Richard Clark wrote in
:

On Tue, 01 Dec 2009 03:42:13 -0600, Lostgallifreyan
wrote:

why is it
often ok for a Faraday cage to have holes in it? Braided screens,
meshes, perforated metal sheets, etc, I've seen many shields that are
not a complete 'seal'... UHF TV cables especially seem to be very
loosely shielded but they work.

This can be explained at super high frequency and at DC as easily.
However, before that it should be pointed out that the coverage (the
ratio of what is conductor to what is not - the air space) defines how
"good" the faraday shield will be. Not surprisingly, coverage is
wavelength dependant. To cut to the chase, a wide mesh will allow
increasingly higher frequencies (shorter waves) through.

Now, as to the how. With a separation in the mesh, and for very large
wavelength (in proportion to the opening size), you will have a very,
very small potential difference across any of the mesh openings. Very
little potential voltage across the mesh opening means very little
current flow around the mesh opening that is specifically due to that
potential difference.

This is not to say there isn't a very, very large current flow by
virtue of some very, very long wave. No, there's no denying that, but
to get through the mesh you have to satisfy local conditions that
demand what amounts to leakage (and this is exactly the term that
correlates to coverage when discussing coax weave). If that huge
current cannot induce a significant voltage across the mesh opening,
then the mesh opening loop current cannot induce a field through to
the other side. Now, if you examine the context of "huge current" in
a resistive conductor, then obviously a potential difference can
occur. Point is that reality (and science) allow for poor grade
shields, but as a one knock-off proof you can summon up any failure,
ignore simple contra-examples and create a new theory.

However, returning to what is well known. If you increase the
frequency applied to the mesh, then at some point wavelength will
allow a situation where the general current flowing through the whole
structure will naturally exhibit a potential difference across some
small scale. By this point, abstraction may be wearying.

Let's say you have a 10 meter-on-a-side cage with 1 meter mesh
openings. If your applied field were exciting the cage at 75MHz (4M),
then any spot on the cage could be at a very high potential difference
from any spot adjacent and 1 meter away (a simple quarterwave
relationship). This works for a solid conductor, it works for a mesh
conductor.

The 1 meter mesh openings can thus exhibit a substantial potential
difference across the opening, and a local current loop associated
with that potential difference. The mesh opening becomes a
quarterwave radiator (aka slot antenna) and can couple energy from the
external field into the interior of the cage (now possibly a resonant
chamber, aka RF cavity). In practice and literature, the mesh opening
loop exhibits a radiation resistance of 10s of Ohms. That compared to
its mesh loop Ohmic path loss, makes it a very efficient coupler of
energy.

Take this very poor example of mesh, and lower the frequency to 750
KHz. The mesh opening - if we originally likened it to an antenna, we
should be able to continue to do that - is now 1/400th Wave. A
1/400th wave radiator has extremely small radiation resistance. The
exact value would be 751 nanoOhms. As we are examining a poor mesh,
it becomes clear that it must have some resistance over that 1 meter
distance (this is a real example, after all).

Being generous and constructing that cage out of rebar will give us a
path resistance of, luckily, 1 milliOhm. This figure and that of the
radiation resistance yield the radiation efficiency (that is, how well
the exterior RF will couple into the interior) which reduces to
0.075%. The cage works pretty well, but not perfectly (it was, after
all, a poor example).

Now, repeat this with a poorer conductor, or a tighter mesh and
imagine the shielding effect. The mesh has an opening radius
squared-squared relationship driving down the radiation resistance
compared to the linear relationship of conductance.

*************

Now, expanding the topic to allow for the contribution of ALL openings
in the mesh, we must again return to the physical dimension compared
to the wavelength dimension. If the cage is truly large, larger than
the field exciting it, then you have miniscule radiators along it,
each very inefficient. However, each of those radiators is out of
phase with a distant neighbor (not so with its close mesh neighbors).
Those two wavelength distant mesh radiators will combine somewhere in
the interior space and build a field. This is very commonly found in
inter-cable cross coupling through leakage that is exhibited in very
long cable trays with tightly bound lines. This doesn't improve the
efficiency, but sensitive circuits running parallel to power drives
can prove to be a poor combination. What to do when conditions
condemn the small signal coax to live in proximity to the large signal
supply?

This introduces the foil shield. The foil shield is a very poor
conductor over any significant length, but over the span between mesh
openings (e.g. coax shield weave), the resistance is sufficiently low
to close the conductance gap.

