loop antennas
 

This site http://www.frontiernet.net/~jadale/Loop.htm states that: "A
properly designed Loop primarily responds to the magnetic component of the
radio wave. Note that noise resides primarily in the electrical
component..."

Whereas this site shows that that is not the case:
http://vk1od.net/antenna/shieldedloop.

So what is the advantage, if any, of a shielded loop antanna?

Consider three receivers:

1) Shielded loop antenna, receiver with differential input (center-tapped
transformer or instrumentation amp). The two ends of the inner conductor
of the antenna connected to the differential inputs and the shield
connected to ground.

2) Same as above but without the shield.

3) Unshielded loop antenna, receiver with single-ended input.
One end of the loop connected to the receiver input and the other to
ground.

Assuming equal gains and bandwidths, would there be any
difference in the sensitivity or noise level at the output of the three
receivers?

loop antennas
 

On 6/13/2012 5:11 PM, garyr wrote:
This site http://www.frontiernet.net/~jadale/Loop.htm states that: "A
properly designed Loop primarily responds to the magnetic component of the
radio wave. Note that noise resides primarily in the electrical
component..."

Whereas this site shows that that is not the case:
http://vk1od.net/antenna/shieldedloop.

So what is the advantage, if any, of a shielded loop antanna?

None. The only purpose is to ensure balance, which helps give
deeper nulls.

But that is not the only way to ensure balance. A shield is
not required for that function.
None of my AM-BC loops are shielded. I have tried shielded
loops though, just to see for myself if any difference.
There no difference, assuming all of the loops were balanced
and fed properly.
The mythology of loops is a lot like the various myths you
see pertaining to grounds, and grounding. :|
Some claim a shielded loop is "quieter" than an unshielded loop.
I know from testing, that is pure hogwash.
Both are quite capable of picking up noise. After all, noise is
RF just like any other signal, and follows all the same rules.
The true test of a small loop is how deep the nulls are.
If you can make daytime AM ground wave signals disappear by
turning the loop, you are in pretty good shape.
And *any* small loop is capable of that if all is well in the
world.

loop antennas
 

"NM5K" napisal w wiadomosci
...
On 6/13/2012 5:11 PM, garyr wrote:
This site http://www.frontiernet.net/~jadale/Loop.htm states that: "A
properly designed Loop primarily responds to the magnetic component of
the
radio wave. Note that noise resides primarily in the electrical
component..."

Whereas this site shows that that is not the case:
http://vk1od.net/antenna/shieldedloop.

"The operation of the shielded loop is explained popularly by first stating
that the desired loop current is due to the magnetic field, and then
maintaining that the metal shield cannot be penetrated by the electric field
but can be penetrated by the magnetic field. All these arguments are
incorrect in the light of fundamental electromagnetic principles."

So what is the advantage, if any, of a shielded loop antanna?

None. The only purpose is to ensure balance, which helps give
deeper nulls.

But that is not the only way to ensure balance. A shield is
not required for that function.
None of my AM-BC loops are shielded. I have tried shielded
loops though, just to see for myself if any difference.

Do you use them to the "direction finding"?

"The advantage of this feed arrangement is that the coaxial feed typically
enters the loop opposite to the gap, and if attention is paid to symmetry of
the loop and feed, the balance that is achieved. Best balance yields the
deepest null which is important in direction finding applications for
instance."
S*

..

loop antennas
 

On 06/13/2012 06:11 PM, garyr wrote:
This site http://www.frontiernet.net/~jadale/Loop.htm states that: "A
properly designed Loop primarily responds to the magnetic component of the
radio wave. Note that noise resides primarily in the electrical
component..."

Hello, and a loop (dipole) antenna doesn't "respond" to just the
magnetic (electric) component of a propagating electromagnetic wave. A
(receiving) loop or dipole antenna intercepts the incoming
electromagnetic (EM) wave. Last time I checked an EM wave had both
electric and magnetic components. Just because an orientation of an
axis of the antenna resulting in maximum signal strength is parallel to
the electric or magnetic component of an EM wave doesn't mean that it's
responding to just that component.

I wish hams and others would quit trying to redefine electromagnetic
theory. Hams have designed and constructed novel and practical antennas
over the years but their explanations about how they work are often just
plain wrong. Sincerely, and 73s from N4GGO,

--
J. B. Wood e-mail:

loop antennas
 

El 14-06-12 0:11, garyr escribió:
This site http://www.frontiernet.net/~jadale/Loop.htm states that: "A
properly designed Loop primarily responds to the magnetic component of the
radio wave. Note that noise resides primarily in the electrical
component..."

Whereas this site shows that that is not the case:
http://vk1od.net/antenna/shieldedloop.

So what is the advantage, if any, of a shielded loop antanna?

Consider three receivers:

1) Shielded loop antenna, receiver with differential input (center-tapped
transformer or instrumentation amp). The two ends of the inner conductor
of the antenna connected to the differential inputs and the shield
connected to ground.

2) Same as above but without the shield.

3) Unshielded loop antenna, receiver with single-ended input.
One end of the loop connected to the receiver input and the other to
ground.

Assuming equal gains and bandwidths, would there be any
difference in the sensitivity or noise level at the output of the three
receivers?


I agree with your second link (by VK1OD).

