Henry Kolesnik wrote:
"If I wanted to measure the difference between the two fields how would
I measure the electric field?"

If this is the radiation field, not the reactive field, it would make no
difference if you measured the electric field or the magnetic field, as
they contain the same quantity of energy. In fact, the energy is
identical as one field begets the other field. That`s "The Secret of
Propagation".

That does not mean the fieldfs can`t be separated. It is easy. Enclose
your loop in an effective Faraday screen. This screen prohibits
electrostatic coupling to the loop, but freely allows magnetic coupling.

Faraday screens are not rare. Nearly every medium wave broadcast station
uses a Faraday screen at every tower between the primary and secondary
of an air-core coupling transformer. Because, without the screen,
capacitive coupling to the tower would favor harmonics of the broadcast
frequency over its fundamental frequency and make compliance with FCC
rules difficult. The Faraday screen is also an excellent lightning
protector.

It`s just as easy to allow only capacitive coupling. Simply put a
circuit to be kept from magnetic coupling in an enclosure which is
completely enclosed in a metal structure (sealed like an expensive
signal generator except for one small hole). Use a capacitor through the
small hole to couple to the outside world. Only the electric field via
the capacitor will influence the circuit in the box.

R-F will not penetrate a metal shield, unless it`s special like the
sliced-up Faraday screen. Then, it`s only the magnetic field which
penetrates. Skin effect requires r-f to flow only on the surface of good
conductors to any appreciable depth.

Best regards, Richard Harrison, KB5WZI

Hank, and Richard, For a good explanation of this subject I always liked the
book: "Introduction to Electromagnetic Fields" by Paul and Nasar. The first
two chapters of mathematical review are excellent. I see barnesandnoble.com
has the 3rd edition, used, for as low as $66. John D. Kraus' book;
"Electromagnetics" is also a very good text.

73,

Frank

Isn't Kraus "Electromagnetics" a little heavy on the math for the
average Ham ??

Frank wrote:

Hank, and Richard, For a good explanation of this subject I always liked the
book: "Introduction to Electromagnetic Fields" by Paul and Nasar. The first
two chapters of mathematical review are excellent. I see barnesandnoble.com
has the 3rd edition, used, for as low as $66. John D. Kraus' book;
"Electromagnetics" is also a very good text.

73,

Frank

"Ham op" wrote in message
...
Isn't Kraus "Electromagnetics" a little heavy on the math for the average
Ham ??

I guess it depends on how interested they are. A good grounding in advanced
calculus is certainly a prequesit for either of those texts. Even
elementary calculus, combined with chapters 1 and 2, of Paul and Nasar,
should be sufficient.

73,

Frank


Frank wrote:

Hank, and Richard, For a good explanation of this subject I always liked
the book: "Introduction to Electromagnetic Fields" by Paul and Nasar.
The first two chapters of mathematical review are excellent. I see
barnesandnoble.com has the 3rd edition, used, for as low as $66. John D.
Kraus' book; "Electromagnetics" is also a very good text.

73,

Frank

Ham Op:

Yes, it is... mostly, people who are NOT gifted in explanations that the
"layman" can understand--gravitate to such extreme mathematics (and turn
them off, effectively silencing them).... let me give you my views...

.... it is somewhat obvious that when a wave sent forth from our antennas
encounters a metallic object that is close to resonate freq, and a very good
to EXCELLENT conductor, that a LARGE current flows in the metallic structure
encountered--what E and what H wave are then products are debatable (the
energy absorbed is re-radiated)--however--probably of a very different
nature than that of wave which encountered the metallic object in
question--and here is where this debate is ongoing... at an extreme is a
"tesla coil", ultimate voltage and virtually NO current (very minimal
current to generate the nice purple coronas)--yet an excellent transmitting
"antenna"--and that is ALL "E-wave." (well, mostly...)

Warmest regards,
John

"Ham op" wrote in message
...
Isn't Kraus "Electromagnetics" a little heavy on the math for the average
Ham ??

Frank wrote:

Hank, and Richard, For a good explanation of this subject I always liked
the book: "Introduction to Electromagnetic Fields" by Paul and Nasar.
The first two chapters of mathematical review are excellent. I see
barnesandnoble.com has the 3rd edition, used, for as low as $66. John D.
Kraus' book; "Electromagnetics" is also a very good text.

73,

Frank

"John Smith" wrote in message
...
Ham Op:

Yes, it is... mostly, people who are NOT gifted in explanations that the
"layman" can understand--gravitate to such extreme mathematics (and turn
them off, effectively silencing them).... let me give you my views...

I thought that my explanations were very non-mathematical, requiring only
minimal use of very simple calculations. My response was not complete as I
did not want to go overboard, but try to give very easy examples that could
be expanded on if any interest was shown. Perhaps you could be more
specific as to where I went wrong in my response. My mention of a couple of
textbooks was only to provide references for those interested in trying to
understand concepts in more detail. While it is true that some people are
capable of rigorous mathematical analysis, they cannot explain it in
non-mathematical terms. Those people, then, do not really understand their
subject. It is also true that such complex subjects cannot be fully
understood without in-depth math (Which is something I wish I had).
..
... it is somewhat obvious that when a wave sent forth from our antennas
encounters a metallic object that is close to resonate freq,

Not sure that resonance is important.
and a very good to EXCELLENT conductor, that a LARGE current flows in the
metallic structure encountered--

Current will flow in the surface.

what E and what H wave are then products are debatable (the energy
absorbed is re-radiated)--however--probably of a very different nature
than that of wave which encountered the metallic object in question--and
here is where this debate is ongoing...

