On May 24, 3:06*pm, lu6etj wrote:
For example this part = "by inserting a pad having 15 to 20 dB
I give the following example: If we load a generator directly with a
resistance of 10 ohms, without any transmission line, there are not
traveling waves interfering, therefore there are not stationary waves,

Yes, standing waves are hard to visualize, but there is indeed same-
cycle interference involving forward waves and reflected waves. There
is a certain delay from the source signal to the load and back that
can be calculated if one chooses. The wave reflection model is closer
to Maxwell's equations than is the lumped-circuit model where EM waves
propagate instantaneously. Maybe the concepts presented in the
following paper would help. There is no transmission line for a Tesla
coil but reflection effects still exist. The lumped circuit model, to
which you allude, incorrectly assumes that signals can travel at
faster than the speed of light, an obvious impossibility.

http://www.ttr.com/corum/index.htm

Incidentally, this is the reason that W8JI measured a 3 ns delay
through a foot-long 75m loading coil. There were same-cycle
reflections existing in a near-infinite SWR situation. In such a
configuration, the phase of the current doesn't change at all yet W8JI
assumed the measured phase change was proportional to the delay
through the coil. Nothing could be farther from the technical truth.
--
73, Cecil, w5dxp.com

On 24 mayo, 21:30, Cecil Moore wrote:
On May 24, 3:06*pm, lu6etj wrote:

For example this part = "by inserting a pad having 15 to 20 dB
I give the following example: If we load a generator directly with a
resistance of 10 ohms, without any transmission line, there are not
traveling waves interfering, therefore there are not stationary waves,

Yes, standing waves are hard to visualize, but there is indeed same-
cycle interference involving forward waves and reflected waves. There
is a certain delay from the source signal to the load and back that
can be calculated if one chooses. The wave reflection model is closer
to Maxwell's equations than is the lumped-circuit model where EM waves
propagate instantaneously. Maybe the concepts presented in the
following paper would help. There is no transmission line for a Tesla
coil but reflection effects still exist. The lumped circuit model, to
which you allude, incorrectly assumes that signals can travel at
faster than the speed of light, an obvious impossibility.

http://www.ttr.com/corum/index.htm

Incidentally, this is the reason that W8JI measured a 3 ns delay
through a foot-long 75m loading coil. There were same-cycle
reflections existing in a near-infinite SWR situation. In such a
configuration, the phase of the current doesn't change at all yet W8JI
assumed the measured phase change was proportional to the delay
through the coil. Nothing could be farther from the technical truth.
--
73, Cecil, w5dxp.com


Hi Cecil. thank you very much for your answer. (I am a "fan" of your
rationale and very practical multiband open wire antenna feeding and I
do not know why it is no so popular as G5RV in my country).
.....
I know a model is necessary false by definition because is only a
model (an approximation to the hipothetical "real thing"), but I do
not imagine what is the tranmission line in the source-load
combination of my idealized model circuit example. I am not capable to
judge validity of idealized circuit theory in general to this example,
neither. Please, could you tell me which would be the transmission
line Zo in my resistive divider example?

Anyway, my question is about validity of the assertion that reflected
wave -in that example- IS ABSORBED by the pad. According to my simple
calculations this hipothesis, as I see it, it does not coincide with
my early learnings.

For example, with a 2 V generator with Zs=1 ohm, Zc=4 ohms and Zo=1
ohm, Pc is 0.64 W. Then Pf =1 W (as Owen says in his article), Pr=0.36
W. Rendering Ef=1 V, and Vf=0.6V. Summing both in phase gives 1,6 V on
the line-in point (same as on load point).
These are the same power and voltages values that simple resistive
divider predicts. The system fulfills the Kirchoff law and all power
(as we learn in circuits theory) it flows from source to load.
In the example I suggest a half wave transmission line loaded with 4
ohms it is at practical effects indistinguishable from a 4 ohms
resistive load directly connected to generator. What would be the
reflected power that would be dissipating in Zs (or the pad)?