The time varying magnetic field generates an electric field and that
is received by the loop. When you screen it completely, it doesn't
work, you need the gap.

By placing the gap opposite to the feed point, you get a balanced loop
without the need of ferrite or other constructions. If you can get
balance via other means, you don't need the screen. Balancing the
loop reduces noise due to common mode issues. This isn't different
from using a balun between a coaxial cable and a symmetrical dipole.

Your option three may behave competently different, as the coaxial
cable, power supply cable, switch mode power supply, etc may
contribute to reception of signal and noise due to common mode to
differential mode conversion.

From my experience (reception) with electrically small well-balanced
indoor loops and indoor dipoles, I found some advantage of the loop
over the electric dipole at low frequencies (say below 3 MHz). I
contribute this mainly because of the nulling capability. Whether is
applies to your location depends on the field distribution of the
noise at your location.

At higher frequencies there is difference in S/N ratio, but not in
favor of one antenna. Sharp nulling wasn't possible. So to know what
option is best for you, you need to try it. Maybe install both options
and select the antenna that gives best results as this will depend on
frequency and the angle of arrival of the radiation you want to receive.

Other thing that may really help is to find your local source(s) of
noise, use lots of ferrites and try to find a sweet spot for best S/N
ratio.

--
Wim
PA3DJS
www.tetech.nl
Please remove abc first in case of PM

loop antennas
 

"Szczepan Bialek" wrote in message
...


Do you use them to the "direction finding"?

S*
Amateur radio DF on VHF (very popular) tends to use yagis.
Loops seem to be used more for MW and HF DF.


Regards, Ian.

loop antennas
 

"J.B. Wood" napisal w wiadomosci
...
On 06/13/2012 06:11 PM, garyr wrote:
This site http://www.frontiernet.net/~jadale/Loop.htm states that: "A
properly designed Loop primarily responds to the magnetic component of
the
radio wave. Note that noise resides primarily in the electrical
component..."

Hello, and a loop (dipole) antenna doesn't "respond" to just the magnetic
(electric) component of a propagating electromagnetic wave. A (receiving)
loop or dipole antenna intercepts the incoming electromagnetic (EM) wave.
Last time I checked an EM wave had both electric and magnetic components.
Just because an orientation of an axis of the antenna resulting in maximum
signal strength is parallel to the electric or magnetic component of an EM
wave doesn't mean that it's responding to just that component.

I wish hams and others would quit trying to redefine electromagnetic
theory. Hams have designed and constructed novel and practical antennas
over the years but their explanations about how they work are often just
plain wrong. Sincerely, and 73s from N4GGO,

The explanations are wrong because the radio waves are simply the electric
waves or the electron waves.
From this point of view the next is obvious;
"Since the directional response of small loop antennas includes a sharp null
in the direction normal to the plane of the loop, they are used in radio
direction finding at longer wavelengths. The loop is thus rotated to find
the direction of the null."

" Although a similar argument may seem to apply to signals received in that
plane, that voltages generated by an impinging radio wave would cancel along
the loop, this is not quite true due to the phase difference between the
arrival of the wave at the near side and far side of the loop."
From: http://en.wikipedia.org/wiki/Loop_antenna
S*

loop antennas
 

On 6/14/2012 3:33 AM, Szczepan Bialek wrote:


But that is not the only way to ensure balance. A shield is
not required for that function.
None of my AM-BC loops are shielded. I have tried shielded
loops though, just to see for myself if any difference.

Do you use them to the "direction finding"?

No. I use them for MW broadcast reception.
I generally don't use them much above the 160m band.
My largest loop covering from longwave to about 2 MHZ,
using switchable caps.

loop antennas
 

On 06/14/2012 12:48 PM, Szczepan Bialek wrote:
"J.B. napisal w wiadomosci
...
On 06/13/2012 06:11 PM, garyr wrote:
This site http://www.frontiernet.net/~jadale/Loop.htm states that: "A
properly designed Loop primarily responds to the magnetic component of
the
radio wave. Note that noise resides primarily in the electrical
component..."

Hello, and a loop (dipole) antenna doesn't "respond" to just the magnetic
(electric) component of a propagating electromagnetic wave. A (receiving)
loop or dipole antenna intercepts the incoming electromagnetic (EM) wave.
Last time I checked an EM wave had both electric and magnetic components.
Just because an orientation of an axis of the antenna resulting in maximum
signal strength is parallel to the electric or magnetic component of an EM
wave doesn't mean that it's responding to just that component.

I wish hams and others would quit trying to redefine electromagnetic
theory. Hams have designed and constructed novel and practical antennas
over the years but their explanations about how they work are often just
plain wrong. Sincerely, and 73s from N4GGO,

The explanations are wrong because the radio waves are simply the electric
waves or the electron waves.

Hello, and they are most certainly not "electric" waves. What part of
"electromagnetic" don't you understand? (It's just this kind of stuff
that prompted my previous post) I take it you're not an EE or have ever
taken any undergrad/grad courses in EM theory. In any event someone
else can continue this starting-to-drift off topic thread. Sincerely,

--
J. B. Wood e-mail:

loop antennas
 

On 6/14/2012 12:50 PM, J.B. Wood wrote:
On 06/14/2012 12:48 PM, Szczepan Bialek wrote:
"J.B. napisal w wiadomosci
...
On 06/13/2012 06:11 PM, garyr wrote:
This site http://www.frontiernet.net/~jadale/Loop.htm states that: "A
properly designed Loop primarily responds to the magnetic component of
the
radio wave. Note that noise resides primarily in the electrical
component..."