73's
Richard Clark, KB7QHC


Thankyou. That IS a clear picture. I'll have to learn more to understand it
well but what I can grasp fits well with things I have already observed.

Regarding the other postings today, I can see that if you're receiving a long
wave signal a small system will do if the sensivity is good and the noise is
low, but transmission is another matter entirely. But whatever the theories
propounded might be, I guess the observations are what matters. I haven't the
space or equipment to test it, but if anyone manages to transmit a lot of
longwave RF from a small directional system such as Art Unwin appears to be
describing, then the theory will take care of itself, eventually, but I also
get the strong impression that few people, if any, have done it. As far as I
know, all low frequency RF transmitting systems are large, powerful things,
and not very directional.

(I wrote that yesterday but kept clear of the Send button, but it's on topic
enough to go for it now.)

On Dec 3, 2:28*am, Lostgallifreyan wrote:
Richard Clark wrote :



On Tue, 01 Dec 2009 03:42:13 -0600, Lostgallifreyan
wrote:

why is it
often ok for a Faraday cage to have holes in it? Braided screens,
meshes, perforated metal sheets, etc, I've seen many shields that are
not a complete 'seal'... UHF TV cables especially seem to be very
loosely shielded but they work.

This can be explained at super high frequency and at DC as easily.
However, before that it should be pointed out that the coverage (the
ratio of what is conductor to what is not - the air space) defines how
"good" the faraday shield will be. *Not surprisingly, coverage is
wavelength dependant. *To cut to the chase, a wide mesh will allow
increasingly higher frequencies (shorter waves) through.

Now, as to the how. *With a separation in the mesh, and for very large
wavelength (in proportion to the opening size), you will have a very,
very small potential difference across any of the mesh openings. *Very
little potential voltage across the mesh opening means very little
current flow around the mesh opening that is specifically due to that
potential difference.

This is not to say there isn't a very, very large current flow by
virtue of some very, very long wave. *No, there's no denying that, but
to get through the mesh you have to satisfy local conditions that
demand what amounts to leakage (and this is exactly the term that
correlates to coverage when discussing coax weave). *If that huge
current cannot induce a significant voltage across the mesh opening,
then the mesh opening loop current cannot induce a field through to
the other side. *Now, if you examine the context of "huge current" in
a resistive conductor, then obviously a potential difference can
occur. *Point is that reality (and science) allow for poor grade
shields, but as a one knock-off proof you can summon up any failure,
ignore simple contra-examples and create a new theory.

However, returning to what is well known. *If you increase the
frequency applied to the mesh, then at some point wavelength will
allow a situation where the general current flowing through the whole
structure will naturally exhibit a potential difference across some
small scale. *By this point, abstraction may be wearying.

Let's say you have a 10 meter-on-a-side cage with 1 meter mesh
openings. *If your applied field were exciting the cage at 75MHz (4M),
then any spot on the cage could be at a very high potential difference
from any spot adjacent and 1 meter away (a simple quarterwave
relationship). *This works for a solid conductor, it works for a mesh
conductor.

The 1 meter mesh openings can thus exhibit a substantial potential
difference across the opening, and a local current loop associated
with that potential difference. *The mesh opening becomes a
quarterwave radiator (aka slot antenna) and can couple energy from the
external field into the interior of the cage (now possibly a resonant
chamber, aka RF cavity). *In practice and literature, the mesh opening
loop exhibits a radiation resistance of 10s of Ohms. *That compared to
its mesh loop Ohmic path loss, makes it a very efficient coupler of
energy.

Take this very poor example of mesh, and lower the frequency to 750
KHz. *The mesh opening - if we originally likened it to an antenna, we
should be able to continue to do that - is now 1/400th Wave. *A
1/400th wave radiator has extremely small radiation resistance. *The
exact value would be 751 nanoOhms. *As we are examining a poor mesh,
it becomes clear that it must have some resistance over that 1 meter
distance (this is a real example, after all). *

Being generous and constructing that cage out of rebar will give us a
path resistance of, luckily, 1 milliOhm. *This figure and that of the
radiation resistance yield the radiation efficiency (that is, how well
the exterior RF will couple into the interior) which reduces to
0.075%. *The cage works pretty well, but not perfectly (it was, after
all, a poor example).