If the conducting surface is perfect, no absorbtion takes place. The
reflected EM wave is planar, and identical to the incident plane wave --
with the exception of direction of propagation, and a phase reversal. A
(spatial) standing wave pattern is set up, and the analysis is identical to
that of a shorted transmission line.

at an extreme is a "tesla coil", ultimate voltage and virtually NO current
(very minimal current to generate the nice purple coronas)--yet an
excellent transmitting "antenna"--and that is ALL "E-wave." (well,
mostly...)

A Tesla coil is not an antenna, although some radiation will take place from
its conductors -- which will probably be damped sinusoidal pulses similar to
a spark transmitter. The radiation will not be all "E", but will have the
same E/H ratio of any radiated signal. i.e. E/H = 377 (ohms) in the far
field.

73,

Frank


Warmest regards,
John

"Ham op" wrote in message
...
Isn't Kraus "Electromagnetics" a little heavy on the math for the average
Ham ??

Frank wrote:

Hank, and Richard, For a good explanation of this subject I always liked
the book: "Introduction to Electromagnetic Fields" by Paul and Nasar.
The first two chapters of mathematical review are excellent. I see
barnesandnoble.com has the 3rd edition, used, for as low as $66. John
D. Kraus' book; "Electromagnetics" is also a very good text.

73,

Frank

A Tesla coil is not an antenna, although some radiation will take place
from its conductors -- which will probably be damped sinusoidal pulses
similar to a spark transmitter. The radiation will not be all "E", but
will have the same E/H ratio of any radiated signal. i.e. E/H = 377
(ohms) in the far field.

73,

Frank

Just checked http://home.wtal.de/herbs_teslapage/theory.html The Tesla coil
is a spark transmitter without an antenna connected.

Frank

Shield the coil, the coronas effect is still as powerful on florescents,
vtvms detecting voltage... that voltage may well be inducing a magnetic
field as it is conducted by air/ether/ground... but it looks to me like the
voltage is the main force... rfi will tear up a neighborhood too...

Warmest regards,
John

"Frank" wrote in message
news:GVbje.7002$wr.3522@clgrps12...

"John Smith" wrote in message
...
Ham Op:

Yes, it is... mostly, people who are NOT gifted in explanations that the
"layman" can understand--gravitate to such extreme mathematics (and turn
them off, effectively silencing them).... let me give you my views...

I thought that my explanations were very non-mathematical, requiring only
minimal use of very simple calculations. My response was not complete as
I did not want to go overboard, but try to give very easy examples that
could be expanded on if any interest was shown. Perhaps you could be more
specific as to where I went wrong in my response. My mention of a couple
of textbooks was only to provide references for those interested in trying
to understand concepts in more detail. While it is true that some people
are capable of rigorous mathematical analysis, they cannot explain it in
non-mathematical terms. Those people, then, do not really understand
their subject. It is also true that such complex subjects cannot be fully
understood without in-depth math (Which is something I wish I had).
.
... it is somewhat obvious that when a wave sent forth from our antennas
encounters a metallic object that is close to resonate freq,

Not sure that resonance is important.
and a very good to EXCELLENT conductor, that a LARGE current flows in the
metallic structure encountered--

Current will flow in the surface.

what E and what H wave are then products are debatable (the energy
absorbed is re-radiated)--however--probably of a very different nature
than that of wave which encountered the metallic object in question--and
here is where this debate is ongoing...

If the conducting surface is perfect, no absorbtion takes place. The
reflected EM wave is planar, and identical to the incident plane wave --
with the exception of direction of propagation, and a phase reversal. A
(spatial) standing wave pattern is set up, and the analysis is identical
to that of a shorted transmission line.

at an extreme is a "tesla coil", ultimate voltage and virtually NO
current (very minimal current to generate the nice purple coronas)--yet
an excellent transmitting "antenna"--and that is ALL "E-wave." (well,
mostly...)

A Tesla coil is not an antenna, although some radiation will take place
from its conductors -- which will probably be damped sinusoidal pulses
similar to a spark transmitter. The radiation will not be all "E", but
will have the same E/H ratio of any radiated signal. i.e. E/H = 377
(ohms) in the far field.

73,

Frank


Warmest regards,
John

"Ham op" wrote in message
...
Isn't Kraus "Electromagnetics" a little heavy on the math for the
average Ham ??

Frank wrote:

Hank, and Richard, For a good explanation of this subject I always
liked the book: "Introduction to Electromagnetic Fields" by Paul and
Nasar. The first two chapters of mathematical review are excellent. I
see barnesandnoble.com has the 3rd edition, used, for as low as $66.
John D. Kraus' book; "Electromagnetics" is also a very good text.

