On Feb 25, 11:07*am, K1TTT wrote:
sorry, 1846, even older than i thought... aether, sea of electrons,
rare plasma, none are necessary for electromagnetic waves.

On the contrary, a quantum soup is indeed required. If photons could
propagate without a structure, they could exit the universe but they,
like us, are trapped and confined to the universe.
--
73, Cecil, w5dxp.com

Hello Richard,

I agree with you that several statements on Norbert's site will not
hold when scientifically reviewed. However I think the way you
respond will likely not result in better statements.

As the name of the newsgroup indicates; this is a radio amateur group
and Norbert site starts with "Dutch amateur radio station". This may
require another approach then you should use in a professional
environment. If you prefer that, Edaboard.com (just an example) is a
more suitable place.

Now the result is a professional reaction of Norbert:

Thank you for the explanations. I have not had the intention to start a
scientific discussion here on this subject. To me it is a hobby. With my
homepage I just want to share some of my experience with magnetic loop
antennas, just like many other radio amateurs do. And of course I am willing
to reply to reactions from readers. But I will not further discuss about
scientifically details.

Thank you.

Best Regards

73,

Norbert PA7NR

Because of rain, I had to stop some activity so I took a pocket
calculator, some of my own course material and a used envelope within
reach.

A loop with diameter = 1.27m (4m perimeter), made from 20mm (diameter)
copper has an inductance of about 3.4 uH (reactance of about 77 Ohm at
3.6 MHz).

Radiation resistance (no coupling with other objects) will be about 1
mOhm.

AC copper resistance due to skin effect will be about 30 mOhm (based
on uniform current distribution over the circumference of the
tubing).

Q factor should be in the range of 2500
Radiation efficiency will be about 3%
Directivity is 1.5
Voltage between ends (100W input): 6.3 kVp.
Current through loop about 82 Ap

A half wave dipole will have about 1kVp at each end (depends on
conductor thickness).

Effective area of antenna will be about 23 sqm (in free space).

1Vrms incident plane wave field (2.65mW/sqm) will result in about 61mW
output power (about 150Vp across the tuning capacitor).

You probably know that measuring a lower Q factor may result in less
overall efficiency (coupling to dissipative objects) or higher overall
efficiency (coupling to metallic conductors that reradiate).

With kind regards,


Wim
PA3DJS
www.tetech.nl
without abc, PM will reach me very likely

Uzytkownik "Cecil Moore" napisal w wiadomosci
...
On Feb 25, 6:54 am, K1TTT wrote:
i am referring to a theory from around 1880 that had a sea of
electrons as the aether for propagating electromagnetic waves.

Change "sea of electrons" to "quantum soup" and the aether theory is
alive and well. Even photons need a structure through which to
propagate.

Waves need medium to propagate. Some scientists prefer mystery aether some
ordinary matter. Faraday and Ludwig Lorenz were sure that in space is enough
mater and no mystery aether. Now everybody know that in space is ISM (rare
plasma + dust). It is ordinary matter (electrons, ions and dust). But radio
waves will be always the aether waves. So we also can say that aether
consists of ordinary particles.
S*
--

"Cecil Moore" napisal w wiadomosci
...
On Feb 25, 3:11 am, "Szczepan Bialek" wrote:
Radio wavesare are radiated from the nodes. In dipole the nodes are
created
by reflected wave (waves in the opposite direction). In the loop the waves
travel in oppsite direction and create the nodes also.

In a dipole, the reflections are naturally from the impedance
discontinuity at the open ends of the dipole. In a loop, the
reflections on the antenna are from the impedance discontinuity at the
feedpoint.

I do not understand. A loop can be made of wires without any discontinuity
at the feedpoint. Pulses send from supply must collide in the loop. The
nodes appear like in a dipole but without reflections. For what you need
reflections in a loop?
S*

On Feb 26, 12:21*pm, "Szczepan Bialek" wrote:
So we also can say that aether
consists of ordinary particles.

It depends upon how one defines "ordinary". The structure of free
space has existed since the big bang but man has only recently
discovered the structure and is still somewhat ignorant of its
configuration and characteristics. There is some evidence that the
structure of space in which ordinary non-dark matter and non-dark
energy exists, is made up of dark matter and dark energy.

