question about wire antenna and tuner
 

Ian White GM3SEK wrote:
If you measured the impedance of that incorrect antenna, and then
replaced the antenna with a dummy load of the same impedance (a resistor
of the correct value, in series with an inductor/capacitor of the
correct value) then your transmitter will not know the difference.

It is true that transmitters are dumb as a stump. However,
a human being should be smart enough to realize that the
virtual impedance, which is only a voltage to current ratio
has been replaced by an impedor with a resistor, inductor,
and/or capacitor.

The impedor *causes* the load conditions. That virtual voltage
to current ratio is a *result* and not the cause of anything.
To get down to the actual cause of the conditions, the human
being needs to know whether the load impedance is virtual or
not.

Why do you imply that a virtual impedance can *cause* the
conditions seen by a source but deny that a virtual impedance
can *cause* 100% re-reflection? Seems a contradiction.
In fact, virtual impedances cannot cause anything. The
voltage to current ratio associated with a virtual impedance
is a *result* of something physical. Choosing to ignore that
physical "something else" cause has gotten lots of folks into
logical trouble.

In the huge majority of applications, both amateur and professional, it
IS possible to separate those two topics cleanly and completely. It
seems perverse to tangle them together unnecessarily.

It seems perverse to say the antenna system can be replaced
by a resistor and inductor or capacitor and nothing changes.
How about the radiation pattern? Does that change?

It should be
absolutely no surprise that, when summed to an infinite number of terms,
this series produces exactly the same results as the steady-state model
- exactly the same pattern of standing waves, and exactly the same load
impedance presented to the transmitter.

How about the total energy in the steady-state system? The
number of joules pumped into the system during the transient
state is *exactly* the amount required to support the forward
and reflected power readings.

The important conclusion from this more detailed time-dependent analysis
is that re-reflections at the transmitter have NO effect on the final
steady-state pattern of standing waves.

This is based on a rather glaring rule-of-thumb assumption,
that any standing wave energy dissipated in the source was
never sourced to begin with. Born of necessity, that is a
rather rash assumption. Thus some people sweep the reflected
energy dissipated in the source under the rug and forget
about it, hoping that nobody ever lifts the rug and points
out the conservation of energy principle.

I await the inevitable photon explanation.

None needed. If anyone wishes to introduce additional complications
where none are necessary, then of course they're at liberty to do so.
But when invited to join in, everyone else is at liberty to decline.

Optical physicists did not have the
luxury of dealing with voltages. As a result of dealing with
power densities, they learned a lot more than RF engineers
know to this very day. Optical physicists have never asserted
that reflected waves are devoid of ExB joules/sec or that
EM waves are capable of "sloshing around".
--
73, Cecil http://www.w5dxp.com

question about wire antenna and tuner
 

Roy Lewallen wrote:
People who believe
that "reflected power" ends up heating up the transmitter should take a
careful look at this, and see if they can explain it.

I have taken a careful look and have explained it using the
principles of destructive vs constructive interference between
EM waves adopted from the field of optical physics. Power density
in any EM wave is proportional to ExB and that includes reflected
waves in a transmission line. Your attempt to ignore the technical
facts about the necessity for energy content in reflected waves is
pretty obvious.

But they can never come up with a coherent reason for
the results shown in the essay table, or equations which will predict
just how much "reflected power" a transmitter will absorb and when. And
the reason is just as Ian said.

It is untrue that those coherent reasons do not exist. I have
pointed out those "reasons and results from the field of optical
physics and you have simply chosen to sweep them under a rug.

Unfortunately, some people, when presented clear evidence that the
concept is wrong, cling desperately to it nonetheless.

Unfortunately, some people, when presented with clear evidence
that everything is explained perfectly by interference phenomena
and the conservation of energy principle, cling desperately to
"sloshing" EM waves and reflected EM waves devoid of any energy
content - something to do with motes and beams.
--
73, Cecil http://www.w5dxp.com

question about wire antenna and tuner
 

Roy Lewallen wrote:
Once a black cat walked across the street in front of me. I had a
wonderful day! The wonderful day was real, whatever the theory behind
it. My basis for crediting the cat is just as valid as yours for
crediting "reflected energy" for the heating. And based on similar logic.