Hello, and a loop (dipole) antenna doesn't "respond" to just the
magnetic
(electric) component of a propagating electromagnetic wave. A
(receiving)
loop or dipole antenna intercepts the incoming electromagnetic (EM)
wave.
Last time I checked an EM wave had both electric and magnetic
components.
Just because an orientation of an axis of the antenna resulting in
maximum
signal strength is parallel to the electric or magnetic component of
an EM
wave doesn't mean that it's responding to just that component.

I wish hams and others would quit trying to redefine electromagnetic
theory. Hams have designed and constructed novel and practical antennas
over the years but their explanations about how they work are often just
plain wrong. Sincerely, and 73s from N4GGO,

The explanations are wrong because the radio waves are simply the
electric
waves or the electron waves.

Hello, and they are most certainly not "electric" waves. What part of
"electromagnetic" don't you understand? (It's just this kind of stuff
that prompted my previous post) I take it you're not an EE or have ever
taken any undergrad/grad courses in EM theory. In any event someone else
can continue this starting-to-drift off topic thread. Sincerely,


He is either an idiot, an ignorant guy that refuses to learn, or a troll.

It doesn't matter all that much actually.

tom
K0TAR

loop antennas
 

"J.B. Wood" napisal w wiadomosci
...
On 06/14/2012 12:48 PM, Szczepan Bialek wrote:
"J.B. napisal w wiadomosci
...
On 06/13/2012 06:11 PM, garyr wrote:
This site http://www.frontiernet.net/~jadale/Loop.htm states that: "A
properly designed Loop primarily responds to the magnetic component of
the
radio wave. Note that noise resides primarily in the electrical
component..."

Hello, and a loop (dipole) antenna doesn't "respond" to just the
magnetic
(electric) component of a propagating electromagnetic wave. A
(receiving)
loop or dipole antenna intercepts the incoming electromagnetic (EM)
wave.
Last time I checked an EM wave had both electric and magnetic
components.
Just because an orientation of an axis of the antenna resulting in
maximum
signal strength is parallel to the electric or magnetic component of an
EM
wave doesn't mean that it's responding to just that component.

I wish hams and others would quit trying to redefine electromagnetic
theory. Hams have designed and constructed novel and practical antennas
over the years but their explanations about how they work are often just
plain wrong. Sincerely, and 73s from N4GGO,

The explanations are wrong because the radio waves are simply the
electric
waves or the electron waves.

Hello, and they are most certainly not "electric" waves.

For the all Fathers of the radio they are the electric waves.

What part of "electromagnetic" don't you understand?

I understand the Maxwell's and the Heaviside's. What are you asking about?

(It's just this kind of stuff that prompted my previous post) I take it
you're not an EE or have ever taken any undergrad/grad courses in EM
theory.

Father's of the radio also.
Maxwell's model was discarded by Royal Society and the Heaviside's was done
after the fundamental experimments.
Radio waves and light are the oscillatory flow of electrons (L. Lorenz
1869).

In any event someone else can continue this starting-to-drift off topic
thread. Sincerely,

You wrote: "Hams have designed and constructed novel and practical antennas
over the years but their explanations about how they work are often just
plain wrong."

Could you give as the correct explanation?
S*

--
J. B. Wood e-mail:

loop antennas
 

"Szczepan Bialek" wrote in message
...


Hello, and they are most certainly not "electric" waves.

For the all Fathers of the radio they are the electric waves.
You wrote: "Hams have designed and constructed novel and practical
antennas over the years but their explanations about how they work are
often just plain wrong."

Could you give as the correct explanation?
S*

Hello Szczepan.

We've tried to assist you but you seem to prefer to stay with 19th century
knowledge rather than learn modern knowledge. If you ask for help and don't
accept the answers you get then there's not a lot we can do ... other than
disregard your postings and go and operate our radio stations.

You need to get a modern textbook on radio theory. One suitable for amateur
radio should be okay. Have a look at www.rsgb.org.and www.arrl.org

Kindest regards, Ian.

loop antennas
 

I agree with your second link (by VK1OD).

The time varying magnetic field generates an electric field and that is
received by the loop. When you screen it completely, it doesn't work,
you need the gap.

By placing the gap opposite to the feed point, you get a balanced loop
without the need of ferrite or other constructions. If you can get balance
via other means, you don't need the screen. Balancing the loop reduces
noise due to common mode issues. This isn't different from using a balun
between a coaxial cable and a symmetrical dipole.

Your option three may behave competently different, as the coaxial cable,
power supply cable, switch mode power supply, etc may contribute to
reception of signal and noise due to common mode to differential mode
conversion.

From my experience (reception) with electrically small well-balanced
indoor loops and indoor dipoles, I found some advantage of the loop over
the electric dipole at low frequencies (say below 3 MHz). I contribute
this mainly because of the nulling capability. Whether is applies to your
location depends on the field distribution of the noise at your location.