I do not understand.

A loop, like a dipole, is a standing wave antenna with a
characteristic impedance in the few hundred ohms, e.g. 600 ohms. The
reflections on a standing wave antenna have to originate from an
impedance discontinuity. The feedpoint impedance of a standing wave
antenna is Zfp = (Vfor + Vref)/(Ifor + Iref) where phasor math is
used. Let's assume that the feedpoint impedance is 100+j0 ohms and the
antenna is being fed with Z0=100 ohm feedline. There are no
reflections on the feedline which means a Z0-match to 100 ohms exists
at the antenna feedpoint. Assume the characteristic impedance of the
antenna wire over ground is 600 ohms. The 600 ohm to 100 ohm impedance
discontinuity at the feedpoint creates a reflection coefficient of
0.7. That's where the reflections on the standing wave loop antenna
are coming from. One reason the feedpoint of a resonant loop is higher
than for a 1/2WL dipole is that the reflection coefficient for the
loop is 0.7 while the reflection coefficient for a dipole is obviously
1.0 at the ends of the dipole.

The concept may be easier to understand using a rhombic example. A
terminated rhombic is terminated in the characteristic impedance of
the antenna wire above ground, e.g. 600 ohms, which eliminates
reflections on the antenna and turns it into a traveling wave antenna
where the feedpoint impedance of the antenna is equal to the
characteristic impedance of the antenna over a wide frequency range,
i.e. Zfp = Vfor/Ifor, independent of frequency.

Removing the termination turns the rhombic antenna into a standing
wave antenna and the feedpoint impedance becomes Zfp = (Vfor + Vref)/
(Ifor + Iref), i.e. the feedpoint impedance is frequency dependent
like other standing wave antennas.
--
73, Cecil, w5dxp.com

On Sat, 26 Feb 2011 07:30:00 -0800 (PST), Wimpie
wrote:

Hi Wimpie,

This may
require another approach then you should use in a professional
environment. If you prefer that, Edaboard.com (just an example) is a
more suitable place.

Now the result is a professional reaction of Norbert:

Curious combination of conflicting sentiments, there. What is
suitable, and how should we recognize it?

Radiation resistance (no coupling with other objects) will be about 1
mOhm.

There are many source for computation, I chose one that closely agrees
with several at hand. Perhaps I made an entry error, so I will take
the opportunity to examine that possibility he
Rr = 80 · pi² · (dl/lambda)²
80 · 9.87 · (2/80)²
790 · (0.025)²
790 · 0.0006
0.49 Ohm

Of course, the possibility of mis-entry remains, and cross checking is
helpful given an in dependant validation. If I examine my text
further it uses as an example a smaller loop at a lower frequency
dl = 1m
F = 1MHz
(lambda = 300)
resulting in
Rr = 0.0084 Ohm
which is roughly 10 times your computed radiation resistance for a
larger loop at a smaller wavelength.

Now, having said that, and examining my text for further possibilities
of error, I find that, yes, I made an error. My computation was based
for an electric dipole, not a loop. Let us examine the Rr for a loop
from the equation from the same source:
Rr = 320 · pi^6 · (r/Lambda)^4
320 · 961 · (1/80)^4
307,645 · 2.44^-8
0.0075 Ohm
This, too, is very different from your calculation, but certainly that
error is eclipsed by my own first reckoning. However, what does this
say about efficiency based upon the original design (but computed for
another)?

However, I did first ask Norbert for the equation used and the
parameters entered. Testing those results did not appear to be
appealing in the face of contradicting testimonial. It should come as
no surprise that many testimonials are tested here. Testimonials
stand or fall in such tests, and those tests are retested (as has
given rise to this and your response).

Curiously we entered into this with how the loop has superior
qualities over the standard dipole, and then the same loop is cited as
being very inefficient. How such contradictions are held within the
space of a short thread is certainly a denial of engineering
professionalism, but denial is not the standard of merit that is
typically lauded in this forum. A hearty defense of wounded ego
raises suspicion even further.

One consequence of that demurral brings us to a rather remarkable
insight in comparing the radiation resistance of the electric dipole
to the loop within the same spread of the loop (and in certainly a
smaller volume of space). The electric dipole enjoys 60 times more
radiation resistance that certainly impacts efficiency to the same
degree. This, of course, presumes no further errors in computation or
application.