One can mentally install a one-wavelength piece of lossless
transmission line between the source and load which will
allow one to analyze the interference patterns. Constructive
interference toward the source certainly can cause heating
of the source in perfect accordance with the conservation
of energy principle.
--
73, Cecil http://www.w5dxp.com

question about wire antenna and tuner
 

Highland Ham wrote:
Roy Lewallen wrote:
But I did write up a lengthy essay several years ago, in response to
the same insistent rantings about reflecting waves of average power
that's still going on in this newsgroup, and it has some numerical
examples with a very simple circuit which illustrate the problems with
what you said. You can get it at
http://eznec.com/misc/Food_for_thought.pdf.
===========================
Roy ,Tnx vy much for that ,much appreciated. ( it now sits in my
'Antenna' file)

Unfortunately, all it proves is that reflected power
doesn't always cause heating of the source. It does
not prove that reflected power never causes heating
of the source but that seems to be what w7el would
have us believe that he has proven.

If constructive interference between reflected waves
is in the direction of the load, the source will run
cool and the load will run hot. An antenna tuner can
accomplish that configuration.

If constructive interference energy flows unimpeded
backwards into the source without being re-reflected,
the source will run hot and the load will run cool.

This is no-brainer conservation of energy stuff.
Simply calculate the total number of joules contained
in the closed system and observe where those joules go.
Hint: the total number of joules contained in the
system are *exactly* the number of joules needed to
support the joules/sec in the forward and reflected
power readings.
--
73, Cecil http://www.w5dxp.com

question about wire antenna and tuner
 

Roy Lewallen wrote:
Once a black cat walked across the street in front of me. I had a
wonderful day! The wonderful day was real, whatever the theory behind
it. My basis for crediting the cat is just as valid as yours for
crediting "reflected energy" for the heating. And based on similar logic.

But, once again, you left out some important details.
The black cat belonged to your neighbor who gave you
$100 for not running over it and that's why you had
a wonderful day. :-)
--
73, Cecil http://www.w5dxp.com

question about wire antenna and tuner
 

On Sun, 4 Nov 2007 22:10:19 -0700, "Sal M. Onella"
wrote:


"Owen Duffy" wrote in message
...
"Sal M. Onella" wrote in
:

as heat somewhere in the system. If too much is reflected back from
the antenna and dissipated within in your transmitter, the transmitter
overheats ($$$) or it reduces power to protect itself and nobody hears
you.

Here we go again!

Owen

What did I say wrong?

You offered only half the evidence, as in the following instance:

On Sun, 4 Nov 2007 22:30:30 -0700, "Sal M. Onella"
wrote:


"Cecil Moore" wrote in message
...
Roy Lewallen wrote:
Yes, this misconception will never die. Is it really worth the trouble
continually trying to contradict it?

Not if all you do is trade one old-wives tale
for another.

It's hardly an old wives' tale.

I mistakenly put a 2m antenna on my dual band HT and tried to use it for a
short QSO on a nearby 440 repeater. The other ham said I was barely making
the repeater, while my poor HT got so hot that I could barely hold it after
a minute's use.

The antenna was wrong and the heat was real -- whatever the theory behind
it.

In the explanations that hammered you for your naivete, there was no
support of what was obvious to you, and perfectly acceptable as a true
portion of a complete description. You testified to the experience of
observing more heat where odds would have had you as likely testifying
to the experience of observing less heat. We get none of those "less
heat" reports because they naturally go unobserved. This is simply
the common response to a psychomotor lesson instructed from Mom who I
am sure warned you to "never stick your hand in the oven" but probably
never uttered "never stick your hand in the ice-box." The first bears
warning for its obvious consequences, the second hardly demands
mentioning where its consequence is far less dramatic.

So we have these dramas over heat and the stage is filled with tenors
crying their lungs out about the evils of misunderstandings (the last
act of "Romeo and Juliet" comes to mind).