This is not opposed to the conjugate mirror principle explained,
neither other propositions given in the cited article. IMHO reflected
power never "returns into" generators when they are active (and in
steady state); reflected power it is re-reflected in conjugated match,
and vectorially composed to render a load impedance to the generator
when this is directly connected to the line (when there is not any
matching devices inserted).
I do not suggesting that reflected power is "virtual" or any similar
thing, of course if we insert a circulator to separate both powers,
generator now would see 1 ohm load, could develope 1 W incident, 0 W
reflected (Pn=1W) on circulator input, 0.36 W would be outputting on
the other port to render 0.64 W (Pn) to the load with 1 W Pf and 0,36
W Pr again.

If I am in error please give me your explanations.

73

Miguel ghezzi LU6ETJ

On May 24, 10:31*pm, lu6etj wrote:
Anyway, my question is about validity of the assertion that reflected
wave -in that example- IS ABSORBED by the pad. According to my simple
calculations this hipothesis, as I see it, it does not coincide with
my early learnings.

Miguel, let's switch your example over to an easier to understand
example. Assume an ideal signal generator equipped with a resistive
circulator load. Let's call such a device an SGCR, a Signal Generator
equipped with a Circulator and a Resistor. Assume that 100% of the
reflected energy is dissipated in the circulator load resistor (none
re-reflected) and none of the reflected energy reaches the source. So
here is the block diagram.

SGCR--------feedline--------load

That model should be easier to discuss than the pad attenuator model.
What do you think?
--
73, Cecil, w5dxp.com

On 25 mayo, 11:49, Cecil Moore wrote:
On May 24, 10:31*pm, lu6etj wrote:

Anyway, my question is about validity of the assertion that reflected
wave -in that example- IS ABSORBED by the pad. According to my simple
calculations this hipothesis, as I see it, it does not coincide with
my early learnings.

Miguel, let's switch your example over to an easier to understand
example. Assume an ideal signal generator equipped with a resistive
circulator load. Let's call such a device an SGCR, a Signal Generator
equipped with a Circulator and a Resistor. Assume that 100% of the
reflected energy is dissipated in the circulator load resistor (none
re-reflected) and none of the reflected energy reaches the source. So
here is the block diagram.

SGCR--------feedline--------load

That model should be easier to discuss than the pad attenuator model.
What do you think?
--
73, Cecil, w5dxp.com

Excuse me Cecil:

I am reading this newsgroup through Google groups web page and I just
realized that later replies to previous post are intercalated in the
thread, while I expected to see it always at the end of it, for that
reason I did not ACK before to it. (I hope yours be the only one, I
will review all thread tho chek for others).

In a early post I wrote = "of course if we insert a circulator to
separate both powers, generator now would see 1 ohm load, could
develope 1 W incident, 0 W reflected (Pn=1W) on circulator input, 0.36
W would be outputting on the other port to render 0.64 W (Pn) to the
load with 1 W Pf and 0,36 W Pr again"
Is this result OK for you?.

The thread advance toward more deeper issues since :), and now I have
been analizing all the matter because it quickly superceed my original
doubt. A few minutes ago had started to read your article (http://
www.w5dxp.com/energy.htm) and the Roy's one (http://eznec.com/misc/
Food_for_thought.pdf) and yesterday I have been reloading my old
"Transmission lines antennas and wave guides" from King, Mimno & Wing
to review the issue from that classical perspective.

I am interested in your optic analogy, I can imagine the load as a
partially reflecting surface, real part of it as absorbance
(transmittance if it was a radiator). line as a unidimensional medium
and reflection as the form of "redistribute energy" (is it OK?) and a
coherent light source for the voltage source, but I am still trying to
visualze the optical equivalent of source resistance and its job to be
a good analog, Also I am interested in check other values and
conditions in your other article (first part) with 45 degree line.

Thank you very much for your helping and inspiration.

73 - Miguel LU6ETJ

On May 27, 9:50*am, lu6etj wrote:
I am reading this newsgroup through Google groups web page and I just
realized that later replies to previous post are intercalated in the
thread, while I expected to see it always at the end of it, for that
reason I did not ACK before to it. (I hope yours be the only one, I
will review all thread tho chek for others).

I am also using Google since ATT dropped Usenet. I liked Thunderbird a
lot better than Google's usenet interface but I am adapting. The above
information is good to know. Thunderbird has a way to keep up with
unread vs read postings but Google doesn't seem to - at least I don't
know how to do it on Google.

