In view of the above, for practical putposes, trying to get maximum
performance
out of the loaded radiator, it should be beneficial to have the same
diameter
of whip above the coil, rather than tapering whip?

That doesn't help much. What helps is a humongous top hat which does
help to equalize the current at the bottom of the coil and the current
at the top of the coil.

I know about the effect of hat, but I am refering to straight whip loaded
radiator and whip above the coil only. Forget the hats and ties.

Again:
One might deduct that if the current is diminishing towards the top, that
the
diameter of the radiator (RF resistance) could be tapered also. But since
the
RF current has to flow to the tip and then reflect and go back and interfere
with itself, we should make it uniform, where possible. (?)

Yuri

Cecil,

You appear to have some unique views of superposition and of standing waves.

In simple terms superposition says that one can combine two inputs, and
the combined output is equal to the sum of the individual outputs. Not
all systems exhibit superposition, of course, but I believe the
elementary antennas considered here do indeed follow the principle of
superposition with regard to current.

Why do you believe the "net" current somehow has different properties
than simply the sum of the two component traveling current waves? You
use the term "artifact", as if the net current is inconsequential or
even incorrect. Does superposition break down? Distributed network vs.
DC or AC model is not an issue, since the superposition must be
performed independently at each point in the region of interest.

(You seem to like to use "net", but "total" or "algebraic sum" mean the
same thing. I am not interested in any argument about performing the
vector math correctly. That must be assumed.)

Standing waves are not static. The current may not "flow", whatever that
means, but there is certainly real non-zero current at every point
except the exact nodes of the standing wave. If you prefer, the standing
wave current oscillates rather than flows, but that is of no special
importance here.

Why do you believe standing waves are somehow inferior to traveling waves?

(This message is absolutely serious. No tricks or trolling. If you want
to play word games, see ya later.)

73,
Gene
W4SZ


Cecil Moore wrote:


There is forward current flowing into the bottom of the coil and out
the top. There is reflected current flowing into the top of the coil
and out the bottom. The net current is a standing current wave. If we,
as Kraus suggests, assume that the forward current equals the reflected
current (relatively small error in doing so) then there is zero net current
flowing in and out of the coil. The standing wave current is, well, just
standing there and is not "going" anywhere.

The gross error that a lot of people are making is that standing
wave current flows. If the forward and reflected currents are equal,
as Kraus assumes for purpose of discussion, then there is zero net
current flow through the coil. Yet, net current is what everyone
is measuring. What they are actually measuring is the value of
the standing wave current at each end of the coil and it is not
flowing. It is only an artifact of the superposition of the two
waves that are flowing.

Gene Fuller wrote:
Why do you believe the "net" current somehow has different properties
than simply the sum of the two component traveling current waves?

Because the net current is a *STANDING WAVE* made up of equal magnitudes
of current flowing in opposite directions. That makes the net current
zero, Gene. Standing wave current doesn't flow. The RMS value stands still.
Standing waves are only an artifact of the superposition process. Everything
that needs to be known involves the two traveling waves that cause the
standing wave. Asserting that standing waves flow into the bottom of a
loading coil and out the top shows a complete ignorance of how standing
wave antennas really work. After that false premise, none of the
associated conclusions are valid.

Standing waves are not static.

The RMS value of a standing wave at any point is indeed static.

The current may not "flow", whatever that
means, but there is certainly real non-zero current at every point
except the exact nodes of the standing wave. If you prefer, the standing
wave current oscillates rather than flows, but that is of no special
importance here.

It is of infinite importance. If the standing wave current oscillates in
place, it doesn't flow through the coil. W8JI says it flows into the bottom
of the coil and out the top. Nothing could be farther from the facts of physics.

Why do you believe standing waves are somehow inferior to traveling waves?

Standing waves are an artifact of the superposition of two traveling waves.
Standing waves have a constant differing RMS value at every point on the
transmission line. Traveling waves travel and have the same RMS value all
up and down a lossless transmission line. What is it about that concept
that you don't understand?
--
73, Cecil http://www.qsl.net/w5dxp


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Cecil,

Thanks.

I thought I understood the situation. Now I am certain.

Bye. :-)

73,
Gene
W4SZ

Cecil Moore wrote:
Gene Fuller wrote:

Why do you believe the "net" current somehow has different properties
than simply the sum of the two component traveling current waves?


Because the net current is a *STANDING WAVE* made up of equal magnitudes
of current flowing in opposite directions. That makes the net current
zero, Gene. Standing wave current doesn't flow. The RMS value stands still.
Standing waves are only an artifact of the superposition process.
Everything
that needs to be known involves the two traveling waves that cause the
standing wave. Asserting that standing waves flow into the bottom of a
loading coil and out the top shows a complete ignorance of how standing
wave antennas really work. After that false premise, none of the
associated conclusions are valid.

Standing waves are not static.


The RMS value of a standing wave at any point is indeed static.

The current may not "flow", whatever that means, but there is
certainly real non-zero current at every point except the exact nodes
of the standing wave. If you prefer, the standing wave current
oscillates rather than flows, but that is of no special importance here.


It is of infinite importance. If the standing wave current oscillates in
place, it doesn't flow through the coil. W8JI says it flows into the bottom
of the coil and out the top. Nothing could be farther from the facts of
physics.