At higher frequencies there is difference in S/N ratio, but not in favor
of one antenna. Sharp nulling wasn't possible. So to know what option is
best for you, you need to try it. Maybe install both options and select
the antenna that gives best results as this will depend on frequency and
the angle of arrival of the radiation you want to receive.

Other thing that may really help is to find your local source(s) of noise,
use lots of ferrites and try to find a sweet spot for best S/N ratio.

--
Wim
PA3DJS
www.tetech.nl
Please remove abc first in case of PM

So you are saying that cases 1 & 2 above are essentially equvalent if the
loops are balanced. In terms of noise rejection, there is no analogy to be
drawn between a shielded loop and a shielded cable.

loop antennas
 

"Ian" napisa³ w wiadomo¶ci
...
"Szczepan Bialek" wrote in message
...


Hello, and they are most certainly not "electric" waves.

For the all Fathers of the radio they are the electric waves.
You wrote: "Hams have designed and constructed novel and practical
antennas over the years but their explanations about how they work are
often just plain wrong."

Could you give as the correct explanation?
S*

Hello Szczepan.

We've tried to assist you but you seem to prefer to stay with 19th century
knowledge

In 1846 Faraday wrote: "It seems to me, that the resultant of two or more
lines of force is in an apt condition for that action which may be
considered as equivalent to a lateral vibration; whereas a uniform medium,
like the aether, does not appear apt, or more apt than air or water."
http://www.padrak.com/ine/FARADAY1.html

rather than learn modern knowledge.

In 1929 Tesla wrote: " On repeating the Hertz experiments with much improved
and very powerful apparatus, I satisfied myself that what he had observed
was nothing else but effects of longitudinal waves in a gaseous medium, that
is to say, waves, propagated by alternate compression and expansion. He had
observed waves in the ether much of the nature of sound waves in the air."
http://www.tfcbooks.com/tesla/1929-09-22.htm

If you ask for help and don't accept the answers you get then there's not a
lot we can do ... other than disregard your postings and go and operate our
radio stations.

If you have a trouble in explanation about how receiving antennas work use
the Faraday's and Tesla's explanation.

You need to get a modern textbook on radio theory. One suitable for
amateur radio should be okay. Have a look at www.rsgb.org.and www.arrl.org

Is it right?
"Hams have designed and constructed novel and practical
antennas over the years but their explanations about how they work are
often just plain wrong."
S*

loop antennas
 

"Szczepan Bialek" wrote in message
.. .
We've tried to assist you but you seem to prefer to stay with 19th
century
knowledge
In 1846 Faraday wrote:
rather than learn modern knowledge.

Is it right?
"Hams have designed and constructed novel and practical
antennas over the years but their explanations about how they work are
often just plain wrong."
S*

It depends on the individual amateur, doesn't it. That's why we experiment,
write articles, read textbooks and discuss and debate theory and practise.

loop antennas
 

On Friday, June 15, 2012 2:44:39 AM UTC-5, Szczepan Bialek wrote:
Radio waves and light are the oscillatory flow of electrons (L. Lorenz
1869).

Lorenz (and all other physicists and mathematicians) were obviously ignorant of photons in those days. Here is what a more knowledgeable physicist has said more than a century later:

Quoted from: "The Strange Theory of Light and Matter", (c)1985, by Richard P. Feynman

"So now, I present to you the three basic actions, from which all the phenomena of light and electrons arise:

-Action #1: A photon goes from place to place.
-Action #2: An electron goes from place to place.
-Action #3: An electron emits or absorbs a photon."

When Feynman says "light", he is including RF. Photons travel at the speed of light in the medium which is impossible for electrons which possess rest mass. There are no electrons in a pure vacuum, yet light and radio waves pass through it at the speed of light with no problem.

Following your "logic", why go back to 1869? Why not question the periodic table of elements because a few millennia ago, men of science asserted that there are four elements: earth, air, fire, and water. So why not adopt the four element argument as well?
--
73, Cecil, w5dxp.com

loop antennas
 

On 6/15/2012 1:39 PM, W5DXP wrote:
On Friday, June 15, 2012 2:44:39 AM UTC-5, Szczepan Bialek wrote:
Radio waves and light are the oscillatory flow of electrons (L. Lorenz
1869).

Lorenz (and all other physicists and mathematicians) were obviously ignorant of photons in those days. Here is what a more knowledgeable physicist has said more than a century later:

Quoted from: "The Strange Theory of Light and Matter", (c)1985, by Richard P. Feynman

"So now, I present to you the three basic actions, from which all the phenomena of light and electrons arise:

-Action #1: A photon goes from place to place.
-Action #2: An electron goes from place to place.
-Action #3: An electron emits or absorbs a photon."

When Feynman says "light", he is including RF. Photons travel at the speed of light in the medium which is impossible for electrons which possess rest mass. There are no electrons in a pure vacuum, yet light and radio waves pass through it at the speed of light with no problem.

Following your "logic", why go back to 1869? Why not question the periodic table of elements because a few millennia ago, men of science asserted that there are four elements: earth, air, fire, and water. So why not adopt the four element argument as well?
--
73, Cecil, w5dxp.com

Cecil,

I think our Polish friend here is just a troll trying to get attention.

It is a complete waste of time reading his posts, just put him on your
kill list.