In a early post I wrote = "of course if we insert a circulator to
separate both powers, generator now would see 1 ohm load, could
develope 1 W incident, 0 W reflected (Pn=1W) on circulator input, 0.36
W would be outputting on the other port to render 0.64 W (Pn) to the
load with 1 W Pf and 0,36 W Pr again"
Is this result OK for you?.

The SGCR source is usually designed for 50 ohms, i.e. the signal
generator always "sees" a 50 ohm load because it does not "see" any
reflected energy. The ideal circulator is usually designed with 50 ohm
line and a 50 ohm load resistor. If we could stick with that
particular configuration for the SGCR source, it would aid in my
understanding what is the actual system configuration, i.e. not your
fault but I am confused by your above posting.

I am interested in your optic analogy, I can imagine the load as a
partially reflecting surface, real part of it as absorbance
(transmittance if it was a radiator). line as a unidimensional medium
and reflection as the form of "redistribute energy" (is it OK?) and a
coherent light source for the voltage source, but I am still trying to
visualze the optical equivalent of source resistance and its job to be
a good analog, Also I am interested in check other values and
conditions in your other article (first part) with 45 degree line.

I don't think a laser source handles reflected energy like an RF amp
does. So, to start with, let's avoid reflected energy being incident
upon the laser source. Here is a good example to start with, a 1/4WL
non-reflective coating on glass.

Laser-----air-------|--1/4WL thin-film, r = 1.2222---|---Glass, r =
1.4938---...

The 1/4WL thin-film coating on the glass acts exactly like a 1/4WL
matching section of transmission line. Reflections at the air to thin-
film interface are eliminated by wave cancellation just as the FSU web
page says,

micro.magnet.fsu.edu/primer/java/scienceopticsu/interference/
waveinteractions/index.html

"... when two waves of equal amplitude and wavelength that are 180-
degrees ... out of phase with each other meet, they are not actually
annihilated, ... All of the photon energy present in these waves must
somehow be recovered or redistributed in a new direction, according to
the law of energy conservation ... Instead, upon meeting, the photons
are redistributed to regions that permit constructive interference, so
the effect should be considered as a redistribution of light waves and
photon energy rather than the spontaneous construction or destruction
of light."

Note that the reflection coefficient, r, is 1.0 for air. Thus the
SQRT[(1.0)(1.4938)] = 1.2222 ensures that reflections are eliminated
by the r = 1.2222 thin-film coating.

The same thing happens at the '+' Z0-match in the following RF system.

XMTR---50 ohm coax---+---1/4WL 300 ohm feedline---1800 ohm load

Note that SQRT[(50)(1800)] = 300 ensuring that reflections are
eliminated.
--
73, Cecil, w5dxp.com

On 27 mayo, 12:34, Cecil Moore wrote:
On May 27, 9:50*am, lu6etj wrote:

I am reading this newsgroup through Google groups web page and I just
realized that later replies to previous post are intercalated in the
thread, while I expected to see it always at the end of it, for that
reason I did not ACK before to it. (I hope yours be the only one, I
will review all thread tho chek for others).

I am also using Google since ATT dropped Usenet. I liked Thunderbird a
lot better than Google's usenet interface but I am adapting. The above
information is good to know. Thunderbird has a way to keep up with
unread vs read postings but Google doesn't seem to - at least I don't
know how to do it on Google.

In a early post I wrote = "of course if we insert a circulator to
separate both powers, generator now would see 1 ohm load, could
develope 1 W incident, 0 W reflected (Pn=1W) on circulator input, 0.36
W would be outputting on the other port to render 0.64 W (Pn) to the
load with 1 W Pf and 0,36 W Pr again"
Is this result OK for you?.

The SGCR source is usually designed for 50 ohms, i.e. the signal
generator always "sees" a 50 ohm load because it does not "see" any
reflected energy. The ideal circulator is usually designed with 50 ohm
line and a 50 ohm load resistor. If we could stick with that
particular configuration for the SGCR source, it would aid in my
understanding what is the actual system configuration, i.e. not your
fault but I am confused by your above posting.

I am interested in your optic analogy, I can imagine the load as a
partially reflecting surface, real part of it as absorbance
(transmittance if it was a radiator). line as a unidimensional medium
and reflection as the form of "redistribute energy" (is it OK?) and a
coherent light source for the voltage source, but I am still trying to
visualze the optical equivalent of source resistance and its job to be
a good analog, Also I am interested in check other values and
conditions in your other article (first part) with 45 degree line.