73's
Richard Clark, KB7QHC

On 2/27/2011 11:03 PM, Richard Clark wrote:
On Sat, 26 Feb 2011 07:30:00 -0800 (PST),
wrote:

Hi Wimpie,

This may
require another approach then you should use in a professional
environment. If you prefer that, Edaboard.com (just an example) is a
more suitable place.

Now the result is a professional reaction of Norbert:

Curious combination of conflicting sentiments, there. What is
suitable, and how should we recognize it?

Radiation resistance (no coupling with other objects) will be about 1
mOhm.

There are many source for computation, I chose one that closely agrees
with several at hand. Perhaps I made an entry error, so I will take
the opportunity to examine that possibility he
Rr = 80 · pi² · (dl/lambda)²
80 · 9.87 · (2/80)²
790 · (0.025)²
790 · 0.0006
0.49 Ohm

Of course, the possibility of mis-entry remains, and cross checking is
helpful given an in dependant validation. If I examine my text
further it uses as an example a smaller loop at a lower frequency
dl = 1m
F = 1MHz
(lambda = 300)
resulting in
Rr = 0.0084 Ohm
which is roughly 10 times your computed radiation resistance for a
larger loop at a smaller wavelength.

Now, having said that, and examining my text for further possibilities
of error, I find that, yes, I made an error. My computation was based
for an electric dipole, not a loop. Let us examine the Rr for a loop
from the equation from the same source:
Rr = 320 · pi^6 · (r/Lambda)^4
320 · 961 · (1/80)^4
307,645 · 2.44^-8
0.0075 Ohm
This, too, is very different from your calculation, but certainly that
error is eclipsed by my own first reckoning. However, what does this
say about efficiency based upon the original design (but computed for
another)?

However, I did first ask Norbert for the equation used and the
parameters entered. Testing those results did not appear to be
appealing in the face of contradicting testimonial. It should come as
no surprise that many testimonials are tested here. Testimonials
stand or fall in such tests, and those tests are retested (as has
given rise to this and your response).

Curiously we entered into this with how the loop has superior
qualities over the standard dipole, and then the same loop is cited as
being very inefficient. How such contradictions are held within the
space of a short thread is certainly a denial of engineering
professionalism, but denial is not the standard of merit that is
typically lauded in this forum. A hearty defense of wounded ego
raises suspicion even further.

One consequence of that demurral brings us to a rather remarkable
insight in comparing the radiation resistance of the electric dipole
to the loop within the same spread of the loop (and in certainly a
smaller volume of space). The electric dipole enjoys 60 times more
radiation resistance that certainly impacts efficiency to the same
degree. This, of course, presumes no further errors in computation or
application.

73's
Richard Clark, KB7QHC


Wimpie is right, Richard.

Please go back to your laboratory and speak to someone who understands
your dumb-ass dialect. Also, please don't discourage those who are
trying to contribute their experiences here. Try to be positive for a
change.

John

"Cecil Moore" napisal w wiadomosci
...
On Feb 26, 12:21 pm, "Szczepan Bialek" wrote:
So we also can say that aether
consists of ordinary particles.

It depends upon how one defines "ordinary". The structure of free
space has existed since the big bang but man has only recently
discovered the structure and is still somewhat ignorant of its
configuration and characteristics. There is some evidence that the
structure of space in which ordinary non-dark matter and non-dark
energy exists, is made up of dark matter and dark energy.

I prefer this: "It seems to be a natural consequence of our points of view
to assume that
the whole of space is filled with electrons and flying electric ions of all
kinds. We have assumed that each stellar system in evolutions throws off
electric corpuscles into space. It does not seem unreasonable therefore to
think that the greater part of the material masses in the universe is found,
not in the solar [sic] systems or nebulae, but in 'empty' space" (Birkeland
1913).
Thorndike (1930) noted that "it could scarcely have been believed that the
enormous gaps between the stars are completely void. Terrestrial aurorae are
not improbably excited by charged particles from the Sun emitted by the Sun.
If the millions of other stars are also ejecting ions, as is undoubtedly
true, no absolute vacuum can exist within the galaxy."