In the end for almost all amateur radio operators it does not matter one
wit how an antenna works. It most certainly matters if it works and how
well.

I have used a 75 meter loop antenna here where I live for the past 5
years. It works very well. I live right in town on a lot surrounded by
other homes. I started with a dipole but was advised that a loop would
hear less noise. It turned out to be quite true. I am now a convert to
the loop antenna. Have no idea of the physics of how it works, but it
sure does work well on bands between 75 and 20 meters. It actually seems
to work best on 40 meters.

I don't care about electrons or the names of past pioneers in radio. I
mean no offence to them, I just have moved on since being a child
studying radio.

Michael

loop antennas
 

El 15-06-12 16:09, garyr escribió:
I agree with your second link (by VK1OD).

The time varying magnetic field generates an electric field and that is
received by the loop. When you screen it completely, it doesn't work,
you need the gap.

By placing the gap opposite to the feed point, you get a balanced loop
without the need of ferrite or other constructions. If you can get balance
via other means, you don't need the screen. Balancing the loop reduces
noise due to common mode issues. This isn't different from using a balun
between a coaxial cable and a symmetrical dipole.

Your option three may behave competently different, as the coaxial cable,
power supply cable, switch mode power supply, etc may contribute to
reception of signal and noise due to common mode to differential mode
conversion.

From my experience (reception) with electrically small well-balanced
indoor loops and indoor dipoles, I found some advantage of the loop over
the electric dipole at low frequencies (say below 3 MHz). I contribute
this mainly because of the nulling capability. Whether is applies to your
location depends on the field distribution of the noise at your location.

At higher frequencies there is difference in S/N ratio, but not in favor
of one antenna. Sharp nulling wasn't possible. So to know what option is
best for you, you need to try it. Maybe install both options and select
the antenna that gives best results as this will depend on frequency and
the angle of arrival of the radiation you want to receive.

Other thing that may really help is to find your local source(s) of noise,
use lots of ferrites and try to find a sweet spot for best S/N ratio.

--
Wim
PA3DJS
www.tetech.nl
Please remove abc first in case of PM

So you are saying that cases 1& 2 above are essentially equvalent if the
loops are balanced. In terms of noise rejection, there is no analogy to be
drawn between a shielded loop and a shielded cable.





Hello Gary,

You are right, it is what I am saying.

There is no analogy between the shielding function of the braid in a
coaxial transmission line and the shield in your loop.

For the "shielded" loop, the received voltage is across the gap in the
shield. The shield is the actual single turn loop. The inner
conductor is just there to transport the received signal to the
opposite side of the gap where you can go down (with coaxial cable) to
your receiver, maintaining balance.

Theoretically a coaxial transmission line system is completely closed.
Water from the outside can't reach the inner conductor, source or
load. When cutting a gap in the screen, the coaxial transmission line
system will leak.

Shielded loop with more turns
If you run more turns within the shield of the loop, you pass the gap
many times. When you pass it 3 times, you will get three times the
voltage, hence the impedance and loop inductance increase.

--
Wim
PA3DJS
www.tetech.nl
Please remove abc first in case of PM

loop antennas
 

On 6/15/2012 2:23 PM, Boomer wrote:


I have used a 75 meter loop antenna here where I live for the past 5
years. It works very well. I live right in town on a lot surrounded by
other homes. I started with a dipole but was advised that a loop would
hear less noise. It turned out to be quite true. I am now a convert to
the loop antenna. Have no idea of the physics of how it works, but it
sure does work well on bands between 75 and 20 meters. It actually seems
to work best on 40 meters.

It is not true. Only in the cases of corona buildup, etc, on the
elements would that be the case.
If you hear less noise with the loop, vs the dipole, it's due to
the change in pattern. Not due to any qualities of the loop itself.
Noise is RF the same as any other signal, and follows all the same
rules. It's no different than an actual signal.
If what you/they say is true, and the loop received less noise, it would
also receive less "desired" signals. Or in other words, everything
would be down vs the dipole.
The most likely explanation is the change in pattern less favored
the direction the noise is coming from. Either that, or the noise is
local to your shack, and for some reason the loop's feed line is better
decoupled than the one feeding the dipole.
If I had to bet, I'd say it's the change in pattern.
There are no magical anti noise properties with loops.

loop antennas
 

On Friday, June 15, 2012 4:06:25 PM UTC-5, NM5K wrote:
Only in the cases of corona buildup, etc, on the
elements would that be the case.

He may be talking about precipitation static which was considerably reduced for me in the AZ desert when I converted my dipole to a folded dipole. My problem was dust storms even on a sunny day.

http://www.its.bldrdoc.gov/fs-1037/dir-028/_4096.htm

P-static is unrelated to the reception of EM RF far-field signals. It is a static charge transferred from charged particles in the air directly to an antenna. It was so bad in AZ that arcing occurred at my coax connector. I have actually seen the p-static envelope on my IC-756PRO's display.

The problem with a dipole is that one element of the dipole normally does not have a DC path to ground. When the p-static discharge takes place, it may be through the series capacitor in the receiver. With a loop antenna, including a folded dipole, the p-static usually has a path directly to ground from any point in the antenna system. It's not the only path but it certainly reduces the p-static noise although not completely eliminating it.

