Constructive interference in radiowave propagation
 

Cecil Moore wrote:
Jim Kelley wrote:

Cecil Moore wrote:

True negative power just doesn't exist.
Negative energy would violate the conservation of
energy principle.


Correct. Therefore 2*sqrt(P1*P2)cos(180) is impossible as well as
ridiculous.


That's the interference term, Jim. Hecht, Born, and Wolf
all agree that the interference term can be negative.
Suggest you take a refresher course and alleviate the
ignorance you are displaying for everyone to observe.

Ah, but the ignorance being seen by all is all yours, sir. You
continue to ignore a significant detail, Cecil. See if you can find
it. Hint: people who write physics books know that power does not
interfere.

Please tell Hecht, Born, and Wolf that they are ridiculous.

I agree with them, and they don't post here. But if they did, they'd
be telling you the same thing as everyone else here.

ac6xg

Constructive interference in radiowave propagation
 

Keith Dysart wrote:
So it is settled then. There is no NEED for a forward OR reverse
travelling wave. Differential equations rule.

Yes, it is settled in your own mind. In my mind,
there is certainly a need for forward and reverse
traveling waves without which standing-waves would
not be possible. If you want to deny the existence
of the cause of standing-waves, there is nothing
I can to stop you.

Well, except for the inability to explain where the "reflected
power" goes in the transmitter. Of course this is not an issue
for carefully selected examples where no "reflected power" reaches
the transmitter. A more general analysis technique would not
require such careful selection of examples.

The more general analysis technique tells us that
the moon is 1000 miles away from the earth. I don't
know how far away the moon is but I know it is not
1000 miles away.
--
73, Cecil, http://www.qsl.net/w5dxp

Constructive interference in radiowave propagation
 

Jim Kelley wrote:
Hint:
people who write physics books know that power does not interfere.

Please tell that to someone who disagrees with
that statement, Jim, which is not me. Here's what
I said in my years old energy analysis article.

"The term 'power flow' has been avoided in favor of
'energy flow'. Power is a measure of that energy flow
per unit time through a plane. Likewise, the EM fields
in the waves do the interfering. Powers, treated as
scalars, are incapable of interference."

You keep making statements like the above in hopes
someone somewhere will believe that I disagree with
it. Old trick - doesn't work.

I say, *EM WAVES DO THE INTERFERING*. Do you want
to argue about that?

I say, *POWERS ARE INCAPABLE OF INTERFERENCE*. Do
you want to argue about that?

Please, if we are going to argue about something,
make it something upon which we disagree.
--
73, Cecil, http://www.qsl.net/w5dxp

Constructive interference in radiowave propagation
 

Cecil Moore wrote in
t:

Owen Duffy wrote:
Roy, one of the questions I continue to ask myself is why certain
explanations of transmission line / load behaviour seem inconsistent
with basic AC circuit theory as it applies at 50Hz or 60Hz, ...

That's an easy one, Owen. The wavelength is so long at
....

Cecil, you have conveniently clipped the context (as you do), the
relevant context being the line-load interface and source-line interface.

Statements in some explanations (by others) like "This clearly proves
that reflected power and forward power in a transmission line are both
real power, and that no fictitious power, or reactive volt-amperes,
exists in either one." seem incompatible with the basic AC circuit theory
explanation of a reactive load which must exchange reactive energy with
the transmission line over a complete cycle (and the same effect at the
source end).

Perhaps it is explained by hopping in an out of the instantaneous and
average context, just like switching between lossless lines and lossy
lines context with declaration, while actually carrying the analytical
simplicity of lossless lines and selectively layering selected aspects of
the loss.

BTW, I am not surprised at your dissertation apparently dismissing the
distributed impedance model of a line, because after all it is the
solution of that model that gives us the classic transmission line
equations that you seem to not want to use.

If the distributed network model you favour is the S paramater model,
properly applied, it is in fact entirely consistent with the distributed
impedance line model because the parameters are derived from the solution
to the distributed impedance line model.

Owen

Constructive interference in radiowave propagation
 

John Smith I wrote in news:evj2m0$jb7$1
@nnrp.linuxfan.it:

When I fire up the big russian 3.5KW linear into a high swr, I don't
have to guess about where the reflected power is going at the xmitter,
the nice red glow on the plates are an excellent indication when they
begin dumping unknown amounts of power as infrared radiation ... when I
grab the coax (150 ft. run) and feel its warmth, I even wonder about how
much power it takes to elevate it's temp!

John,

With that insight and rigorous development, it must be time for you to
publish a book.

Owen

Constructive interference in radiowave propagation
 

Owen Duffy wrote:

...
John,

With that insight and rigorous development, it must be time for you to
publish a book.

Owen

Owen:

How'd you guess?

Title of book, "Spontaneous Thermal Emission of RF Finals and Feedline
in Amateur Radio Systems With No Apparent Cause(s)!"

Trouble is, the book stores keep putting it with the works on fiction :-(

JS

Constructive interference in radiowave propagation
 

Owen Duffy wrote in
:

lines context with declaration, while actually carrying the analytical

That should have read "without declaration".

Constructive interference in radiowave propagation
 

Roy Lewallen, W7EL wrote:
"A real analysis of energy flow involves calculating the power at
various points and times in the circuit or transmission line of
interest."

Yes. Bird Electronic Corporation has done a good job of this with its
"Thruline" wattmeter for several decades.

Its practice is to measure in a 50-ohm Zo resistive lossless impedance
environment where forward and reflected waves are 180 regrees
out-of-phase. This allows Bird to say:
"Power delivered and dissipated in the load is given by:
Watts into Load = Wforward - Wreflected"

I would not argue with success.

Best regards, Richard Harrison, KB5WZI

Constructive interference in radiowave propagation
 

Richard Harrison wrote:
Roy Lewallen, W7EL wrote:
"A real analysis of energy flow involves calculating the power at
various points and times in the circuit or transmission line of
interest."

Yes. Bird Electronic Corporation has done a good job of this with its
"Thruline" wattmeter for several decades.
. . .

No, the Bird wattmeter measures only the average power and only at one
point. That's vastly different from what I described, which is
instantaneous power as a function of time at many points along the line.
A complete analysis of energy flow would include equations for the power
as a function of time and position. You're sadly mistaken if you think
you're getting this information from your Bird wattmeter.

Roy Lewallen, W7EL

Constructive interference in radiowave propagation
 

John Smith I wrote in news:evji53$kf9$1
@nnrp.linuxfan.it:

Owen Duffy wrote:

...
John,

With that insight and rigorous development, it must be time for you to
publish a book.

Owen

Owen:

How'd you guess?

Title of book, "Spontaneous Thermal Emission of RF Finals and Feedline
in Amateur Radio Systems With No Apparent Cause(s)!"

Trouble is, the book stores keep putting it with the works on fiction
:-(

John, it will never sell to the amateur market... you need a simple,
catchy title. If it is destined for the fiction category, you could offer
an sub title like "How reflections ruined my PA... from a ham who
survived to tell the REAL story", with "Don't let it happen to you"
emblazened in flouro red across the cover.

Seriously, simple explanations are appealing, they provide content for
discussion by experts on-air, whether they are correct or not. Simple
explanations can be good, but incorrect ones are never good.

Owen