Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

Standing morphing to travelling waves, and other stupid notions
 

On Jan 9, 3:30 pm, Gene Fuller wrote:
So do we now have a new requirement for waves and photons that there
must be *net* energy flow?

It's not a new requirement, Gene, just a very old requirement of
physics. Photonic, i.e. EM waves, do not flow back and forth as you
are implying. As long as the medium is homogeneous, i.e. doesn't
change, a photon travels at the speed of light in one direction in a
medium. So yes, net energy flow is absolutely a requirement for
photons.

EM waves *are* photons and do not vibrate back and forth in a medium.
They travel in one direction at the speed of light in the medium until
they encounter an impedance discontinuity. Virtually any physics book
with a diagram of the EM wave E-field and H-field will show the
direction of travel as one direction without the "one step forward and
one step back" concept that you are proposing.

You claimed that standing waves cannot be real waves because they cannot
obey photon rules. I easily demonstrated that idea is incorrect.v

All you demonstrated was your ignorance of the nature of photons. Your
analysis was incorrect. You are seeing the standing wave illusion and
assuming an impossibility of physics. It is very clear that you and
others simply do not understand the nature and physics of photons and
photonic waves.
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

Roy Lewallen wrote:
wrote:
On Jan 9, 11:03 am, Michael Coslo wrote:
AI4QJwrote:
The NEC program is just a computer model, for discussion purposes
only. I
think there are far too many variables in real life for the program
to take
into account. It may be valuable but I am not yet convinced it is
infallible.
Oh darnit! Here I went and built several antennas designed
with Eznec,
and they have worked just like the program said they would.

I guess I'll have to take the remaining ones down, since I
was only
supposed to discuss them, not actually make and use them. Thanks for the
correction!

- 73 de Mike N3LI -

But you may have a problem discussing on the ng exactly "why" they
work. Why would you want to discuss an antenna if you don't care "how"
it works, you only care "that" it works? There are some people that
operate at 27MHz who don't care how their radios work, only that they
can peg your meter at 10 pounds.

A whole lot of people have gained a better understanding of why antennas
work by using computer modeling. They observe how they work, discover
it's not how they thought they worked, and are prodded into learning why
they work. I've learned a great deal myself this way, and many
conversations with EZNEC users over the years shows this to be a common
benefit from modeling. It allows you to immediately see if your concepts
are sound by showing you the results of their application. NEC and EZNEC
don't design antennas; they only tell you how the antenna you've
designed works. Chances are you won't design a very effective antenna if
you have no idea why they work. People truly interested in learning more
about why antennas work will arm themselves with as many available tools
as possible.

A recent example of this philosophy was the transmission line analysis I
recently posted. After working through all the math, which came from a
basic understanding of transmission line analysis, I simulated the line
with SPICE to confirm that my analysis was correct. Had it shown
something different, I would have gone back to the math, or the model,
or my basic view of transmission line operation, to resolve the
discrepancy.

Arguments against using computer programs for antenna analysis are about
the same as those against using a calculator to perform arithmetic. No,
on second thought, more like arguing against using a computer to solve
systems of differential equations.

But, each to his own.

Roy Lewallen, W7EL

Computer modeling is wonderful ...

Constant examination and keeping it up-to-date will allow it to hold
this status ... it is hardly in a finished form ...

Regards,
JS

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

Roy Lewallen wrote:
Corrections:

The equations I gave aren't adequate for complex reflection
coefficients, which I didn't explicitly state. Also, I inadvertently
omitted a multiplying factor in two equations.
...
Roy Lewallen, W7EL

Or, in honest terms, "forget about anything 'unifying', to make this ten
gorilla float it is going to take tons of "special cases."

In my humble opinion, complete proof "something is missing." I do NOT
claim to know what that "something" is, only that it is QUITE obvious!

Regards,
JS

Standing morphing to travelling waves, and other stupid notions
 

On Jan 9, 3:13 pm, Jim Kelley wrote:
On what page has Dr. Hecht written "a standing wave is a different
kind of electromagnetic wave"?

Since I didn't say that Dr. Hecht said that, it must be a rhetorical
question. Here's what Dr. Hecht did say: In "Schaum`s College Physics
Outline" by Bueche & Hecht on page 214 is written: "Standing
Waves:....These might better not be called waves at all since they do
not transport energy and momentum." (Thanks to Richard Harrison for
that quote.) I agree with Dr. Hecht. Standing waves should not be
called waves at all since they do not meet the definition and
requirements for EM waves.

I asserted that expression for the sum of traveling waves and the
expression for the resulting standing wave pattern are related by trig
identity, as per page 140 of the 28th Edition of the CRC Standard
Mathematical Tables Handbook.

Sorry Jim, that's not what you said. You asked if I recognized the
trig identity that (presumably) equated a standing wave to a traveling
wave. If that was not your meaning, it is time to say exactly what
meaning I was supposed to assume.

The 'wave' which stands is merely an amplitude envelope for the waves
which move.