We should also first establish that your HT also exhibits waste heat.
As no common transmitter of notable power is 100% efficient, it is
raising its heat content in relation to its surroundings. If your
hand temperature is cooler than that case surface, you note heating;
contrariwise, if your hand temperature is warmer than that surface,
you note cooling. As almost every item within reach of you is at room
temperature and you rarely note it as cooler, it is hardly worth
mentioning.

Your's was a sin of omission and what "you said wrong" was more in
that neglect of mentioning all the cooling experiences in your life
when your HT was mismatched. Of all the web pages, treatises, papers,
tomes, chapters and verses dedicated to eradicating the myth of
reflected power, all of them are equally sinful in their omissions.
You are not alone there in Reflected Power Hell.

Let's begin first with "reflected power." It is in fact reflected
energy that is noteworthy here, power is merely the manifestation of
energy at a load. With this discussion of the HT and an antenna,
there are two loads (and this raises the tenor's volume of agony
another octave - I will leave that Operetta for other discussion).

The HT as a load is already exhibiting waste heat. Everyone's
experience of operating one for several minutes will testify to that
(yes, more anecdotal evidence) even when it is pushing energy into a
matched load. Let's take the experience of your mismatch and put that
antenna on a variable transmission line (one of those bench top tools,
aka the "Sliding Load," few here have had experience with) and run the
line through 360° of variation as noted at the source (your HT). This
study will fill in all those omissions from those publications so
cleverly painted up and distributed across the web as sage advice.

When that returned energy meets the source energy and combines at the
source, there are 360° of variation possible outcomes. This
combination can be in series aiding, in series opposition, or in all
points in between. This will be a function of the length of the
variable line. You add two aiding energies to the same load and it
will raise its temperature against waste heat. You add two opposing
energies to the same load and it will subdue its temperature against
waste heat. These are the extreme outcomes that fall 180° apart based
on the length of that variable transmission line. One outcome burns
your hand, as you've already noted, the other does not (and you
neglected to inform us of all those occasions you naughty boy!). All
the combinations in between were by relation, inconsequential, and
passed unnoticed (even more sins of omission).

Hence, the problem of anecdotal evidence is that it does not report
fully. However, applying the label "anecdotal" does not automatically
invalidate the observer's credible but isolated reporting; it merely
demands a fuller examination. Unfortunately, you were denied this
full examination in the criticism of your true observation. You
observed one data point and perhaps were guilty of expanding it to
describe a general condition = reflected power always heats a source.
In fact, reflected energy can heat or cool a source in relation to its
existing waste heat. The degree of heating or cooling is found in the
magnitude of the mismatch, and the number of degrees that separate the
load and the source.

As for all the side comments about how "reflections" do not contain
(fill in the blank) ______; and that these issues are instead answered
by Impedance relationships instead - Baloney cut thick. Reflections
AND Impedance relationships occupy opposite sides of the same coin and
are equally applicable. This concept of mutuality is so ingrained in
the catechism of RF as to taint anyone who denies one explanation for
the sake of the other as evidence of some special circumstance. In
this regard, you were sinned against in kind. ;-)

73's
Richard Clark, KB7QHC

question about wire antenna and tuner
 

Cecil Moore wrote:
Ian White GM3SEK wrote:
If you measured the impedance of that incorrect antenna, and then
replaced the antenna with a dummy load of the same impedance (a
resistor of the correct value, in series with an inductor/capacitor
of the correct value) then your transmitter will not know the difference.

It is true that transmitters are dumb as a stump. However,
a human being should be smart enough to realize that the
virtual impedance, which is only a voltage to current ratio
has been replaced by an impedor with a resistor, inductor,
and/or capacitor.

The impedor *causes* the load conditions. That virtual voltage
to current ratio is a *result* and not the cause of anything.

At the terminals of the load, both the voltage and current are
physically real and physically measurable, as also is the phase angle
between them. Their ratio is the (complex) load impedance as seen by the
transmitter.

Any device that creates those same electrical conditions possesses the
same impedance; by definition.

The transmitter affects the magnitude of the voltage and current in the
load, but it categorically does NOT affect their ratio, or the phase
angle. In other words, the transmitter has no effect on the value of the
impedance that is connected to it as a load, That value is created
exclusively by the load.


