
two waves travelling in different directions down a transmission
line can never be known. But as I wrote before, that isn't what
you should be after. You should want to know the Beta*l of
the coil on your antenna so you'll know its electrical length.
And you can know it if it is true that you can model a coil
as a simple transmission line. That's a big if, but it's something
you should have thought of before you shot off your mouth.
73,
Tom Donaly, KA6RUH

Tom Donaly wrote:
You should want to know the Beta*l of
the coil on your antenna so you'll know its electrical length.

The discussion is no longer about coils. It's clear that a
lot of posters don't understand the nature of standing waves.
If they don't understand standing waves in a transmission
line or on a wire, they cannot possibly understand standing
waves on a coil.
--
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

Cecil Moore wrote:
Tom Donaly wrote:

You should want to know the Beta*l of
the coil on your antenna so you'll know its electrical length.


The discussion is no longer about coils. It's clear that a
lot of posters don't understand the nature of standing waves.
If they don't understand standing waves in a transmission
line or on a wire, they cannot possibly understand standing
waves on a coil.

Well, Cecil, you've certainly shown your knowledge is weak in
this area. You can improve the general knowledge by being the
first to crack the books.
73,
Tom Donaly, KA6RUH

Tom Donaly wrote:

Cecil Moore wrote:
The discussion is no longer about coils. It's clear that a
lot of posters don't understand the nature of standing waves.
If they don't understand standing waves in a transmission
line or on a wire, they cannot possibly understand standing
waves on a coil.

Well, Cecil, you've certainly shown your knowledge is weak in
this area. You can improve the general knowledge by being the
first to crack the books.

The nature of standing waves is not a difficult subject. Some
people have a single particular misconception about standing
waves that have lead them to technically incorrect conclusions
about standing wave antennas. In fact, before I brought up the
subject, it appeared they didn't even realize that a mobile
antenna is a standing wave antenna.

Given a lossless, unterminated transmission line, with two black
boxes located at points along the line.

Source-----------a-BBox-b-------------c-BBox-d-----------open

The current at 'a' is one amp and the current at 'b' is zero

The current at 'c' is zero and the current at 'd' is one amp

What's in the black boxes?
--
73, Cecil http://www.qsl.net/w5dxp