73,

Frank

"John Smith" wrote in message
...
Shield the coil, the coronas effect is still as powerful on florescents,
vtvms detecting voltage... that voltage may well be inducing a magnetic
field as it is conducted by air/ether/ground... but it looks to me like
the voltage is the main force... rfi will tear up a neighborhood too...

Warmest regards,
John

Since I have never had experience with a Tesla coil, this is all relatively
new to me. After a little research I found the following information,
which may be of interest.

The Tesla coil design reference at
http://home.wtal.de/herbs_teslapage/design.html provides an Excel spread
sheet showing all the appropriate parameters. The spread sheet example
shows a single gap spark transmitter, of input power 375 W at a frequency of
322 kHz. Since the wavelength is relatively long, at 932 m, the near
field/far field transition is very close to the radiating structure, which
will include the conductive arc plasma.

Near field/far field transition is approximated as (2D^2)/lambda, where D is
the largest dimension of the radiating structure, and lambda is the
wavelength.

The observable effects you mention are therefore most likely due to far
field effects. The E/H ratio is still a constant at 377 ohms. From the
above formula you can see that you would have to be very close to the souce
for any inductive or capacative coupling to occur.

Having heard of Tesla coils I never realized they were only simple spark gap
transmitters.

73,

Frank

On Fri, 20 May 2005 02:26:46 GMT, "Frank"
wrote:


"John Smith" wrote in message
...
Ham Op:

Yes, it is... mostly, people who are NOT gifted in explanations that the
"layman" can understand--gravitate to such extreme mathematics (and turn
them off, effectively silencing them).... let me give you my views...

I thought that my explanations were very non-mathematical, requiring only
minimal use of very simple calculations. My response was not complete as I
did not want to go overboard, but try to give very easy examples that could
be expanded on if any interest was shown. Perhaps you could be more
specific as to where I went wrong in my response. My mention of a couple of
textbooks was only to provide references for those interested in trying to
understand concepts in more detail. While it is true that some people are
capable of rigorous mathematical analysis, they cannot explain it in
non-mathematical terms. Those people, then, do not really understand their
subject.

So they can discover some knowledge and use it to make
products or predictions, but if they cannot explain it in
non-mathematical terms to your satisfaction, then, by your lights,
they do not understand it?

As a counter example, consider the comments of Richard
Feynman. When he was awarded a Nobel prize for his work in (I believe)
quantum electrodynamics, he was honored at a luncheon provided by the
faculty wives at his university. During the proceedings, he was asked,
"Doctor Feynman, could you let us know, in simple terms, what your
work was about?" He answered, "Madam, if I could explain it in simple
terms, they wouldn't have given me the Nobel prize for it." Will you
contend he didn't understand his subject?

In addition, you fail to understand that discovering knowledge
and teaching it are entirely separate gifts. Some who understand
deeply are incapable of teaching. Others, with less than complete
understanding, can teach effectively, while being incapable of coming
up with the knowledge in the first place.

One of our most poisonous (and arrogant) sayings is the one
which states, "Those who can, do; those who can't, teach." It's not
all that common to find people who can do both well.


It is also true that such complex subjects cannot be fully
understood without in-depth math (Which is something I wish I had).

Wherein you contradict yourself. You can't contend at the
samer time that a knowledge of mathematics on the part of the learner
is a necessity at the same time that you indict the one who can
explain only in mathematical terms for lack of understanding.

Heads or tails?

.
... it is somewhat obvious that when a wave sent forth from our antennas
encounters a metallic object that is close to resonate freq,

Not sure that resonance is important.
and a very good to EXCELLENT conductor, that a LARGE current flows in the
metallic structure encountered--

Current will flow in the surface.

what E and what H wave are then products are debatable (the energy
absorbed is re-radiated)--however--probably of a very different nature
than that of wave which encountered the metallic object in question--and
here is where this debate is ongoing...

If the conducting surface is perfect, no absorbtion takes place. The
reflected EM wave is planar, and identical to the incident plane wave --
with the exception of direction of propagation, and a phase reversal. A
(spatial) standing wave pattern is set up, and the analysis is identical to
that of a shorted transmission line.

at an extreme is a "tesla coil", ultimate voltage and virtually NO current
(very minimal current to generate the nice purple coronas)--yet an
excellent transmitting "antenna"--and that is ALL "E-wave." (well,
mostly...)

A Tesla coil is not an antenna, although some radiation will take place from
its conductors -- which will probably be damped sinusoidal pulses similar to
a spark transmitter. The radiation will not be all "E", but will have the
same E/H ratio of any radiated signal. i.e. E/H = 377 (ohms) in the far
field.

73,

Frank


Warmest regards,
John

"Ham op" wrote in message
...
Isn't Kraus "Electromagnetics" a little heavy on the math for the average
Ham ??

Frank wrote:

Hank, and Richard, For a good explanation of this subject I always liked
the book: "Introduction to Electromagnetic Fields" by Paul and Nasar.
The first two chapters of mathematical review are excellent. I see
barnesandnoble.com has the 3rd edition, used, for as low as $66. John
D. Kraus' book; "Electromagnetics" is also a very good text.

73,

Frank