On 19 Oct, 09:04, (Richard Harrison) wrote:
Art wrote:

"And "end effect" is the confusion created at the top of the radiator."
I was carrying on the train of thought of the poster, I have made it
quite clear what my thoughts are.

When the signal arrives at the open circuit end of the antenna, current
can not continue its forward flow. It abruptly stops, no longer
producing a magnetic field.

Who says so? I suspect that in the recognition of a measurement
problem
you theorised what might have , could have etc to match your faulty
logic.


..


Energy from the magnetic field is converted to energy in the electric
field for an instant (Cecil`s famous conservation of energy). This
produces an insreased voltage at the open circuit end. This incresed
voltage has more capacitive effect, akin to the "Miller effect" caused
by the higher signal voltage on the plate of an amplifier vacuum tube
than on its grid.

All this is faulty logic manufactured to suit your intelligence.
Radiation is a function of the release of energy from capacitance and
inductance
during a cycle i.e. a parallel circuit called a "tank circuit: which
can also
be seen as a loss less system ala a pendulum.
This goes back to what I say about books. Anybody can write one. It is
up
to the reader to follow the dots of logic displayed to determine
agreement
not to swallow it and memorise it.





On a transmission line or on an antenna system, we used to call this
capacitive action the "Ferranti effect"

Best regards, Richard Harrison, KB5WZI

Art wrote:
"Who says so?"

Many. It is commonly held opinion.

Frederick Emmons Terman writes on page 89 of his 1955 opus:

"When the load impedance is infinite, Eq. (4-14) shows that that the
coeficient of reflection will be 1 on an angle of 0. Under these
conditions the incident and reflected waves will have equal magnitudes
at the load, and the reflection will be such that the voltages of the
incident and reflected waves have the same phase. As a result, the
voltages of the two waves add mathematically so that at the load
E1=E2+EL/2.

Best regards, Richard Harrison, KB5WZI

On 19 Oct, 11:43, (Richard Harrison) wrote:
Art wrote:

"Who says so?"

Many. It is commonly held opinion.
Right, it is opinion not factual.
There is no proof what so ever that is what happens.
So you must also consider alernatives.
Current can go out into space which doesn't seem plausible
Current can flow inside the copper wire which is plausible

So now we have a measurement problem. How can we track
one path from the other or you come up with a reason
that it can't flow thru the center of copper



Frederick Emmons Terman writes on page 89 of his 1955 opus:

"When the load impedance is infinite,

WELL,WELL,WELL!

Probably true except for one thing.... THE LOAD IMPEDANCE IS NOT
INFINITE !
See what I mean about books. It is not a case of remembering what
somebody
said it is a case of connecting the dots with good logic that one
finds
unmistakable agreement.
Which brings up another point with respect to radiation about which
many admit is not known.
If the laws of Maxwell are in agreement with the extension of Gauss
which many say
of the latter is not correct then logic states we should remove
Maxwell.
Problem is that computor programs based on Maxwell laws also confirm
Gaussian law.
So now YOU connect the dots. Maxwell is correct? Computor programs
based on Maxwell
are correct. Computor programs confirm Gausses law extensions re
adding a time varying field.
Mathematics support Gaussian verification of Gaussion law, so
where is the logic of condemming Gaussian law and yet not condemming
all other laws?

Lesson: Use your own logic before referring what you read to memory
otherwise
you are just a member of the herd without a contribution of your own.
Just follow the arse of who goes before youand ignor the smell
Art


Eq. (4-14) shows that that the
coeficient of reflection will be 1 on an angle of 0. Under these
conditions the incident and reflected waves will have equal magnitudes
at the load, and the reflection will be such that the voltages of the
incident and reflected waves have the same phase. As a result, the
voltages of the two waves add mathematically so that at the load
E1=E2+EL/2.

Meaningless jabber since it is based on "infinite impedance" which is
in error.
thus the analysis is in error for the circumstances at hand.


