Richard Harrison wrote:

Cecil, W5DXP wrote:
"That`s where you are wrong."

This argument has evoked plain statements, i.e., "When waves cease to
exist, they are forced to give up their intrinsic energy." And, "Waves
don`t cease to exist."

The statements need qualifications. Perhaps waves "cancel" without
ceasing to exist.

In the case we've been discussing the waves in fact never exist, except
on paper. This is because, for example, V3 and V4 cancel at the very
point at which they would begin to propagate. Cancellation precludes
their existance because they cancel for any time element (after the
transient period) and for every spacial element one can enter into the
equation. Contrary to what has been suggested, they do not first appear
and then subsequently disappear. Waves cannot just "cease to exist" for
the very same reason that energy cannot cease to exist.

It may be somewhat easier to see this when we consider that each
boundary can be viewed as a radiator, or re-radiator. When a wave
impinges upon it, the boundary conditions and the nature of the incident
wave determine how waves will be re-radiated from it. With a wave
impinging upon the boundary from one direction only, we would have one
outcome. With two or more waves impinging upon the boundary, we may
have a different outcome.

73, Jim AC6XG

(Dr. Slick) wrote in message . com...
(Art Unwin KB9MZ) wrote in message om...


Slick

Dr Slick,
Way back in this thread you alluded to antennas as being
transformers. The more I think about that statement the more I see
it as being fact. Anything that involved coupling which all
antennas do can be drawn as a transformer !
Since the thread migrated all over the place did you feel that
the group agreed with that position?
Regards
Art


Some have emailed me personally, and we have pretty much agreed on
these two points(even Roy agreed with these, if you read his posts
here):


1. Two antennas (also called transducers) placed close together
actually can be considered a transformer, albeit a very inefficient
one.

Humm...By antenna I assume it also means a radiator. This would
suggest
that a stagger tuned radiators would fall into the catagory discussed
above.
Now I have a problem with that statement, because I very much see it
as a transformer which is VERY efficient and not as you stated "albiet
a very inefficient one".
Can you explain to me how a stagger tuned antenna migrate into
inefficient radiators?
Seems to me that Thevenin's theorem would show this as being
incorrect !

-----
snip



Slick

Regards
Art

Jim Kelley wrote:
Waves cannot just "cease to exist" for
the very same reason that energy cannot cease to exist.

More bafflegab. An RF wave ceases to exist when it is dissipated
in a dummy load. The energy cannot cease to exist and turns to
heat but the RF wave, in a perfect dummy load, ceases to exist.
Heat is not RF. A light wave incident upon a perfect flat black
plane ceases to exist. The light waves that haven't exited the
room you are in when you turn off the light cease to exist. Some
light waves falling upon plants cease to exist in the process of
photosynthesis.

From _Optics_, by Hecht: "Unlike ordinary objects, photons cannot
be seen directly; what is known of them comes from observing the
results of their being either created or annihilated."

When photons are created, their wave function starts. When photons
are annihilated, their wave function ceases to exist. There is no
such thing as preservation of photons. You really need to get
yourself a better physics book.

EM waves cease to exist all the time but the energy in those waves
cannot be destroyed.
--
73, Cecil http://www.qsl.net/w5dxp



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Yeah, you've got me pegged, all right -- tireless defender of ham
radio's sacred cows. Perceptive of you. But we can all be thankful we've
got you to keep reminding us hams just how ignorant we, worshipping our
superstitious lore, are, compared to true professionals like you.

If only we could just come up an impedor for this.

Roy Lewallen, W7EL

W5DXP wrote:
Dave Shrader wrote:

Roy, you've been getting blamed for everything lately.
Now we can blame you for the new thread ... you started it! grin


Roy doesn't seem to appreciate me making hamburger out of ham radio's
sacred cows. :-) I actually enjoy the T-Bones best of all.

(Art Unwin KB9MZ) wrote in message m...

1. Two antennas (also called transducers) placed close together
actually can be considered a transformer, albeit a very inefficient
one.

Humm...By antenna I assume it also means a radiator. This would
suggest
that a stagger tuned radiators would fall into the catagory discussed
above.
Now I have a problem with that statement, because I very much see it
as a transformer which is VERY efficient and not as you stated "albiet
a very inefficient one".
Can you explain to me how a stagger tuned antenna migrate into
inefficient radiators?
Seems to me that Thevenin's theorem would show this as being
incorrect !