Of course, it is possible to reduce the p-static problems on a dipole with a parallel resistor/choke, a 4:1 voltage balun, or heavily insulated wires. Hams who live in low p-static areas of the country will invariably say that there is no such thing because they have never seen it. But hams who have lived in the AZ desert know better.
--
73, Cecil, w5dxp.com

loop antennas
 

On 6/15/2012 6:03 PM, W5DXP wrote:
On Friday, June 15, 2012 4:06:25 PM UTC-5, NM5K wrote:
Only in the cases of corona buildup, etc, on the
elements would that be the case.

He may be talking about precipitation static which was considerably reduced for me in the AZ desert when I converted my dipole to a folded dipole. My problem was dust storms even on a sunny day.

http://www.its.bldrdoc.gov/fs-1037/dir-028/_4096.htm

P-static is unrelated to the reception of EM RF far-field signals. It is a static charge transferred from charged particles in the air directly to an antenna. It was so bad in AZ that arcing occurred at my coax connector. I have actually seen the p-static envelope on my IC-756PRO's display.

The problem with a dipole is that one element of the dipole normally does not have a DC path to ground. When the p-static discharge takes place, it may be through the series capacitor in the receiver. With a loop antenna, including a folded dipole, the p-static usually has a path directly to ground from any point in the antenna system. It's not the only path but it certainly reduces the p-static noise although not completely eliminating it.

Of course, it is possible to reduce the p-static problems on a dipole with a parallel resistor/choke, a 4:1 voltage balun, or heavily insulated wires. Hams who live in low p-static areas of the country will invariably say that there is no such thing because they have never seen it. But hams who have lived in the AZ desert know better.
--
73, Cecil, w5dxp.com

True, but I mentioned that first thing..
"
Only in the cases of corona buildup, etc, on the
elements would that be the case. "

The "etc" including what you are referring to.. I was
just too lazy to include that in the list. :/

But say here in Houston, with the high humidity, we rarely
ever see the type static you had in AZ.
You can also see that in some snow storms from what I hear.

But I mainly want to vote against the idea that a loop, with
no static problems, has the ability to receive less noise as
far as radiated RF from other sources.
It's one of those myths "as far as I'm concerned" that needs
to be put out of it's misery.
For instance, some will claim a small shielded loop that is
indoors, will receive less noise than an equal size unshielded
loop in the same location. Have never seen that to be the
case here, when comparing them. In fact, both the loops I kept
for permanent use were regular old unshielded diamond loops.
The biggest being the PVC frame loop that is 44 inches per side
as I recall.. I have another one that is a circular loop about
16 inches dia. The large one is 7 turns. The small one I think 12
or so.
I tried using shielded loops, but the performance was the
same. I also tried using shielded loops as the coupling loop
inside the larger unshielded loop. Worked fine, but no better
than an unshielded coupling loop with no balance problems.
I kept the shielded coupling loop for the small loop, but
used plain wire on the large one. It was easier to thread
through the spreaders, and also lighter.

loop antennas
 

On 6/15/2012 4:06 PM, NM5K wrote:
On 6/15/2012 2:23 PM, Boomer wrote:


I have used a 75 meter loop antenna here where I live for the past 5
years. It works very well. I live right in town on a lot surrounded by
other homes. I started with a dipole but was advised that a loop would
hear less noise. It turned out to be quite true. I am now a convert to
the loop antenna. Have no idea of the physics of how it works, but it
sure does work well on bands between 75 and 20 meters. It actually seems
to work best on 40 meters.

It is not true. Only in the cases of corona buildup, etc, on the
elements would that be the case.
If you hear less noise with the loop, vs the dipole, it's due to
the change in pattern. Not due to any qualities of the loop itself.
Noise is RF the same as any other signal, and follows all the same
rules. It's no different than an actual signal.
If what you/they say is true, and the loop received less noise, it would
also receive less "desired" signals. Or in other words, everything
would be down vs the dipole.
The most likely explanation is the change in pattern less favored
the direction the noise is coming from. Either that, or the noise is
local to your shack, and for some reason the loop's feed line is better
decoupled than the one feeding the dipole.
If I had to bet, I'd say it's the change in pattern.
There are no magical anti noise properties with loops.



I understand that my experience contravenes your theories about how
antennas should work.

I had several local hams suggest that I use a loop after I kept
complaining about noise. I finally put it up. It is more difficult to
erect than a simple dipole. It is at the same height as was my dipole 35
feet.

The receiver noise level dropped dramatically. I was so glad I went to
the trouble to do it. I finally took down my dipole after switching back
and forth for a year just to be sure the dipole was not better in some
circumstance.

The other effect was an immediate increase in the signal received by my
friends who live within about 200 miles. We operate at 3913. I could not
figure this out until I consulted a pdf file about antennas. The 75
meter loop has a 9 dbi gain at the optimum height of 25 feet. Mine is a
bit high but still gets some gain. All my friends reported on this
increase in my output signal. This information can be found at
http://www.hamuniverse.com/n4jaantennabook.html

This configuration is basically a NVIS antenna. It works so much better
than did my dipole. It gets pretty good dx on 40 and 20. I use an Imax
2000 for 15 and 10.

