Cecil Moore wrote:

Jim Kelley wrote:
Yikes, Cecil. Using that logic, you're basically arguing that every 1/2
WL or 180 degrees, a forward wave turns into a reflected wave.

Nope, but half the time in a horizontal standing wave antenna, the
forward current is flowing toward the left while the reflected current
is flowing toward the right, and vice versa. That's simply a characteristic
of RF current.

The point is it's not a reversal in phase, abrupt or otherwise. A
reversal in polarity, maybe. And you can't try to argue that polarity
and phase mean the same thing. This is really common knowledge,
freshman level stuff, Cecil. You really ought to just let it drop.
It's not even pertinent to the topic. But since for you, arguing is an
objective in itself, I'm sure you'll continue to argue about it.

73, Jim AC6XG

Jim Kelley wrote:

Cecil Moore wrote:
Nope, but half the time in a horizontal standing wave antenna, the
forward current is flowing toward the left while the reflected current
is flowing toward the right, and vice versa. That's simply a characteristic
of RF current.

The point is it's not a reversal in phase, abrupt or otherwise. A
reversal in polarity, maybe. And you can't try to argue that polarity
and phase mean the same thing.

There are only two directions possible for real current in a wire so
real polarity and real phase indeed do mean the same thing. Kraus clearly
agrees. Take a look at Figure 14-4 on page 465 of _Antennas_For_All_Applications_,
third edition. The graph of the current phase is a square wave that jumps
from zero degrees to 180 degrees and back. Between you and Kraus, I choose Kraus.

A wire is one-dimensional with two and only two directions. In what dimension
do the extra phases of the current that you allude to exist? The real part of
I*e^jwt is either positive or negative, i.e. binary. The only possible change
of direction is abrupt. The change in magnitude is not abrupt, but the change
in phase is abrupt, just as Kraus says.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote:
There are only two directions possible for real current in a wire so
real polarity and real phase indeed do mean the same thing.

Non-sequitur, ad absurdum, ad nausium.

Thank you.

73 de jk

Jim Kelley wrote:
Cecil Moore wrote:
There are only two directions possible for real current in a wire so
real polarity and real phase indeed do mean the same thing.

Non-sequitur, ad absurdum, ad nausium.

So that's your opinion of Kraus? In that freshman class you mentioned
they must have taught you that math models dictate reality. Have you
been a case of arrested development ever since? Don't you realize that,
in a one-dimensional environment, the 'j' operator is really imaginary?
There is no dimension in which j1.0 can actually exist in reality.

The current in a wire at a certain point and time is 0 + j1.0.
Among the electron charge carriers at that point, exactly where
does that j1.0 exist? The physical wire is essentially a one
dimensional environment for those free electrons. In one dimension,
polarity and phase are the same thing. For the current on a standing
wave antenna, Kraus clearly indicates there are only two phase
possibilities, zero and 180 degrees. Maybe you should contact Kraus
and tell him that he is wrong.
--
73, Cecil, W5DXP

Jim Kelley wrote:
Non-sequitur, ad absurdum, ad nausium.

I'm going to let you do the math to convince yourself
that Kraus is correct, given his assumptions about thin
wire antennas.

Assume two traveling-wave currents, each with a maximum
magnitude of 1.0 amps, and flowing in opposite directions.
They are a forward current wave and a reflected current wave,
If and Ir. This will set up a classical current standing wave.
Here are five possible superpositions of those two currents.
('+' is the 0,0 origin)

(1)*********************************************** **************

+------- 1.0 +-------
If = 1.0 at zero degrees Ir = 1.0 at zero degrees

What is the phase of the sum of those two phasors? __________

(2)*********************************************** **************

/ +
/ \
/ \
+ \
If = 1.0 at 45 degrees Ir = 1.0 at -45 degrees

What is the phase of the sum of those two phasors? __________

(3)*********************************************** **************

| +
| |
| |
| |
+ |
If = 1.0 at 90 degrees Ir = 1.0 at -90 degrees

What is the phase of the sum of those two phasors? __________

(4)*********************************************** **************

\ +
\ /
\ /
\ /
+ /
If = 1.0 at 135 degrees Ir = 1.0 at -135 degrees

What is the phase of the sum of those two phasors? __________

(5)*********************************************** **************

-------+ -------+
If = 1.0 at 180 degrees Ir = 1.0 at -180 degrees

What is the phase of the sum of those two phasors? ___________

************************************************** ************

When you guys figure it out, you will realize why Kraus shows only
two possible phases for current in standing wave antennas, zero
degrees and 180 degrees. Everyone who doubts the binary nature of
the phase of standing waves, please post your answers.
--
73, Cecil, W5DXP

Cecil, W5DXP wrote:
"Take a look at Figure 14-4 on page 465 of "Antennas For All
Applications---third edition."

Yes. If you don`t have a copy, you are truly deprived.

Kraus corroborates the square phase diagram in the text. On page 463, he
says: For each length the relative amplitude and phase of the current
are presented for omega prime = 10 and omega prime = infinity
corresponding to total length-diameter ratios (l/a) of 75 and infinity"
(a very thin wire).

What Kraus shows is a center-fed 5/4-wave dipole, 5/8-wave per side, for
maximum gain without production of significant extra lobes.

At 1/2-wave back from the open circuit ends of the dipole, phase moves
up a vertical line from the zero-degree level to the 180-degree level.
This is in the case of the extremely thin wire. For the l/a=75 wire, the
phase change is much more gradual.

Please look at Terman`s Fig. 4-5 on page 94 of his 1955 edition of
"Electronic and Radio Engineering".

Fig. 4-5 is: "Phase relations on a transmission line for two typical
conditions. In these curves, the voltage of the incident wave at the
load is used as the reference phase, and the line attenuation is assumed
to be small."

For the case of the complete reflection, the load is an open circuit as
shown. The reflection coefficient is 1 (one) on an angle of zero. The
reflected wave will be just as strong as the incident wave. The
reflection causes the voltages of incident and reflected waves to have
the same phase at an open circuit. They add arithmetically, and the
total voltage across the open circuit (load) end of the line doubles. In
this case the current of the two waves are equal and of opposite phase
at the open circuit. Thus they add to zero at this point.

At a distance of 1/4-wave back from the open circuit, the incident wave
has advanced by 90-degrees from its phase position at the load, while
the reflected wave has dropped back by the same 90-degrees. The line
voltage from the forward (incident) and reflected waves at this point,
one quarterwave back from the open circuit, are now 180-degrees
out-of-phase. Their sum is nearly zero from a complete reflection on a
nearly lossless line. The currents from the forward and reflected waves
which were out-of-phase at the open circuit are now in-phase, at this
point, 1/4-wave back from the open circuit.

FROM Fig. 4-5(c), the phase line representing the case of a complete
reflection, goes from zero-degrees for the voltages at the open circuit,
and abruptly falls to a 90-degree lead with respect to the incident
voltage at the open-circuit (load).

AT 1/4-wave back from the load, the phase shifts instantly from
90-degrees lead to 90-degrees lag.

At 1/2-wave back from the load, the phase shifts instantly from
90-degrees lag to 90-degrees lead. This flip-flop behavior continues
each 1/4-wave of travel back from the reflection point.

For the case shown for the reflection coefficient of 0.4, the phase
oscillates between leads and lags of 40-degrees, not the 90-degree
limits of the complete reflection case.

The phase reversals in Kraus` Figure 14-4 are analogous to those in
Terman`s figs. 4-5 and 4-7. All show abrupt 180-degree phase shifts
alternating at regular intervals.

Best regards, Richard Harrison, KB5WZI