Now, repeat this with a poorer conductor, or a tighter mesh and
imagine the shielding effect. *The mesh has an opening radius
squared-squared relationship driving down the radiation resistance
compared to the linear relationship of conductance.

*************

Now, expanding the topic to allow for the contribution of ALL openings
in the mesh, we must again return to the physical dimension compared
to the wavelength dimension. *If the cage is truly large, larger than
the field exciting it, then you have miniscule radiators along it,
each very inefficient. *However, each of those radiators is out of
phase with a distant neighbor (not so with its close mesh neighbors).
Those two wavelength distant mesh radiators will combine somewhere in
the interior space and build a field. *This is very commonly found in
inter-cable cross coupling through leakage that is exhibited in very
long cable trays with tightly bound lines. *This doesn't improve the
efficiency, but sensitive circuits running parallel to power drives
can prove to be a poor combination. *What to do when conditions
condemn the small signal coax to live in proximity to the large signal
supply?

This introduces the foil shield. *The foil shield is a very poor
conductor over any significant length, but over the span between mesh
openings (e.g. coax shield weave), the resistance is sufficiently low
to close the conductance gap.

73's
Richard Clark, KB7QHC

Thankyou. That IS a clear picture. I'll have to learn more to understand it
well but what I can grasp fits well with things I have already observed.

Regarding the other postings today, I can see that if you're receiving a long
wave signal a small system will do if the sensivity is good and the noise is
low, but transmission is another matter entirely. But whatever the theories
propounded might be, I guess the observations are what matters. I haven't the
space or equipment to test it, but if anyone manages to transmit a lot of
longwave RF from a small directional system such as Art Unwin appears to be
describing, then the theory will take care of itself, eventually, but I also
get the strong impression that few people, if any, have done it. As far as I
know, all low frequency RF transmitting systems are large, powerful things,
and not very directional.

(I wrote that yesterday but kept clear of the Send button, but it's on topic
enough to go for it now.)

You only have to visualise a large solenoid to see that it is quite
directional.
Modeling shows in the order of 10 dbi when end fed !
If you have a helix antenna in ribbon shape form where all lumped
loads are canceled
then even Eznec should be able to do the job. No need for cross wires
for a single frequency design. A mesh made into a tube and placed on
the ground will also get the job done, no hand waving required. Put
mesh around a plastic garbage can also does the job and Menards have
the mesh for less than $20 and muriatic acis for $4.
It is just that hams cannot accept change or even small non electrical
antennas.
After all, all is known about antennas as they have been studied to
death.

On Thu, 03 Dec 2009 02:28:26 -0600, Lostgallifreyan
wrote:

Regarding the other postings today, I can see that if you're receiving a long
wave signal a small system will do if the sensivity is good and the noise is
low, but transmission is another matter entirely.

Reciprocity dominates, but transmit and receive circuits are not
always reciprocal (that is, symmetric or identical). If you match at
the antenna, you don't lose signal in the loss of the transmission
line where SWR would dominate. That topic is best left to other
discussion.

But whatever the theories
propounded might be, I guess the observations are what matters. I haven't the
space or equipment to test it, but if anyone manages to transmit a lot of
longwave RF from a small directional system such as Art Unwin appears to be
describing, then the theory will take care of itself, eventually, but I also
get the strong impression that few people, if any, have done it. As far as I
know, all low frequency RF transmitting systems are large, powerful things,
and not very directional.

In logic there is the argument called Reductio Ad Absurdum. With the
claim of a resonant small antenna being efficient there exists an
obvious example that completely disrupts this. Since the inception of
man-made RF radiation, ALL such attempts have been preceded with a
resonant coil/capacitor combination. Think of the plate load of the
conventional RF transmitter in both amateur and professional
applications for the many decades that followed Hertz' work.

This small, resonant plate load, is quite specifically designed for RF
with low in resistive loss - and yet it is miserable as a propagator
of that same RF. The physical size compared to the wavelength size
dominates that efficiency with a fourth power law. Hertz' original
design was in the VHF where his "plate tank" (so to speak) was
physically large in relation to the wavelength he successfully
transmitted to a nearby physically large receiving tank.

73's
Richard Clark, KB7QHC

On Dec 3, 12:29*pm, Richard Clark wrote:
On Thu, 03 Dec 2009 02:28:26 -0600, Lostgallifreyan

wrote:
Regarding the other postings today, I can see that if you're receiving a long
wave signal a small system will do if the sensivity is good and the noise is
low, but transmission is another matter entirely.