Well, two identical antennas spaced a few wavelengths apart can
be considered a transformer, but very inefficient compared to a "real"
transformer with identical primary and secondary turns, with an
appropriate toroid core. This would be because the core material will
increase the magnetic flux density, and will increase the coupling
between the two windings/transducers.

Point is, the farther apart the antennas are, the less efficient
of a "transformer" they will be.

I'm not familiar with stagger tuned antennas, although the name
would suggest that it is tuned for multiple resonances, so that the
antenna will be broadband.



Slick

I hope you'll pardon me for amplifying this a little.

If you put X watts into the primary of a transformer and extract Y watts
from the secondary, the efficiency is Y/X by definition.

If you put X watts into one antenna and extract Y watts from an antenna
coupled to it, and measure the efficiency of the "transformer" the same
way as you did the conventional transformer, you'll find it has lousy
efficiency. Why? Because a goodly fraction of the power you applied to
the "primary" antenna never gets to the "secondary" antenna because it's
radiated instead. As far as the "secondary" is concerned, it might as
well have been converted to heat.

If you look at the impedance of the "primary" antenna, you'll find an
excess of resistance -- just enough, in fact, to account for the "lost"
(radiated) power.

This isn't a statement about how well coupled antennas function as
antennas, whose purpose is to radiate after all. It's a statement about
how well they function as a transformer. Poorly.

Roy Lewallen, W7EL

Dr. Slick wrote:
(Art Unwin KB9MZ) wrote in message m...

1. Two antennas (also called transducers) placed close together
actually can be considered a transformer, albeit a very inefficient
one.

Humm...By antenna I assume it also means a radiator. This would
suggest
that a stagger tuned radiators would fall into the catagory discussed
above.
Now I have a problem with that statement, because I very much see it
as a transformer which is VERY efficient and not as you stated "albiet
a very inefficient one".
Can you explain to me how a stagger tuned antenna migrate into
inefficient radiators?
Seems to me that Thevenin's theorem would show this as being
incorrect !




Well, two identical antennas spaced a few wavelengths apart can
be considered a transformer, but very inefficient compared to a "real"
transformer with identical primary and secondary turns, with an
appropriate toroid core. This would be because the core material will
increase the magnetic flux density, and will increase the coupling
between the two windings/transducers.

Point is, the farther apart the antennas are, the less efficient
of a "transformer" they will be.

I'm not familiar with stagger tuned antennas, although the name
would suggest that it is tuned for multiple resonances, so that the
antenna will be broadband.



Slick

Roy Lewallen wrote in message ...
I hope you'll pardon me for amplifying this a little.

If you put X watts into the primary of a transformer and extract Y watts
from the secondary, the efficiency is Y/X by definition.

Yes Roy. The specifics of what is being discussed is all important
when looking at answers as well as what terms are being used to
measure 'efficiency' and to what ends.
As you are surely awawe I too look at antennas as transformers or
coupled circuits and thus the primary contributes very much in its own
way as far as radiation as does the secondary. Thus 'efficiency' as a
criteria of 'value'
is all important when using it as a term since as you point out it is
a ratio of two terms both of which have to be made very clear for the
term efficiency to be made clear
Thus in stagger tuning it is important to define your requirements in
terms of bandwidth (dual frequency radiation) or max gain ( dual
radiators on the same frequency),the above bearing little difference
to old time receiver designwith multiple I.F. cans. It is in this
areana that I view stagger tuning or coupling
as being efficient in charactor. If I am incorrect in the above
assumptions I would welcome any correction from those well versed
inthe field.
Best regards
Art


If you put X watts into one antenna and extract Y watts from an antenna
coupled to it, and measure the efficiency of the "transformer" the same
way as you did the conventional transformer, you'll find it has lousy
efficiency. Why? Because a goodly fraction of the power you applied to
the "primary" antenna never gets to the "secondary" antenna because it's
radiated instead. As far as the "secondary" is concerned, it might as
well have been converted to heat.

If you look at the impedance of the "primary" antenna, you'll find an
excess of resistance -- just enough, in fact, to account for the "lost"
(radiated) power.