Key word there is "waves". A standing wave is NOT self sufficient - it
requires the superposition of a forward-traveling wave and a reverse-
traveling wave. A standing wave loses its EM wave identity in the
process of that superposition and apparently creates an illusion
capable of mass hysteria. To alleviate that hysteria, one has only to
compare the equations for standing waves and traveling waves or the
corresponding graphs of those functions to see that they are hardly
anything alike.
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

On Jan 9, 3:33 pm, Gene Fuller wrote:
When you get back to the wilds of Texas go check out some rural power
lines. Count the number of power factor correcting capacitors you see. I
bet it is a lot less than the equivalent of one per city block. Power
factor correcting capacitors are intended to correct for reactive loads,
such as motors, not for reflections or standing waves on open ended
power transmission lines.

Within the city limits of my home town of Madisonville, TX, there is
approximately one capacitor every city block. I had one in my front
yard. But the exact number and distances do not matter one iota. Those
capacitors exist to neutralize the inductive reactance in the system
at the load. I use exactly the same method to twist the feedpoint
impedance of my 75m Bugcatcher to 50 ohms.

You said: "Power factor correcting capacitors are intended to correct
for reactive loads,"

:-) Reactive loads cause reflections. The opposite reactance reduces
reflections. Does that scheme of matching a transmission line to a
load sound familiar? :-) My Bugcatcher antenna has about 25=j25 ohm
feedpoint impedance on 40m. I install a -j50 cap from antenna to
ground to achieve 50+j0 at the feedpoint. That's exactly what the
power company capacitors do.

Reflections *ARE* power factor problems. When the power company brings
the power factor to unity, they have eliminated reflections and turned
the system into a traveling wave energy delivery system. That you do
not recognize the similarity between VARS and standing waves is really
strange indeed. Standing waves contain nothing except VARS.
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!
 

On Jan 9, 7:48 pm, art wrote:
Thus it is the length of the antenna by your statement is what turns
around the current regardless of the frequency applied.

The feedpoint impedance of these standing wave antennas can be closely
approximated by

Zfp = (Vfor+Vref)/(Ifor+Iref)

where all values are phasors. For instance, the reflected voltage will
be out of phase with the forward voltage at the feedpoint for a
resonant 1/2WL dipole while the reflected current will be in phase
with the forward current. The feedpoint impedance of a 1/2WL dipole is
very close to (|Vfor|-|Vref|)/(|Ifor|+|Iref|). See if you can figure
it out for other lengths of dipoles.
--
73, Cecil, w5dxp.com

Standing morphing to travelling waves, and other stupid notions
 

Just what is a "wave", anyway? Are there different "kinds" of
electromagnetic wave? If so, what are they? Does a "wave" have to travel
in order to be a "wave", or can it just "vibrate" or "oscillate"? Or
just "stand"?

Most of my references call a standing wave a "pattern". Is a "pattern" a
"wave"? Can a "wave" be a "pattern"?

That should be good for another few hundred posts, at least. Sheesh.

Roy Lewallen, W7EL

Standing morphing to travelling waves, and other stupid notions
 

After reading this, I understand why you find Art's material interesting.

But, what's a "wave"?

Roy Lewallen, W7EL

AI4QJ wrote:
"Roy Lewallen" wrote in message
...
Just what is a "wave", anyway? Are there different "kinds" of
electromagnetic wave? If so, what are they? Does a "wave" have to travel
in order to be a "wave", or can it just "vibrate" or "oscillate"? Or just
"stand"?

Most of my references call a standing wave a "pattern". Is a "pattern" a
"wave"? Can a "wave" be a "pattern"?

That should be good for another few hundred posts, at least. Sheesh.

Roy Lewallen, W7EL

Roy,

The standing wave is the mathematical sum of the forward and reflected
waves. This sum is a superposition wave. The components of the superposition
wave no longer exist by themselves; they form part of the summation which is
the non-traveling "standing wave". Like its forward and reverse components
(each containing "real" power) that would have been traveling waves prior to
superposition, and which have now ceased to exist, the summation wave is
also a real wave that vibrates at a frequency that, when multiplied by its
wavelength, equals c (but traveling nowhere), and stored with "imaginary" or
"reactive" power, where the real power components have been changed to
reactive power components. Energy is conserved. The real energy in the
traveling waves has been changed temporarily to potential or reactive VA
(Cecil calls it VAR....same thing) energy until it dissipates into the
radiation resitance by the radiation of photons/waves through free space
(ignoring ohmic losses which also dissipate real power). After dissipation
of each photon or wave into free space (where E=hf, take your pick) from the
theoretical radiation resistor, the generator (transmitter) source must
replenish energy into the antenna to keep the standing wave stored-energy
system oscillating and then depleting into radiation. Without constant
replenishment from the generator, the standing wave diminishes to zero.

It is like an inductor, capacitor and radiation "resistor", all connected in
parallel, and whose impedance is the radiation resistance of the antenna,
which itself is related to the impedance of free space and the geometry of
the antenna (as you know). What is not intuitive is where the other terminal
of the "radiation resistor" is connected. But that is indeed where the
traveling wave from the dissipated standing wave 'travels' to. That is where
I find Art's material interesting. I do not think I have ever seen a
depiction of this phenomenon that can be conceptualized but I think Art is
trying.

OK, go ahead. Lock, load and fire ;-)

AI4QJ

Standing morphing to travelling waves. was r.r.a.a Laugh Riot!!!