Reciprocity dominates, but transmit and receive circuits are not
always reciprocal (that is, symmetric or identical). *If you match at
the antenna, you don't lose signal in the loss of the transmission
line where SWR would dominate. *That topic is best left to other
discussion.

But whatever the theories
propounded might be, I guess the observations are what matters. I haven't the
space or equipment to test it, but if anyone manages to transmit a lot of
longwave RF from a small directional system such as Art Unwin appears to be
describing, then the theory will take care of itself, eventually, but I also
get the strong impression that few people, if any, have done it. As far as I
know, all low frequency RF transmitting systems are large, powerful things,
and not very directional.

In logic there is the argument called Reductio Ad Absurdum. *With the
claim of a resonant small antenna being efficient there exists an
obvious example that completely disrupts this. *Since the inception of
man-made RF radiation, ALL such attempts have been preceded with a
resonant coil/capacitor combination. *Think of the plate load of the
conventional RF transmitter in both amateur and professional
applications for the many decades that followed Hertz' work.

This small, resonant plate load, is quite specifically designed for RF
with low in resistive loss - and yet it is miserable as a propagator
of that same RF. *The physical size compared to the wavelength size
dominates that efficiency with a fourth power law. *Hertz' original
design was in the VHF where his "plate tank" (so to speak) was
physically large in relation to the wavelength he successfully
transmitted to a nearby physically large receiving tank.

73's
Richard Clark, KB7QHC

A perfect example of an old man or woman not willing to accept change.
For the cost of a few dollars they would not have made such fools of
themselves over the years.
I have stated many times that adding a time varying current to a
Gaussian field of statics
represents Maxwells laws for radiation. The group many times over say
this is foolish and stupid. I know it is not stated or confirmed in
the books. When one accept that statement of mine the next deductions
become obvious.
A radiator can be any size, shape or elevation as long as it is in a
state of equilibrium and is in compliance with Maxwells equation for
radiation.
I have opreviously shown how static particles are part and parcel how
a Faraday shield works. I now have shown again how Maxwell and Gauss
also state that particles are part of radiation. In addition, the
particle is also part of a CRT mechanism as is the salvage sorting
system when sorting aluminum cans. I have also shown how the particle
achieves a straight line trajectory with spin unaffected by gravity
which is also essential to radio propagation.
Yet hams still hang on to the yagi and all its atributes as being the
cats whiskers.
Thus size has become everything and the volume it occupies instead of
distributed loads only as long as it is in equilibrium. The particle
responsible for radiation and light is very small and is the perfect
example of point radiation at its best.
All it takes is a few dollars and a few hours work to make such an
antenna, which allows you to stop making idiots of your selves, or a
modicum of physics. Instead, you are all so sure that you find no need
to get up from a couch.
As I have stated many times, all the group has done is the waving of
hands with no physics attached or any explanation why it is in total
conformance with antenna computer programs of the day in addition to
the points I have made. With groups such as this it is no small wonder
that radiation has not been fully understood for more than a century.

On Thu, 03 Dec 2009 10:29:53 -0800, Richard Clark
wrote:

This small, resonant plate load, is quite specifically designed for RF
with low in resistive loss - and yet it is miserable as a propagator
of that same RF. The physical size compared to the wavelength size
dominates that efficiency with a fourth power law.

To extend this to Art's misinterpretation of Faraday Shields:

In the old days, breadboard design was exactly that - your rig was
built on (hammered to) a breadboard. It was open wiring with open
components. It radiated well with an antenna, and poorly without one.

However, as poorly as it radiated without an antenna, if you had a
separate receiver, you would hear yourself. This was sometimes useful
and gave us what is called "side tone."

The monitor was born.

Of course, with antennas connected, the receiver was bound to get more
than enough of that anyway and if the two were closely spaced,
feedback could drive all circuits into saturation. Not a good thing.
The Faraday shield for the transmitter was born.

It, as many can witness from simple observation, was composed of a
fine grid mesh of wire either tied to ground, or to a heavily AC/RF
filtered DC potential. As with all Faraday shields that came before
it (indeed since Faraday invented it), it completely encapsulated the
RF power source. The screen or mesh was simply a contrivance to allow
cool air to move in and hot air to move out. Modern implementations
use finned constructions and heat wicks - but this is topic drift.