Why do you believe standing waves are somehow inferior to traveling
waves?


Standing waves are an artifact of the superposition of two traveling waves.
Standing waves have a constant differing RMS value at every point on the
transmission line. Traveling waves travel and have the same RMS value all
up and down a lossless transmission line. What is it about that concept
that you don't understand?

Gene Fuller wrote:
I thought I understood the situation. Now I am certain.

Hopefully, we can lay this thing to rest soon. The forward current
flows into the bottom of the coil and out the top. The reflected
current flows into the top of the coil and out the bottom. Those
two currents are very close to being equal magnitudes but their
phases are rotating in opposite directions. That is not a job
for the lumped circuit model. That's a job for the distributed
network model, something that you guys seem to have first ignored
and later tried to sweep under the rug.
--
73, Cecil http://www.qsl.net/w5dxp


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Gene, W4SZ wrote:
"Standing waves are not static."

Incredible!

My "American College dictionary" defines "standing wave": "a
distribution of wave displacements , such that the distribution in space
is periodic, with fixed maximum and minimum points, with the maxima
occuring everywhere at the same time, as in vibration of strings,
electric potentials, acoustic pressures, etc."

Note the word "fixed" in the definition. That`s a synonym for "static".

For how this applies to antennas and transmission lines, see page 177 of
Kraus` "Antennas", third edition, Figure 6-7. Notice that current
reverses 1/2-wavelength back from the antenna`s open-circuit endjust as
it does in the case of the open-circuit transmission-line, as shown by
Terman on page 92 of "Electronic and Radio Engineering", 1955 edition,
and on page 94 in FiG. 4-5 (a). This all starts at the reflection point
and progresses the same regardless of the length of the antenna or
transmission-line. It is due to superposition of the forward and
reflected waves, just as Cecil maintains.

Advice: Never argue with Kraus and Terman.

Best regards, Richard Harrison, KB5WZI

Richard,

I am quite familiar with standing waves, thank you. I have no
disagreements with Terman, Kraus, Balanis, or any other legitimate experts.

You can reread what I said, if you care to understand, rather than pick
a sentence out of context.

73,
Gene
W4SZ



Richard Harrison wrote:
Gene, W4SZ wrote:
"Standing waves are not static."

Incredible!

My "American College dictionary" defines "standing wave": "a
distribution of wave displacements , such that the distribution in space
is periodic, with fixed maximum and minimum points, with the maxima
occuring everywhere at the same time, as in vibration of strings,
electric potentials, acoustic pressures, etc."

Note the word "fixed" in the definition. That`s a synonym for "static".

For how this applies to antennas and transmission lines, see page 177 of
Kraus` "Antennas", third edition, Figure 6-7. Notice that current
reverses 1/2-wavelength back from the antenna`s open-circuit endjust as
it does in the case of the open-circuit transmission-line, as shown by
Terman on page 92 of "Electronic and Radio Engineering", 1955 edition,
and on page 94 in FiG. 4-5 (a). This all starts at the reflection point
and progresses the same regardless of the length of the antenna or
transmission-line. It is due to superposition of the forward and
reflected waves, just as Cecil maintains.

Advice: Never argue with Kraus and Terman.

Best regards, Richard Harrison, KB5WZI

Gene Fuller wrote:
I am quite familiar with standing waves, thank you. I have no
disagreements with Terman, Kraus, Balanis, or any other legitimate experts.

Question is: Why do you promote W8JI's stuff when it is quite obvious
that he is NOT familiar with standing waves. If he were familiar with
standing waves, he wouldn't be asserting that net standing wave current
flows into the bottom of the loading coil and out the top of the loading
coil. Are you absolutely sure that you want to promote the alleged
"information" on W8JI's web page as absolute fact? If he is so right
and so capable of defending his assertions, why isn't he here right
now? (Trying to get W8JI to follow me down the Primrose Path :-) as
he did when he asserted that "differential" effects are "completely
unrelated" to "common mode" effects.)
--
73, Cecil, W5DXP

Gene Fuller wrote:
I am quite familiar with standing waves, thank you. I have no
disagreements with Terman, Kraus, Balanis, or any other legitimate experts.

What I am still not understanding, is since the exponential equations
for voltage and current in a transmission line are identical except
for the Z0 term, how can something happen to the current without
the same thing happening to the voltage at the same time? How can
something happen to the voltage without also happening to the current
at the same time? In a matched system, the voltage and current arrives
at the load at exactly the same time attenuated by exactly the same
amount. But that voltage didn't flow and that current didn't drop???
--
73, Cecil, W5DXP

"Reg Edwards" wrote in message
...
Fact 1.

Any loading coil of finite length contributes towards to the total
radiation.

NEWSFLASH - there's no such thing as a perfect inductor. Amazing!

Fact 2.

The input and output currents of a loading coil of finite length are always
different from each other.

A natural consequence of fact #1.

Fact 3.

The radiation pattern of a short vertical is fixed and remains independent
of the location/height of the loading coil.

Not so, precisely because said inductor cannot be perfect. HOWEVER, the
difference is neglegible and probably immeasureable.

Fact 4.

Computer programs do not tell gospel truths. They are at least as
unreliable as their human programmers.

Ahh, but at least they are *consistantly* unreliable in predictable ways,
which is more than can be said for humans.

----
Reg.