So, I and my friends know that this antenna works better than a dipole
by actually using it for several years. One of the hams in our group has
been using a loop hung from 2 200 foot towers in a vertical position. He
has done extensive experimentation over the last 45 years.

And yes, a 75 meter loop at 35 feet above ground has a different pattern
than a dipole. I don't care why it works better at all. I and others
just know that it works better and with less noise than a dipole.

And no, a loop antenna is not magic. It is different than a dipole.
Different types of antennas behave differently. The worst antenna I hear
on the air comes from people using G5RVs. Their signal is just totally
lame when they use the recommended 80 foot dipole on 75 meters. If they
would just extend that same antenna to 120 feet they would do so much
better.

Sorry my loop works so well.

Michael

loop antennas
 

On 6/15/2012 4:06 PM, NM5K wrote:
On 6/15/2012 2:23 PM, Boomer wrote:


I have used a 75 meter loop antenna here where I live for the past 5
years. It works very well. I live right in town on a lot surrounded by
other homes. I started with a dipole but was advised that a loop would
hear less noise. It turned out to be quite true. I am now a convert to
the loop antenna. Have no idea of the physics of how it works, but it
sure does work well on bands between 75 and 20 meters. It actually seems
to work best on 40 meters.

It is not true. Only in the cases of corona buildup, etc, on the
elements would that be the case.
If you hear less noise with the loop, vs the dipole, it's due to
the change in pattern. Not due to any qualities of the loop itself.
Noise is RF the same as any other signal, and follows all the same
rules. It's no different than an actual signal.
If what you/they say is true, and the loop received less noise, it would
also receive less "desired" signals. Or in other words, everything
would be down vs the dipole.
The most likely explanation is the change in pattern less favored
the direction the noise is coming from. Either that, or the noise is
local to your shack, and for some reason the loop's feed line is better
decoupled than the one feeding the dipole.
If I had to bet, I'd say it's the change in pattern.
There are no magical anti noise properties with loops.




Here is quote from N4JA's informative antenna book.

......XIV. ONE-WAVELENGTH SINGLE LOOP ANTENNAS


1. The Horizontally Oriented Loop


To calculate the length in feet of any one-wavelength loop, divide 1005
by the frequency in MHz. Horizontally oriented one-wavelength loop
antennas have become very popular on 160, 80, and 40 meters and it is
one type of NVIS antenna. (NVIS stands for "near vertical incidence
skywave" because of its high angle radiation pattern.) It is claimed by
its users that the loop antenna is quieter than other antennas. This is
because it doesnt pick up the noise from power lines, thunderstorms,
etc., coming in at low angles. These antennas radiate on their
fundamental frequencies with a broad pattern straight up to put a strong
signal for nearby contacts. Recently published articles on this type of
antenna have called them "cloud warmers." There are other types of
antennas called NVIS antennas other than loops. They are dipoles at low
heights or dipoles with parasitic reflectors placed under them to cause
the signal to radiate mostly straight up. The NVIS antennas have an
advantage in working nearby stations because you dont get the static
noise and interference from far distances. They are definitely not DX
antennas. An article on NVIS antennas appears in the December 2005 QST......

loop antennas
 

On 6/15/2012 7:23 PM, Boomer wrote:

If I had to bet, I'd say it's the change in pattern.

An article on NVIS antennas appears in the December 2005
QST......



I guess my hunch on the difference being pattern related
panned out.. :)
I've used horizontal loops on the low bands. But I came to the
conclusion they were generally not worth the extra trouble, vs
a dipole. I could barely see any difference here from the usual
dipoles I ran. And if the signal is stronger at one angle or direction,
vs another antenna, it's weaker in another. So it's all a compromise.

On the low bands, I came to the conclusion my favorite antenna for
mostly NVIS and medium path work was the turnstile.
Which are crossed dipoles. You can feed them in or out of phase
for either dipole patterns, or with them 90 degrees out of phase,
for a fairly round omnidirectional pattern.
I like to do well to the close in stations, but also the ones
farther off too.. So even if I used a loop, I would generally
try to get it as high as possible.
Which I also do using dipoles, or turnstiles.

loop antennas
 

"Wimpie" wrote in message
el.net...
El 15-06-12 16:09, garyr escribió:
I agree with your second link (by VK1OD).

The time varying magnetic field generates an electric field and that is
received by the loop. When you screen it completely, it doesn't work,
you need the gap.

By placing the gap opposite to the feed point, you get a balanced loop
without the need of ferrite or other constructions. If you can get
balance
via other means, you don't need the screen. Balancing the loop reduces
noise due to common mode issues. This isn't different from using a balun
between a coaxial cable and a symmetrical dipole.

Your option three may behave competently different, as the coaxial
cable,
power supply cable, switch mode power supply, etc may contribute to
reception of signal and noise due to common mode to differential mode
conversion.

From my experience (reception) with electrically small well-balanced
indoor loops and indoor dipoles, I found some advantage of the loop over
the electric dipole at low frequencies (say below 3 MHz). I contribute
this mainly because of the nulling capability. Whether is applies to
your
location depends on the field distribution of the noise at your
location.

At higher frequencies there is difference in S/N ratio, but not in favor
of one antenna. Sharp nulling wasn't possible. So to know what option
is
best for you, you need to try it. Maybe install both options and select
the antenna that gives best results as this will depend on frequency and
the angle of arrival of the radiation you want to receive.