With this added to the breadboard, other circuits also came to be
shielded, and generally so with the appearance of sheet metal chassis
with suitably wavelength small openings for access and heat transfer.
As the breadboard went into this RF impenetrable shell for both
receivers and transmitters (and with even more care for transceivers),
there arose a problem: What about the wires that go in and out?

Yes indeed. If those wires were not, in themselves, decoupled; then
they became radiators. The lesson to be learned was that those wires
had to be held at the same potential as the Faraday shield. This
could be accomplished by a simple connection, but with more than one
wire this leads to dead shorts between wires. Not a good thing.

The solution was to use AC/RF shorts (capacitors) to the shield from
the wire and the wire could only penetrate the shield through a very
small (in proportion to wavelength) opening. This was not always a
good thing.

A capacitor could be good, but it exhibits a roll-off of only 6dB per
octave, or 10dB per decade isolation. If your line going in and out
was a DC control line, and your principle frequency was 1MHz (talking
about the old days now); then you had 6 decades of separation between
1Hz and 1MHz - pretty good. If in the intervening years you pushed
the technology envelope and added voice modulation and that came
through the same wire; then your system shrunk to 3 decades of
separation between 10,000Hz and 1MHz. This might work, sometimes it
didn't.

As the years spun on, more wires penetrated that RF barrier, and they
needed to not only be isolated from the RF, but each other; and often
they contained very small signals that needed suitable signal to noise
ratio (noise being that soup of RF that was stewing inside the
shield).

Inline bypass filters were born.

The lines that penetrate a Faraday shield now appear to be more
multi-stage low pass filters with repeating sections of shunt
capacitors and series inductors. Their common (ground to the old
brass pounder) was the shield which was RF free (as it was decoupled
to a sanctioned earth ground). And lest we forget the principle
penetration of that old time Faraday shield:

The coaxial transmission line was born.

By all appearances, this line satisfies the convention of a small
opening through the Faraday shield. It's diameter is easily very
small in relation to the wavelength of the RF power it reaches into
the shield to tap. In a sense, it extends that hole in the shield to
some very remote area that is far from the operating position, and
then allows a wire(s) to emerge without regard for further shielding:

The antenna is born.

Funny thing, however, is that presumption of the shield of the coax
being inert, un-perturbing, quiescent, invisible, benign - for that
presumption is an illusion, a grand delusion. The line is very long
with respect to wavelength, it is in the field of excitation that has
been drawn out of the soup within the cage, and it is as much an
antenna as the wire that emerged from its end. Many familiar problems
rise from the ashes of this illusion. The exterior of the coaxial
cable appears to the field to be a very long, grounded radiator.
However, at any appreciable length (wavelength raises its familiar
visage with an ironic grin), this exterior surface ceases to be the
familiar DC grounding strap material, and becomes a full-fledge
radiator according to its physical length vs. wavelength relationship.
Not a very good thing, untill:

The transmission line choke is born.

To decouple the OUTSIDE of the coaxial line, the convention that has
been observed (to widespread validation) is to either wind some
sections of the line into Inductive chokes, or to add ferrites which
serve the same purpose. These chokes, to be fully useful to their
purpose, should be found at not only one point along the line, but at
several so as to suppress (wavelength based) couplings along the line,
by the line and by the field.

When the combination of all these methods are employed, then the
Faraday shield does what it has done for these several hundred years
while allowing the migration of RF power to a remote drive point, and
without allowing that RF power to re-intrude into the shield, nor
along the coaxial cable. Thus, the only evidence of RF from inside
the Faraday shield is that which arrives over-the-air from the remote
antenna.

Any other claim is a profanation of Faraday.

73's
Richard Clark, KB7QHC

On Thu, 03 Dec 2009 13:37:05 -0800, Richard Clark
wrote:

Yes indeed. If those wires were not, in themselves, decoupled; then
they became radiators.

Further discussion about these wires allowing RF to slither through
what would ordinarily be impenetrable holes.

Those holes, whose circulating currents prohibit any coupling of
fields through them, as long as they are very small in relation to the
wavelength, can turn into free-flowing fountains of power with some
rather simple additions.