I don't think a laser source handles reflected energy like an RF amp
does. So, to start with, let's avoid reflected energy being incident
upon the laser source. Here is a good example to start with, a 1/4WL
non-reflective coating on glass.

Laser-----air-------|--1/4WL thin-film, r = 1.2222---|---Glass, r =
1.4938---...

The 1/4WL thin-film coating on the glass acts exactly like a 1/4WL
matching section of transmission line. Reflections at the air to thin-
film interface are eliminated by wave cancellation just as the FSU web
page says,

micro.magnet.fsu.edu/primer/java/scienceopticsu/interference/
waveinteractions/index.html

"... when two waves of equal amplitude and wavelength that are 180-
degrees ... out of phase with each other meet, they are not actually
annihilated, ... All of the photon energy present in these waves must
somehow be recovered or redistributed in a new direction, according to
the law of energy conservation ... Instead, upon meeting, the photons
are redistributed to regions that permit constructive interference, so
the effect should be considered as a redistribution of light waves and
photon energy rather than the spontaneous construction or destruction
of light."

Note that the reflection coefficient, r, is 1.0 for air. Thus the
SQRT[(1.0)(1.4938)] = 1.2222 ensures that reflections are eliminated
by the r = 1.2222 thin-film coating.

The same thing happens at the '+' Z0-match in the following RF system.

XMTR---50 ohm coax---+---1/4WL 300 ohm feedline---1800 ohm load

Note that SQRT[(50)(1800)] = 300 ensuring that reflections are
eliminated.
--
73, Cecil, w5dxp.com

May we advance in little steps to ensure we share basic assumptions?

1) I did not think of (or is think on?) a laser source, I was one step
before, I think only of a "coherent" source to match monofrequency
simple AC generator analogy.
2) What would be Rs optical analog?
3) Superposition is a medium phenomenon ¿yes?, for example "eter".
Interference an result of it on a other "thing", for example
photographic plate or screen. Are we agree? K

On May 27, 9:10*pm, lu6etj wrote:
On 27 mayo, 12:34, Cecil Moore wrote:



On May 27, 9:50*am, lu6etj wrote:

I am reading this newsgroup through Google groups web page and I just
realized that later replies to previous post are intercalated in the
thread, while I expected to see it always at the end of it, for that
reason I did not ACK before to it. (I hope yours be the only one, I
will review all thread tho chek for others).

I am also using Google since ATT dropped Usenet. I liked Thunderbird a
lot better than Google's usenet interface but I am adapting. The above
information is good to know. Thunderbird has a way to keep up with
unread vs read postings but Google doesn't seem to - at least I don't
know how to do it on Google.

In a early post I wrote = "of course if we insert a circulator to
separate both powers, generator now would see 1 ohm load, could
develope 1 W incident, 0 W reflected (Pn=1W) on circulator input, 0..36
W would be outputting on the other port to render 0.64 W (Pn) to the
load with 1 W Pf and 0,36 W Pr again"
Is this result OK for you?.

The SGCR source is usually designed for 50 ohms, i.e. the signal
generator always "sees" a 50 ohm load because it does not "see" any
reflected energy. The ideal circulator is usually designed with 50 ohm
line and a 50 ohm load resistor. If we could stick with that
particular configuration for the SGCR source, it would aid in my
understanding what is the actual system configuration, i.e. not your
fault but I am confused by your above posting.

I am interested in your optic analogy, I can imagine the load as a
partially reflecting surface, real part of it as absorbance
(transmittance if it was a radiator). line as a unidimensional medium
and reflection as the form of "redistribute energy" (is it OK?) and a
coherent light source for the voltage source, but I am still trying to
visualze the optical equivalent of source resistance and its job to be
a good analog, Also I am interested in check other values and
conditions in your other article (first part) with 45 degree line.

I don't think a laser source handles reflected energy like an RF amp
does. So, to start with, let's avoid reflected energy being incident
upon the laser source. Here is a good example to start with, a 1/4WL
non-reflective coating on glass.

Laser-----air-------|--1/4WL thin-film, r = 1.2222---|---Glass, r =
1.4938---...