To get down to the actual cause of the conditions, the human
being needs to know whether the load impedance is virtual or
not.


I can see your underlying point, about the difference between a lumped
impedance physically present at the transmitter output terminals, and an
impedance created by 'action at a distance' through a transmission line.
But if both kinds of load create the SAME steady-state voltage:current
ratio and phase angle at the transmitter output terminals, then by
definition they both have the SAME impedance, and the transmitter will
respond in EXACTLY the same way. There is no steady-state measurement
you can possibly make on the transmitter than can tell the difference
between those two different kinds of load.

That principle is absolutely fundamental. It underlies all steady-state
impedance measurements using bridges, network analysers etc. Regardless
of the nature of the DUT (device under test), you connect it to the
meter, measure what you find, and that IS "the impedance of the DUT".

The differences only appear if you change frequency, or if you make a
time-dependent measurement, but there is never a difference in the
steady state.


Why do you imply that a virtual impedance can *cause* the
conditions seen by a source but deny that a virtual impedance
can *cause* 100% re-reflection? Seems a contradiction.
In fact, virtual impedances cannot cause anything. The
voltage to current ratio associated with a virtual impedance
is a *result* of something physical. Choosing to ignore that
physical "something else" cause has gotten lots of folks into
logical trouble.

I invite you to consider another possibility: that the people who have
chosen to stick with the established textbook analyses are not ignoring
anything, and they are in no kind of logical trouble because those
analyses are both logical and consistent; and that the only person in
logical trouble is actually yourself, because you are making
distinctions between different varieties of impedance that do not exist.


In the huge majority of applications, both amateur and professional,
it IS possible to separate those two topics cleanly and completely. It
seems perverse to tangle them together unnecessarily.

It seems perverse to say the antenna system can be replaced
by a resistor and inductor or capacitor and nothing changes.
How about the radiation pattern? Does that change?


Nothing changes in the part of the system I was talking about, namely AT
the transmitter/load interface. (Lord, gimme strength...)

It should be absolutely no surprise that, when summed to an infinite
number of terms, this series produces exactly the same results as the
steady-state model - exactly the same pattern of standing waves, and
exactly the same load impedance presented to the transmitter.

How about the total energy in the steady-state system? The
number of joules pumped into the system during the transient
state is *exactly* the amount required to support the forward
and reflected power readings.

If you say so; but nobody else feels the need to calculate those
quantities.

The important conclusion from this more detailed time-dependent
analysis is that re-reflections at the transmitter have NO effect on
the final steady-state pattern of standing waves.

This is based on a rather glaring rule-of-thumb assumption,
that any standing wave energy dissipated in the source was
never sourced to begin with. Born of necessity, that is a
rather rash assumption. Thus some people sweep the reflected
energy dissipated in the source under the rug and forget
about it, hoping that nobody ever lifts the rug and points
out the conservation of energy principle.

All valid solutions to the problem of AC/RF generators, transmission
lines and loads will most assuredly comply with the conservation of
energy! But countless textbooks show that it isn't necessary to invoke
that principle in order to make a valid analysis.


I await the inevitable photon explanation.

None needed. If anyone wishes to introduce additional complications
where none are necessary, then of course they're at liberty to do so.
But when invited to join in, everyone else is at liberty to decline.

Optical physicists did not have the
luxury of dealing with voltages. As a result of dealing with
power densities, they learned a lot more than RF engineers
know to this very day. Optical physicists have never asserted
that reflected waves are devoid of ExB joules/sec or that
EM waves are capable of "sloshing around".

But WE DO enjoy the luxury of having complete information on voltages,
currents and phase angles, at any instant and at every point along a
transmission line. That allows us to obtain complete solutions without
dragging in unnecessary concepts from other disciplines.



--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

question about wire antenna and tuner
 

Ian White GM3SEK wrote:
Any device that creates those same electrical conditions possesses the
same impedance; by definition.