As mentioned, merely pass an insulated wire through the hole. If that
wire reaches into the interior where an RF field presents a very high
potential difference to the Faraday shield, then you have a capacitive
coupling to the exterior of the shield, through the hole, along that
wire. On the other hand, if you loop that interior wire back onto the
interior surface of the shield, AND that loop resides within the RF
field where it presents a very high magnetic component; then you have
an inductive coupling to the exterior of the shield, through the hole,
along that wire. Simply terminate the outside extension of that wire
to a suitable load, observing the conventions of matching, and remove
as much power as is practicable.

This is nothing more complex than the usual design conventions already
discussed under the coaxial transmission line considerations in the
post this derives from.

The point of this aside is to remark how easily (or difficulty) the
Faraday shield can be corrupted through indifference to first
principles.

73's
Richard Clark, KB7QHC

On Dec 3, 3:37*pm, Richard Clark wrote:
On Thu, 03 Dec 2009 10:29:53 -0800, Richard Clark
wrote:

This small, resonant plate load, is quite specifically designed for RF
with low in resistive loss - and yet it is miserable as a propagator
of that same RF. *The physical size compared to the wavelength size
dominates that efficiency with a fourth power law.

To extend this to Art's misinterpretation of Faraday Shields:

In the old days, breadboard design was exactly that - your rig was
built on (hammered to) a breadboard. *It was open wiring with open
components. *It radiated well with an antenna, and poorly without one.

However, as poorly as it radiated without an antenna, if you had a
separate receiver, you would hear yourself. *This was sometimes useful
and gave us what is called "side tone." *

The monitor was born.

Of course, with antennas connected, the receiver was bound to get more
than enough of that anyway and if the two were closely spaced,
feedback could drive all circuits into saturation. *Not a good thing.
The Faraday shield for the transmitter was born.

It, as many can witness from simple observation, was composed of a
fine grid mesh of wire either tied to ground, or to a heavily AC/RF
filtered DC potential. *As with all Faraday shields that came before
it (indeed since Faraday invented it), it completely encapsulated the
RF power source. *The screen or mesh was simply a contrivance to allow
cool air to move in and hot air to move out. *Modern implementations
use finned constructions and heat wicks - but this is topic drift.

With this added to the breadboard, other circuits also came to be
shielded, and generally so with the appearance of sheet metal chassis
with suitably wavelength small openings for access and heat transfer.
As the breadboard went into this RF impenetrable shell for both
receivers and transmitters (and with even more care for transceivers),
there arose a problem: *What about the wires that go in and out?

Yes indeed. *If those wires were not, in themselves, decoupled; then
they became radiators. *The lesson to be learned was that those wires
had to be held at the same potential as the Faraday shield. *This
could be accomplished by a simple connection, but with more than one
wire this leads to dead shorts between wires. *Not a good thing.

The solution was to use AC/RF shorts (capacitors) to the shield from
the wire and the wire could only penetrate the shield through a very
small (in proportion to wavelength) opening. *This was not always a
good thing.

A capacitor could be good, but it exhibits a roll-off of only 6dB per
octave, or 10dB per decade isolation. *If your line going in and out
was a DC control line, and your principle frequency was 1MHz (talking
about the old days now); then you had 6 decades of separation between
1Hz and 1MHz - pretty good. *If in the intervening years you pushed
the technology envelope and added voice modulation and that came
through the same wire; then your system shrunk to 3 decades of
separation between 10,000Hz and 1MHz. *This might work, sometimes it
didn't.

As the years spun on, more wires penetrated that RF barrier, and they
needed to not only be isolated from the RF, but each other; and often
they contained very small signals that needed suitable signal to noise
ratio (noise being that soup of RF that was stewing inside the
shield). *

Inline bypass filters were born.

The lines that penetrate a Faraday shield now appear to be more
multi-stage low pass filters with repeating sections of shunt
capacitors and series inductors. *Their common (ground to the old
brass pounder) was the shield which was RF free (as it was decoupled
to a sanctioned earth ground). *And lest we forget the principle
penetration of that old time Faraday shield:

The coaxial transmission line was born.

By all appearances, this line satisfies the convention of a small
opening through the Faraday shield. *It's diameter is easily very
small in relation to the wavelength of the RF power it reaches into
the shield to tap. *In a sense, it extends that hole in the shield to
some very remote area that is far from the operating position, and
then allows a wire(s) to emerge without regard for further shielding:

The antenna is born.

