On Monday, October 21, 2013 10:32:09 AM UTC-5, John S wrote:
Your interpretation of "permission" is only your interpretation. Please
do not infer for the rest of us.

Of course, everyone is free to infer whatever they please from Kraus' writings:

"The small horizontal loop antenna ... may be regarded as the *magnetic* counterpart of the short vertical dipole."

To me, the inference is clear. We may regard the small loop antenna as the magnetic counterpart to the short (implied electrical) dipole.
--
73, Cecil, w5dxp.com

Always learning John, but like to throw in a little
humor now and again.

de VE6BP Irv

"John S" wrote in message
...
On 10/21/2013 9:45 AM, Irv Finkleman wrote:
Magnetic, Shmagnetic! It works! A rose by any other
name would smell as sweet! :-)

de VE6BP Irv

True, if you are opposed to learning.

On 10/22/2013 04:23 AM, Jeff wrote:

Small loop implies a magnetic loop, magnetic loop implies a small loop,
so pretty much 6 of one and half a dozen of the other; although magnetic
loop does give more information on the mode of operation, which is
probably why the name has stuck.

Jeff

This is exactly the faulty line of reasoning to which I previously
provided comment. W5DXP's recent comments are on the mark.

Perhaps a metaphor is appropriate: You just might expertly pilot an
airplane you built from a kit but you don't necessarily possess the
expertise in aerodynamics/fluid mechanics to design a viable aircraft.
And the lack of that knowledge can result in the formulation of invalid
"principles of operation". Now, if you act right now we'll double your
order and send you two revolutionary "Crossed Field Antennas" and
include the matching carrying cases. Just pay separate shipping and
processing. Enough said. Sincerely,

--
J. B. Wood e-mail:

On 10/21/2013 10:50 PM, Irv Finkleman wrote:
Always learning John, but like to throw in a little
humor now and again.

de VE6BP Irv

"John S" wrote in message
...
On 10/21/2013 9:45 AM, Irv Finkleman wrote:
Magnetic, Shmagnetic! It works! A rose by any other
name would smell as sweet! :-)

de VE6BP Irv

True, if you are opposed to learning.

Sorry, Irv. I failed to notice the smiley face. My fault.

No problem John, all's well!

de VE6BP Irv

"John S" wrote in message
...
On 10/21/2013 10:50 PM, Irv Finkleman wrote:
Always learning John, but like to throw in a little
humor now and again.

de VE6BP Irv

"John S" wrote in message
...
On 10/21/2013 9:45 AM, Irv Finkleman wrote:
Magnetic, Shmagnetic! It works! A rose by any other
name would smell as sweet! :-)

de VE6BP Irv

True, if you are opposed to learning.

Sorry, Irv. I failed to notice the smiley face. My fault.

On 10/23/2013 02:37 AM, Jeff wrote:

Krause (and W5DXP) state that the small loop may be considered as a
magnetic aerial.

Jeff,

Kraus never uses the term "magnetic aerial". Kraus shows the
equivalence of "a small loop" and a "short magnetic dipole". Yes, the
short magnetic dipole (a theoretical construct) acts as a
radiator/interceptor of E-M energy (or photons if you prefer). In that
regard it is certainly an antenna, albeit a fictitious one. But any
antenna, regardless of geometry deals with E-M energy. You can't
decouple the E and H fields (as the Maxwell equations under time-varying
conditions clearly show). The "designers" of the CFA tried to do that
but ignored the applicable physics and ended up with a complicated and
expensive electrically short antenna.

So I think using a term like "magnetic loop antenna" or "electric dipole
antenna" is misleading. At the very least these terms are redundant and
at worst they imply that there are other types of antennas such as
"electric loop antennas". The "magnetic" modifier might imply the loop
antenna has certain properties due to the H-field exclusive of the E-field.

Also, just because hams have adopted a terminology doesn't imply
widespread use in the electrical engineering community. Many hams, such
as myself, are EEs. So maybe it's folks in that category that get more
incensed by these things.

Perhaps a metaphor is appropriate: You just might expertly pilot an
airplane you built from a kit but you don't necessarily possess the
expertise in aerodynamics/fluid mechanics to design a viable aircraft.
And the lack of that knowledge can result in the formulation of invalid
"principles of operation". Now, if you act right now we'll double your
order and send you two revolutionary "Crossed Field Antennas" and
include the matching carrying cases. Just pay separate shipping and
processing. Enough said. Sincerely,


How is any of that relevant to what something is generically called and
has been for years.


It's relevant in that despite the performance of the device (antenna,
airplance, etc) the explanation of "why it works" the way it does can
rely on faulty science. When those flawed principles are used to design
a device, that device often doesn't measure up to expectations. And the
designers often claim that others "just don't understand these things".
The Wright brothers were successful when others failed because, while
Orville and Wilbur were not formally trained as mechanical engineers,
they understood flight aerodynamics (as best as could be understood at
the time), and painstakingly applied that science to their aircraft
designs. They definitely weren't tinkerers or dilettantes. Sincerely,
and 73s from N4GGO,

--
J. B. Wood e-mail:

On Wednesday, October 23, 2013 6:07:45 AM UTC-5, J.B. Wood wrote:
So I think using a term like "magnetic loop antenna" or "electric dipole
antenna" is misleading.