Sorry Ian, that's just not true. There are three separate
definitions for impedance in "The IEEE Dictionary". If all
those were the same impedance, they wouldn't need three
definitions. A resistor has a resistance. The Z0 of a
transmission line is a resistance. They are NOT the same
impedance, by definition. The IEEE Dictionary says:
"Definition (C) is a second use of "impedance" and is
independent of definitions (A) and (B)." (C) is the
definition of impedance associated with a resistor,
inductor, or capacitor. (B) is the definition of impedance
associated with a voltage to current ratio. The IEEE
Dictionary goes out of its way to explain that there is
a difference.


The transmitter affects the magnitude of the voltage and current in the
load, but it categorically does NOT affect their ratio, or the phase
angle.

Strawman

But if both kinds of load create the SAME steady-state voltage:current
ratio and phase angle at the transmitter output terminals, then by
definition they both have the SAME impedance, and the transmitter will
respond in EXACTLY the same way.

Although they may have the same value of impedance components,
they are NOT the same impedance, by IEEE definition. See above.

That principle is absolutely fundamental.

Too bad that your underlying absolutely fundamental
principle is wrong according to the IEEE Dictionary.

... because you are making
distinctions between different varieties of impedance that do not exist.

I'm just following the IEEE lead. You, OTOH, are in
logical trouble for disagreeing with the IEEE.

All valid solutions to the problem of AC/RF generators, transmission
lines and loads will most assuredly comply with the conservation of
energy! But countless textbooks show that it isn't necessary to invoke
that principle in order to make a valid analysis.

Please show me a textbook that gives you permission to
ignore the conservation of energy principle.

But WE DO enjoy the luxury of having complete information on voltages,
currents and phase angles, at any instant and at every point along a
transmission line. That allows us to obtain complete solutions without
dragging in unnecessary concepts from other disciplines.

But you guys even ignore the laws of physics for electrical
engineering, e.g. Vfor*Ifor=Pfor and Vref*Iref=Pref
--
73, Cecil http://www.w5dxp.com

question about wire antenna and tuner
 

Ian White GM3SEK wrote in
:

Ian, an excellent and quite comprehensive treatment.

Sal,

Some folk will try to distract from an adequately accurate approximation
(being the steady state solution) by wanting to descend to a time domain
solution which as you note converges to the steady state solution in
time, but is much more complex to solve.

The relevance of steady state solutions is demonstrated by the
traditional methods of designing transmission line transformers (eg
quarter wave match), stub matching schemes, the application of the Smith
chart etc. These things are only valid on applications where a steady
state solution is valid, and the widespread use of them attests to the
widespread existence of systems that are quite adequately analysed by
steady state methods.

Most ham applications are ones where the highest modulating frequency is
very small wrt the carrier frequency, and are emminently suited to steady
state analysis.

Similarly, consider that when steady state analysis is not appropriate,
then many of the devices mentioned above may be inappropriate as they
will cause distortion of the signal.

Owen

question about wire antenna and tuner
 

"Richard Clark" wrote in message
...
On Sun, 4 Nov 2007 22:10:19 -0700, "Sal M. Onella"
wrote:


"Owen Duffy" wrote in message
...
"Sal M. Onella" wrote in
:

as heat somewhere in the system. If too much is reflected back from
the antenna and dissipated within in your transmitter, the
transmitter
overheats ($$$) or it reduces power to protect itself and nobody
hears
you.

Here we go again!

Owen

What did I say wrong?

You offered only half the evidence, as in the following instance:

On Sun, 4 Nov 2007 22:30:30 -0700, "Sal M. Onella"
wrote:


"Cecil Moore" wrote in message
...
Roy Lewallen wrote:
Yes, this misconception will never die. Is it really worth the
trouble
continually trying to contradict it?

Not if all you do is trade one old-wives tale
for another.

It's hardly an old wives' tale.

I mistakenly put a 2m antenna on my dual band HT and tried to use it for
a
short QSO on a nearby 440 repeater. The other ham said I was barely
making
the repeater, while my poor HT got so hot that I could barely hold it
after
a minute's use.

The antenna was wrong and the heat was real -- whatever the theory behind
it.