Funny thing, however, is that presumption of the shield of the coax
being inert, un-perturbing, quiescent, invisible, benign - for that
presumption is an illusion, a grand delusion. *The line is very long
with respect to wavelength, it is in the field of excitation that has
been drawn out of the soup within the cage, and it is as much an
antenna as the wire that emerged from its end. *Many familiar problems
rise from the ashes of this illusion. *The exterior of the coaxial
cable appears to the field to be a very long, grounded radiator.
However, at any appreciable length (wavelength raises its familiar
visage with an ironic grin), this exterior surface ceases to be the
familiar DC grounding strap material, and becomes a full-fledge
radiator according to its physical length vs. wavelength relationship.
Not a very good thing, untill:

The transmission line choke is born.

To decouple the OUTSIDE of the coaxial line, the convention that has
been observed (to widespread validation) is to either wind some
sections of the line into Inductive chokes, or to add ferrites which
serve the same purpose. *These chokes, to be fully useful to their
purpose, should be found at not only one point along the line, but at
several so as to suppress (wavelength based) couplings along the line,
by the line and by the field.

When the combination of all these methods are employed, then the
Faraday shield does what it has done for these several hundred years
while allowing the migration of RF power to a remote drive point, and
without allowing that RF power to re-intrude into the shield, nor
along the coaxial cable. *Thus, the only evidence of RF from inside
the Faraday shield is that which arrives over-the-air from the remote
antenna.

Any other claim is a profanation of Faraday.

73's
Richard Clark, KB7QHC

So after a degree in literature you have taken to reading up on
science.
But you have only regurgutated what you have read in a physics book.
When I introduced this group to first principles every body on this
group were apaulled.
When I stated, and it was confirmed by Dr Davis, all started waving
the hands and insulted Davis and I." What" you said "you can mix up
statics with electromechanics"? "What foolishness is being stated
here." In your posting you never mentioned any thing of that!
You and nobody in the group has presented anything that refutes what I
have stated.
All this group have agreed on is that I am promoting a new fangled
science where all is already known. Now Avitar has never stated any
sort of physics that shows that he has studied in college other than
waving his hands. Ofcourse we have the ham who got kicked out of high
school so he couldn't graduate. Not his fault I might add, just some
mis understandings why he would not go to school, and it goes on. And
then we have Richard who says, why do we need new design antennas, we
have the yagi, what more can you want?
So the group is not going to rely on physics to disprove my comments
because they have found that deformation, insults and loud voices is
all they have to crush my claims, and it is just not working. Have
they made one? No. They know the true facts on radiation so they
continue to sit on the couch and wave their hands and yell

On Dec 3, 4:24*pm, Art Unwin wrote:

You and nobody in the group has presented anything that refutes what I
have stated.

I have, and on more than one occasion. But it goes through
your head faster than a blue light special announcement to the
average K-mart shopper.

They know the true facts on radiation so they
continue to sit on the couch and wave their hands and yell

I don't sit on a couch. I sit in an office style chair. And it
probably
should be replaced as it tends to molest my differential after a
while.
Needs more particuls between the frame and the top particul retaining
cover. Due to the weak force of my differential constantly being
supported by these particuls, they have achieved equilibrium and
no longer want to do any useful work.

On Dec 3, 5:35*pm, wrote:
On Dec 3, 4:24*pm, Art Unwin wrote:

You and nobody in the group has presented anything that refutes what I
have stated.

I have, and on more than one occasion. But it goes through
your head faster than a *blue light special announcement to the
average K-mart shopper.

They know the true facts on radiation so they
continue to sit on the couch and wave their hands and yell

I don't sit on a couch. I sit in an office style chair. And it
probably
should be replaced as it tends to molest my differential after a
while.
Needs more particuls between the frame and the top particul retaining
cover. Due to the weak force of my differential constantly being
supported by these particuls, they have achieved equilibrium and
no longer want to do any useful work.