A short loop antenna responds more to the magnetic field than the electric field. A short dipole responds more to the electric field than the magnetic field. A full-sized dipole or loop responds equally to both fields - that's why they are the most efficient.

I'm also a EE and maybe my experience with receiving antennas will shed some light. I have, in the past, been involved with 75m mobile shootout measurements. At first, we tried to use a 75m hamstick but human bodies close to the antenna affected the receive signal strengths considerably because of the effect of human bodies on the electric field. We switched over to ferrite rod antennas which, because they respond primarily to the magnetic field, are more immune to the effects of human bodies. Although you are correct in stating that all radio waves in free space are ElectroMagnetic waves, some antennas are more sensitive to the magnetic portion of the EM wave and some are more sensitive to the electric portion of the EM wave. Since antennas are, in general, reciprocal for receiving/transmitting, I can understand why some antennas are associated with the magnetic field of an EM wave and some are associated with the electric field of an EM wave.
--
73, Cecil, w5dxp.com

On 10/23/2013 03:26 PM, W5DXP wrote:
On Wednesday, October 23, 2013 6:07:45 AM UTC-5, J.B. Wood wrote:
So I think using a term like "magnetic loop antenna" or "electric dipole
antenna" is misleading.

A short loop antenna responds more to the magnetic field than the electric field. A short dipole responds more to the electric field than the magnetic field. A full-sized dipole or loop responds equally to both fields - that's why they are the most efficient.

I'm also a EE and maybe my experience with receiving antennas will shed some light. I have, in the past, been involved with 75m mobile shootout measurements. At first, we tried to use a 75m hamstick but human bodies close to the antenna affected the receive signal strengths considerably because of the effect of human bodies on the electric field. We switched over to ferrite rod antennas which, because they respond primarily to the magnetic field, are more immune to the effects of human bodies. Although you are correct in stating that all radio waves in free space are ElectroMagnetic waves, some antennas are more sensitive to the magnetic portion of the EM wave and some are more sensitive to the electric portion of the EM wave. Since antennas are, in general, reciprocal for receiving/transmitting, I can understand why some antennas are associated with the magnetic field of an EM wave and some are associated with the electric field of an EM wave.
--
73, Cecil, w5dxp.com

Sorry, Cecil, that while I usually agree with you I would take exception
to the "responds more" comment, if taken in the sense that it applies
everywhere. If the loop is being used as an inductive pickup, IOW in
the near field of a radiator or mutually coupled to another coil in
close proximity, then I can see that view. But not in the far field. In
the far field it would be just as correct to say that the loop responds
to the electric field. A better way of putting this IMO would be that
the loop (as a receiving antenna) in the far field (several wavelengths
removed from the transmitter) captures a portion of the E-M energy
incident upon it (what isn't captured is scattered). The amount of
energy captured is a function of the antenna's "effective area", which
depends upon antenna geometry and its orientation relative to the
incident energy (E/H field direction). Sincerely,

--
J. B. Wood e-mail:

On 10/23/2013 03:26 PM, W5DXP wrote:

We switched over to ferrite rod antennas which,
because they respond primarily to the magnetic field

Although you are correct in stating
that all radio waves in free space are ElectroMagnetic waves, some
antennas are more sensitive to the magnetic portion of the EM wave
and some are more sensitive to the electric portion of the EM wave.

If we're talking about radiant E-M energy, I can just as easily replace
anything attributed to the H-field component with the appropriate
E-field equivalent (using the Maxwell equations) and claim that field as
being the one to which the antenna is "sensitive". So the above
statements don't make sense. Again I'm assuming far-field, not close-in
coupling. Also, as I previously pointed out, I think this line of
thinking may have started from close-in coupling action but has been
incorrectly extended to everywhere. I've met some folks who think that
loop and dipole antennas, used as radiators, "transmit" the H and E
fields, respectively, without further elaboration. Sincerely,

--
J. B. Wood e-mail:

On Thursday, October 24, 2013 5:54:05 AM UTC-5, J.B. Wood wrote:
So the above statements don't make sense.

I agree that the E/M ratio for far field signals in space is a constant. That doesn't prohibit a receiving antenna from creating its own unique near-field conditions and altering that ratio just as there is nothing prohibiting a load from altering the E/M ratio that exists in a transmission line. In fact, the E/M ratio must necessarily be altered at impedance discontinuities.

Example: Two different antennas are receiving the same signal and indicating the same signal level. As a human walks close to the two antennas, the received signal strength of one antenna changes radically while the received signal strength of the other is affected by only a small amount. If both antennas were *accepting* the same fixed far-field E/M ratio, a human body should have the same effect on both antennas but we can demonstrate that it doesn't.
--
73, Cecil, w5dxp.com