In the explanations that hammered you for your naivete, there was no
support of what was obvious to you, and perfectly acceptable as a true
portion of a complete description. You testified to the experience of
observing more heat where odds would have had you as likely testifying
to the experience of observing less heat. We get none of those "less
heat" reports because they naturally go unobserved. This is simply
the common response to a psychomotor lesson instructed from Mom who I
am sure warned you to "never stick your hand in the oven" but probably
never uttered "never stick your hand in the ice-box." The first bears
warning for its obvious consequences, the second hardly demands
mentioning where its consequence is far less dramatic.

So we have these dramas over heat and the stage is filled with tenors
crying their lungs out about the evils of misunderstandings (the last
act of "Romeo and Juliet" comes to mind).

We should also first establish that your HT also exhibits waste heat.
As no common transmitter of notable power is 100% efficient, it is
raising its heat content in relation to its surroundings. If your
hand temperature is cooler than that case surface, you note heating;
contrariwise, if your hand temperature is warmer than that surface,
you note cooling. As almost every item within reach of you is at room
temperature and you rarely note it as cooler, it is hardly worth
mentioning.

Your's was a sin of omission and what "you said wrong" was more in
that neglect of mentioning all the cooling experiences in your life
when your HT was mismatched. Of all the web pages, treatises, papers,
tomes, chapters and verses dedicated to eradicating the myth of
reflected power, all of them are equally sinful in their omissions.
You are not alone there in Reflected Power Hell.

Let's begin first with "reflected power." It is in fact reflected
energy that is noteworthy here, power is merely the manifestation of
energy at a load. With this discussion of the HT and an antenna,
there are two loads (and this raises the tenor's volume of agony
another octave - I will leave that Operetta for other discussion).

The HT as a load is already exhibiting waste heat. Everyone's
experience of operating one for several minutes will testify to that
(yes, more anecdotal evidence) even when it is pushing energy into a
matched load. Let's take the experience of your mismatch and put that
antenna on a variable transmission line (one of those bench top tools,
aka the "Sliding Load," few here have had experience with) and run the
line through 360° of variation as noted at the source (your HT). This
study will fill in all those omissions from those publications so
cleverly painted up and distributed across the web as sage advice.

When that returned energy meets the source energy and combines at the
source, there are 360° of variation possible outcomes. This
combination can be in series aiding, in series opposition, or in all
points in between. This will be a function of the length of the
variable line. You add two aiding energies to the same load and it
will raise its temperature against waste heat. You add two opposing
energies to the same load and it will subdue its temperature against
waste heat. These are the extreme outcomes that fall 180° apart based
on the length of that variable transmission line. One outcome burns
your hand, as you've already noted, the other does not (and you
neglected to inform us of all those occasions you naughty boy!). All
the combinations in between were by relation, inconsequential, and
passed unnoticed (even more sins of omission).

Hence, the problem of anecdotal evidence is that it does not report
fully. However, applying the label "anecdotal" does not automatically
invalidate the observer's credible but isolated reporting; it merely
demands a fuller examination. Unfortunately, you were denied this
full examination in the criticism of your true observation. You
observed one data point and perhaps were guilty of expanding it to
describe a general condition = reflected power always heats a source.
In fact, reflected energy can heat or cool a source in relation to its
existing waste heat. The degree of heating or cooling is found in the
magnitude of the mismatch, and the number of degrees that separate the
load and the source.

As for all the side comments about how "reflections" do not contain
(fill in the blank) ______; and that these issues are instead answered
by Impedance relationships instead - Baloney cut thick. Reflections
AND Impedance relationships occupy opposite sides of the same coin and
are equally applicable. This concept of mutuality is so ingrained in
the catechism of RF as to taint anyone who denies one explanation for
the sake of the other as evidence of some special circumstance. In
this regard, you were sinned against in kind. ;-)

73's
Richard Clark, KB7QHC

So, when you were on staff at USN ET "A" School, where we both taught, did
you know better than the "reflected power" legend/old-wives-tale/heresy?
Hell, that's where I first picked it up !!!!!!!!!!!!!!!

John