A loop antenna' is a radio antenna consisting of a loop of wire or other
conductor with its ends connected to a two-wire transmission line. They have
a radiation pattern similar to a dipole antenna"

I do not understand.

A loop, like a dipole, is a standing wave antenna with a
characteristic impedance in the few hundred ohms, e.g. 600 ohms. The
reflections on a standing wave antenna have to originate from an
impedance discontinuity. The feedpoint impedance of a standing wave
antenna is Zfp = (Vfor + Vref)/(Ifor + Iref) where phasor math is
used. Let's assume that the feedpoint impedance is 100+j0 ohms and the
antenna is being fed with Z0=100 ohm feedline. There are no
reflections on the feedline which means a Z0-match to 100 ohms exists
at the antenna feedpoint. Assume the characteristic impedance of the
antenna wire over ground is 600 ohms. The 600 ohm to 100 ohm impedance
discontinuity at the feedpoint creates a reflection coefficient of
0.7. That's where the reflections on the standing wave loop antenna
are coming from. One reason the feedpoint of a resonant loop is higher
than for a 1/2WL dipole is that the reflection coefficient for the
loop is 0.7 while the reflection coefficient for a dipole is obviously
1.0 at the ends of the dipole.

The concept may be easier to understand using a rhombic example. A
terminated rhombic is terminated in the characteristic impedance of
the antenna wire above ground, e.g. 600 ohms, which eliminates
reflections on the antenna and turns it into a traveling wave antenna
where the feedpoint impedance of the antenna is equal to the
characteristic impedance of the antenna over a wide frequency range,
i.e. Zfp = Vfor/Ifor, independent of frequency.

Removing the termination turns the rhombic antenna into a standing
wave antenna and the feedpoint impedance becomes Zfp = (Vfor + Vref)/
(Ifor + Iref), i.e. the feedpoint impedance is frequency dependent
like other standing wave antennas.

See: http://paws.kettering.edu/~drussell/Phys302/09.html

"Electromagnetic pulse in a coaxial cable reflects from a short circuit with
the opposite polarity (upside down)"

A loop is like a short circuit. What do a Electromagnetic pulse in a loop?
It simply travel trough the loop and looks like the "reflected with the
opposite polarity ". Why am I wrong and D. Russell is right?
S*
--

On Feb 28, 3:52*am, "Szczepan Bialek" wrote:
A loop is like a short circuit. What do a Electromagnetic pulse in a loop?
It simply travel *trough the loop and looks like the "reflected with the
opposite polarity ". Why am I wrong and D. Russell is right?

What you are missing is that the loop is an antenna, not a
transmission line. On a transmission line, the currents are
differential, i.e. 180 degrees out of phase and a short-circuit is
possible. At the antenna feedpoint the left differential current takes
a 90 degree turn to the left. The right differential current takes a
90 degree turn to the right. *That puts the antenna currents in
phase*, i.e. in common-mode, so a short circuit on an antenna 40 feet
in the air is not possible. The fields that are 180 degrees out of
phase no longer cancel because of the physical distance between them.

From the feedpoint of the antenna, there is no such thing as waves
launched in opposite directions on the wire *at the same time*. What
you are missing is there is no short-circuit half way around a loop
because there is no impedance discontinuity at that point. Forward
waves continue traveling forward and reflected waves continue to
travel backwards at that point because there is no impedance
discontinuity at that point. It takes an impedance discontinuity to
cause a reflection. Assuming a circular horizontal loop (for the sake
of conceptual simplicity) the only impedance discontinuity is at the
feedpoint.
--
73, Cecil, w5dxp.com

On Sun, 27 Feb 2011 23:14:34 -0600, John - KD5YI
wrote:

Wimpie is right, Richard.

I presume Wimpie can speak for himself. As he offered musings that
were done on the back of a handy envelope, there is every chance he is
not right. I offered a similar chance that I was not right either,
but I offered complete (two in fact) equations that no one has
disputed, and none have faulted for computation. I admitted a
misapplication of one - which also passed without comment.

Considering Wimpie's work was not done for the antenna under
consideration (the size of his being much smaller where radiation
resistance varies by the FOURTH POWER of size) - what does "right"
mean?

73's
Richard Clark, KB7QHC