The 1/4WL thin-film coating on the glass acts exactly like a 1/4WL
matching section of transmission line. Reflections at the air to thin-
film interface are eliminated by wave cancellation just as the FSU web
page says,

micro.magnet.fsu.edu/primer/java/scienceopticsu/interference/
waveinteractions/index.html

"... when two waves of equal amplitude and wavelength that are 180-
degrees ... out of phase with each other meet, they are not actually
annihilated, ... All of the photon energy present in these waves must
somehow be recovered or redistributed in a new direction, according to
the law of energy conservation ... Instead, upon meeting, the photons
are redistributed to regions that permit constructive interference, so
the effect should be considered as a redistribution of light waves and
photon energy rather than the spontaneous construction or destruction
of light."

Note that the reflection coefficient, r, is 1.0 for air. Thus the
SQRT[(1.0)(1.4938)] = 1.2222 ensures that reflections are eliminated
by the r = 1.2222 thin-film coating.

The same thing happens at the '+' Z0-match in the following RF system.

XMTR---50 ohm coax---+---1/4WL 300 ohm feedline---1800 ohm load

Note that SQRT[(50)(1800)] = 300 ensuring that reflections are
eliminated.
--
73, Cecil, w5dxp.com

May we advance in little steps to ensure we share basic assumptions?

1) I did not think of (or is think on?) a laser source, I was one step
before, I think only of a "coherent" source to match monofrequency
simple AC generator analogy.
2) What would be Rs optical analog?
3) Superposition is a medium phenomenon ¿yes?, for example "eter".
Interference an result of it on a other "thing", for example
photographic plate or screen. Are we agree? K

On Thu, 27 May 2010 19:10:41 -0700 (PDT), lu6etj
wrote:

2) What would be Rs optical analog?

Superman's cataracts with his xray vision. This is probably going to
be your only direct answer.

73's
Richard Clark, KB7QHC

On May 27, 9:10*pm, lu6etj wrote:
1) I did not think of (or is think on?) a laser source, I was one step
before, I think only of a "coherent" source to match monofrequency
simple AC generator analogy.

Let's consider an *ideal* single-frequency laser to be a coherent
monofrequency source for the purposes of discussion.

2) What would be Rs optical analog?

I don't know enough about lasers to answer that question. In any case,
I don't think reflections incident upon a laser encounter whatever Rs
that might exist. I think we are going to have to settle for what
happens outside of the laser which in important because what happens
to photons in free space and other mediums cannot be hidden inside a
transmission line. Standing waves of photons cannot stand still in a
coaxial transmission line any better than they can stand still in free
space.

What some people are missing is that visible light waves and RF waves
are exactly the same phenomena, just at a different frequency. The
laws of physics governing light waves also govern RF waves. When
someone says, "RF waves are different from light waves" or "RF waves
can stand still", they are just showing their ignorance. They must
also prove that reflected visible light waves in free space contain no
energy and can stand still or else they are just blowing smoke.

3) Superposition is a medium phenomenon ¿yes?, for example "eter".
Interference an result of it on a other "thing", for example
photographic plate or screen. Are we agree? K

No, in our context, superposition is the merging of two or more EM
waves in any medium. If the waves are coherent, constructive/
destructive interference can occur. If partial or complete wave
cancellation (permanent destructive interference) occurs, then the
energy in the waves that existed before cancellation must be
redistributed in another direction AND there are only two directions
in an RF transmission line.

I believe that Walter Maxwell defines any reversal in direction of
reflected energy flow in a transmission line to be a "re-reflection".
I prefer to call what happens to a single reflected wave a 1. "re-
reflection" and what happens when two waves cancel a 2.
"redistribution" of reflected energy.

What about the third point? I consider it important because
light waves are in three dimensional space, ...

Let's compare coax with 0.2 square inches of cross-sectional area to a
laser beam with 0.2 square inches of cross-sectional area. For the
same power level, the power density, watts/in^2, will be the same -
therefore the Poynting vectors will be the same. With such a concept
in place, we can talk about a 100w RF source or a 100w laser source.
--
73, Cecil, w5dxp.com

On May 27, 10:34*am, Cecil Moore wrote:
Note that the reflection coefficient, r, is 1.0 for air.

Sorry, I misspoke here. Instead of "reflection coefficient", I should
have said "index of refraction". The two are related but they are not
the same parameter.
--
73, Cecil, w5dxp.com