No you have not!
Every thing comes back to the initial finding that
by adding a time varying current to the arbitrary border of Gauss
which surrounds
a field of static particles provides the same conditions implied by
Maxwell's equations.
The group denies this fact possibly because the word equilibrium was
not of their understanding. Without understanding the connection
between Maxwell and Gauss
with respect to the addition of time makes to a static field ala a
dynamic field, it is impossible to procede with respect to radiation.
If one starts from the middle of the story where coupling of waves is
considered a basic physics understanding the debate leads no where.
Now I am not asking people to follow solely the path of mathematics
but of the concepts involved where the presence of particles is
present., To start from a small portion of the current flow and
thinking in terms of DC or the suggestion that time varying fields
cannot surround a static field is just ludicrous. The subject is
Classical Physics and one should keep on subject if one is to fully
understand radiation. Denial of select parts of classical physics
without supplying reason ans substituting insults instead is not going
to solve anything. And as you did not graduate from high school it is
perfectly understandable that you will find difficulties in parts of
the debate and yet you would like to contribute to the debate. But
insults will not get the job done.
Of course one can go back to the basics of mathematics way back in
Arabic times where
the mere presence of an equal sign denotes equilibrium or balance. The
equal sign is part of Maxwells equations so equilibrium is in effect.
This immediatly tells you that any radiator considered must be a
function of a full wavelength or a period with respect to a continuing
variable sign wave. Immediately one should note that a half wave has
no place in our calculations as the two areas under curve for a period
can never be the same because of overshoot phenomina, thus it is the
period that is repeatable and to be used. One can also deduce that a
radiator must be in equilibrium to be part of the same reasoning thus
resonance on its own is not part of the mathematics. There are plenty
of ways to see how current thinking on antennas is certainly not
inline with the equations of Maxwell, thus it is very important to
start from "first "principles and not just accept the books. And that
the importance of adding time to a static field enclosed by an
arbitrary boundary to ensure the correct metrics will be used at the
outset.
Art

Art Unwin wrote:

No you have not!

Temper, temper little boy.

Every thing comes back to the initial finding that
by adding a time varying current to the arbitrary border of Gauss
which surrounds
a field of static particles provides the same conditions implied by
Maxwell's equations.

Made up physics again. Unproven by any math or demonstrable effects.
Try a new line of argument, this one gets you nowhere.

The group denies this fact possibly because the word equilibrium was
not of their understanding. Without understanding the connection
between Maxwell and Gauss
with respect to the addition of time makes to a static field ala a
dynamic field, it is impossible to procede with respect to radiation.
If one starts from the middle of the story where coupling of waves is
considered a basic physics understanding the debate leads no where.

Denied by the group because it contradicts everything that is proven to
work, as well as all published and mathematically backed theories.

And provide some proof. Even just a little. Rhetoric doesn't count.

You accuse others of sitting on their asses and not building antennas
and measuring them, when you have never once done it yourself.

I have built many antennas and provided many independent performance
measurements right here. And so has almost evreyone you argue with. We
all make things and MEASURE them. You don't.

Now I am not asking people to follow solely the path of mathematics
but of the concepts involved where the presence of particles is
present., To start from a small portion of the current flow and
thinking in terms of DC or the suggestion that time varying fields
cannot surround a static field is just ludicrous. The subject is
Classical Physics and one should keep on subject if one is to fully
understand radiation. Denial of select parts of classical physics
without supplying reason ans substituting insults instead is not going
to solve anything. And as you did not graduate from high school it is
perfectly understandable that you will find difficulties in parts of
the debate and yet you would like to contribute to the debate. But
insults will not get the job done.
Of course one can go back to the basics of mathematics way back in
Arabic times where
the mere presence of an equal sign denotes equilibrium or balance. The
equal sign is part of Maxwells equations so equilibrium is in effect.
This immediatly tells you that any radiator considered must be a
function of a full wavelength or a period with respect to a continuing
variable sign wave. Immediately one should note that a half wave has
no place in our calculations as the two areas under curve for a period
can never be the same because of overshoot phenomina, thus it is the
period that is repeatable and to be used. One can also deduce that a
radiator must be in equilibrium to be part of the same reasoning thus
resonance on its own is not part of the mathematics. There are plenty
of ways to see how current thinking on antennas is certainly not
inline with the equations of Maxwell, thus it is very important to
start from "first "principles and not just accept the books. And that
the importance of adding time to a static field enclosed by an
arbitrary boundary to ensure the correct metrics will be used at the
outset.

Uh Art? There are no rational concepts in your presentation, please
provide some.

And there's no "math" at all in your mathematical presentations, just a
bunch of bafflegab. Please provide math.

Oh, I forgot, you can't. All you can do is babble. And accuse people
of foolishness in their disbelief.

I must say, you are entertaining when you don't take your medications.

And you still can't spell or put together a sentence. I would suggest a
spell checker at the very least.

tom
K0TAR