Best regards, Richard Harrison, KB5WZI

Art wrote:
"THE LOAD IMPEDANCE IS NOT INFINITE!"

Relative to the impedance of a reasonable antenna. the impedance of the
atmosphere or the impedance of free-space is non-conductive.
When the signal following the conductive surface of an antenna reaches
its end of the conductive path, current reverses its direction of travel
of necessity.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote:
Relative to the impedance of a reasonable antenna. the impedance of the
atmosphere or the impedance of free-space is non-conductive.
When the signal following the conductive surface of an antenna reaches
its end of the conductive path, current reverses its direction of travel
of necessity.

Maybe better understood using visible EM waves.
When the medium's index of refraction changes,
reflections are the result. One can learn a
lot about EM wave reflection by looking in a
mirror. With some of the strange concepts about
EM reflected energy that exist on this newsgroup,
it is a wonder how the promoters of such concepts
can look themselves in the mirror. :-)
--
73, Cecil http://www.w5dxp.com

On 19 Oct, 14:31, Cecil Moore wrote:
Richard Harrison wrote:
Relative to the impedance of a reasonable antenna. the impedance of the
atmosphere or the impedance of free-space is non-conductive.
When the signal following the conductive surface of an antenna reaches
its end of the conductive path, current reverses its direction of travel
of necessity.

Maybe better understood using visible EM waves.
When the medium's index of refraction changes,
reflections are the result. One can learn a
lot about EM wave reflection by looking in a
mirror. With some of the strange concepts about
EM reflected energy that exist on this newsgroup,
it is a wonder how the promoters of such concepts
can look themselves in the mirror. :-)
--
73, Cecil http://www.w5dxp.com

Probably true. I wonder if they would continue
to argue if the 1/4 wave antenna was tubular or is
there another reason that the center of a radiator
is off limits to current flow.
Still you can't blame them if all they know comes
from the ARRL books. After all it is a hobby and in
the early days many did not have the opportunity
for a college education
Best regards
Art

Art wrote:
"Still you can`t blame them if all they know comes from the ARRL books.
After all it is a hobby and in the early days many did not have an
opportunity for a college education."

Despite Art`s disdain for amateurs, I`ve found solid information in the
"ARRL Antenna Book". Mine contains Characteristics of a lambda/4
monopole which includes: "The current in a lambda/4 monopole varies
practically sinusoidally (as is the case with a lambda/2 wire), and is
highest at the ground-plane connection. The RF voltage, however is
highest at the open (top) end and minimum at the ground-plane
connection." The reason for this is already given in this thread.

Best regards, Richard Harrison, KB5WZI

On 19 Oct, 13:35, (Richard Harrison) wrote:
Art wrote:

"THE LOAD IMPEDANCE IS NOT INFINITE!"

Relative to the impedance of a reasonable antenna. the impedance of the
atmosphere or the impedance of free-space is non-conductive.
When the signal following the conductive surface of an antenna reaches
its end of the conductive path, current reverses its direction of travel
of necessity.

Best regards, Richard Harrison, KB5WZI

Keep to the discussion at hand. The route to free space was discarded
but there is another route available which you choose to ignore,
Well not you since you just quote from books without personal
voutching.
So let us say Terman chose to ignore or his secretary screwed up.
Unless ofcourse you have dotted the I's and T,s for yourself
and can personally confirm the corectness of what you have quoted.
So pray tell me, what is the impedance of current flow on the inside
of a tube
or down the center of a solid conductor assuming there is no 10 foot
fence placed at the top end of a fractional wave length antenna.
We will leave the lights on for the current to see the inside of the
tube

I mistyped: E1=E2+EL/2

The + sign should have been an = sign. I didn`t remove my finger from
the dhift register in time and the wrong character emerged (a + instead
of the = sign). I am sorry. It should have read:

E1=E2=EL/2 because EL is the sum of E1 and E2 which are equal.

Best regards, Richard Harrison, KB5WZI