This isn't a statement about how well coupled antennas function as
antennas, whose purpose is to radiate after all. It's a statement about
how well they function as a transformer. Poorly.

Roy Lewallen, W7EL

Dr. Slick wrote:
(Art Unwin KB9MZ) wrote in message m...

1. Two antennas (also called transducers) placed close together
actually can be considered a transformer, albeit a very inefficient
one.

Humm...By antenna I assume it also means a radiator. This would
suggest
that a stagger tuned radiators would fall into the catagory discussed
above.
Now I have a problem with that statement, because I very much see it
as a transformer which is VERY efficient and not as you stated "albiet
a very inefficient one".
Can you explain to me how a stagger tuned antenna migrate into
inefficient radiators?
Seems to me that Thevenin's theorem would show this as being
incorrect !




Well, two identical antennas spaced a few wavelengths apart can
be considered a transformer, but very inefficient compared to a "real"
transformer with identical primary and secondary turns, with an
appropriate toroid core. This would be because the core material will
increase the magnetic flux density, and will increase the coupling
between the two windings/transducers.

Point is, the farther apart the antennas are, the less efficient
of a "transformer" they will be.

I'm not familiar with stagger tuned antennas, although the name
would suggest that it is tuned for multiple resonances, so that the
antenna will be broadband.



Slick

"W5DXP" wrote in message
...
There's another one of your contradictions. "Cancellation (of two waves)
precludes their existance ..."??? How can two waves cancel if they never
existed? Once again, you are confusing cause and effect. You are asserting
an effect caused by itself. That won't fly.

:-) Sorry, Cecil. It's a fact.

Cancellation
requires at least two waves.

:-) Cancellation requires zero waves You can't have it both ways..

Maxwell's equations contain partial differentials
for dx, dy, dz, and dt.

Yes they do, and for any set of finite values of those variables for two
superposed functions of equal amplitude an opposite phase, the solution is
zero. You can write the functions for the two waves and prove they cannot
exist.


You seem incapable of conceiving of canceling wavefronts that exist for
only
a dt of time.

Since the functions cancel during that dt of time as well as any other
length of time, you're right.
..
I, OTOH, am completely incapable of conceiving of the cancellation
of two waves that never existed.

Not my problem.

73, ac6xg

W5DXP wrote:

They say that reflected traveling waves disappear when steady-state is
reached. I say such a disappearing act would have to be magic.

Just hours earlier you were flinging insults at me for disputing your
claim that reflected traveling waves disappear in the steady state.

ac6xg

Jim Kelley wrote:
"W5DXP" wrote:
There's another one of your contradictions. "Cancellation (of two waves)
precludes their existance ..."??? How can two waves cancel if they never
existed? Once again, you are confusing cause and effect. You are asserting
an effect caused by itself. That won't fly.

:-) Sorry, Cecil. It's a fact.

It may be a truth, but only in your mind. It is certainly not a fact.

Cancellation requires at least two waves.

:-) Cancellation requires zero waves You can't have it both ways..

Cancellation can occur between zero waves? That's just bafflegab.
If zero waves exist, wave cancellation is impossible.

Maxwell's equations contain partial differentials
for dx, dy, dz, and dt.

Yes they do, and for any set of finite values of those variables for two
superposed functions of equal amplitude an opposite phase, the solution is
zero. You can write the functions for the two waves and prove they cannot
exist.

You are again confusing cause and effect. The solution is zero in only one
direction in a transmission line and we already know that. The principle of
conservation of energy dictates that the solution cannot be zero in the
opposite direction. The two rearward-traveling wavefronts cancel each other.
Their intrinsic energy components cannot be canceled. Therefore, that intrinsic
energy changes directions and joins the forward wave. It is all explained on
the Melles-Griot web page.

You seem incapable of conceiving of canceling wavefronts that exist for
only a dt of time.

Since the functions cancel during that dt of time as well as any other
length of time, you're right.

Your inability to conceptualize is your problem, not mine. My dog shares
that mental problem with you but I love her anyway.

I, OTOH, am completely incapable of conceiving of the cancellation
of two waves that never existed.

Not my problem.

Certainly not mine. Do you really expect any rational person to accept your
assertion that wave cancellation occurs between wavefronts that never existed?
Do you also believe that marriages occur between men and women who never existed?
--
73, Cecil http://www.qsl.net/w5dxp



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