Other thing that may really help is to find your local source(s) of
noise,
use lots of ferrites and try to find a sweet spot for best S/N ratio.

--
Wim
PA3DJS
www.tetech.nl
Please remove abc first in case of PM

So you are saying that cases 1& 2 above are essentially equvalent if the
loops are balanced. In terms of noise rejection, there is no analogy to
be
drawn between a shielded loop and a shielded cable.





Hello Gary,

You are right, it is what I am saying.

There is no analogy between the shielding function of the braid in a
coaxial transmission line and the shield in your loop.

For the "shielded" loop, the received voltage is across the gap in the
shield. The shield is the actual single turn loop. The inner conductor is
just there to transport the received signal to the opposite side of the
gap where you can go down (with coaxial cable) to your receiver,
maintaining balance.

Theoretically a coaxial transmission line system is completely closed.
Water from the outside can't reach the inner conductor, source or load.
When cutting a gap in the screen, the coaxial transmission line system
will leak.

Shielded loop with more turns
If you run more turns within the shield of the loop, you pass the gap many
times. When you pass it 3 times, you will get three times the voltage,
hence the impedance and loop inductance increase.

--
Wim
PA3DJS
www.tetech.nl
Please remove abc first in case of PM

Wim,

Thanks very much for your lucid explanation of how shielded loops function.
I've been using one with a receiver I made to monitor VLF signals. It works
quite well and I had thought it was because of all the local noise I was
avoiding. But then I stumbled across VK1OD's article...

Best regards,
Gary Richardson, AA7VM

PS
Thanks also to all the other respondents. This has been a very interesting
thread.

loop antennas
 

On Wed, 13 Jun 2012 15:11:06 -0700, "garyr" wrote:

This site http://www.frontiernet.net/~jadale/Loop.htm states that: "A
properly designed Loop primarily responds to the magnetic component of the
radio wave. Note that noise resides primarily in the electrical
component..."

Whereas this site shows that that is not the case:
http://vk1od.net/antenna/shieldedloop.

So what is the advantage, if any, of a shielded loop antanna?

Consider three receivers:

1) Shielded loop antenna, receiver with differential input (center-tapped
transformer or instrumentation amp). The two ends of the inner conductor
of the antenna connected to the differential inputs and the shield
connected to ground.

2) Same as above but without the shield.

3) Unshielded loop antenna, receiver with single-ended input.
One end of the loop connected to the receiver input and the other to
ground.

Assuming equal gains and bandwidths, would there be any
difference in the sensitivity or noise level at the output of the three
receivers?

A loop is a loop is a loop, meaning that one side conductor goes
upwards while the other side goes downwards in contrast to a
linear wire antenna or a dipole which is extending in one direction
only. The up-and down (left and right) parts of the wire cancel out
each other at least partially when collecting energy from an electric
field, while the energy uptake from a magnetic field is proportional
to the loop area.
This electric noise cancellation is not perfect, due to unsymmetries
in the field, therefore it pays to shield the loop wires and decrease
the electric influences further.

I hope my explanation is simple enough.

w.

loop antennas
 

"W5DXP" napisal w wiadomosci
...
On Friday, June 15, 2012 2:44:39 AM UTC-5, Szczepan Bialek wrote:
Radio waves and light are the oscillatory flow of electrons (L. Lorenz
1869).

Lorenz (and all other physicists and mathematicians) were obviously
ignorant of photons in those days. Here is what a more knowledgeable
physicist has said more than a century later:

Quoted from: "The Strange Theory of Light and Matter", (c)1985, by Richard
P. Feynman

Feynman has been called the "Great Explainer".[22] He gained a reputation
for taking great care when giving explanations to his students and for
making it a moral duty to make the topic accessible. His guiding principle
was that if a topic could not be explained in a freshman lecture, it was not
yet fully understood. Feynman gained great pleasure[23] from coming up with
such a "freshman-level" explanation". The below is the example:

"So now, I present to you the three basic actions, from which all the
phenomena of light and electrons arise:

-Action #1: A photon goes from place to place.
-Action #2: An electron goes from place to place.
-Action #3: An electron emits or absorbs a photon."

When Feynman says "light", he is including RF. Photons travel at the speed
of light in the medium which is impossible for electrons which possess rest
mass. There are no electrons in a pure vacuum, yet light and radio waves
pass through it at the speed of light with no problem.

Feynman was a teacher. The scientists were the opposite opinion:

"
In 1900, Max Planck was working on black-body radiation and suggested that
the energy in electromagnetic waves could only be released in "packets" of
energy. In his 1901 article [4] in Annalen der Physik he called these
packets "energy elements". The word quanta (singular quantum) was used even
before 1900 to mean particles or amounts of different quantities, including
electricity. Later, in 1905 Albert Einstein went further by suggesting that
electromagnetic waves could only exist in these discrete wave-packets.[5] He
called such a wave-packet the light quantum (German: das Lichtquant). The
name photon derives from the Greek word for light, ??? (transliterated
phôs), and was coined[Note 1] in 1926 by the physical chemist Gilbert Lewis,
who published a speculative theory in which photons were "uncreatable and
indestructible".[6] Although Lewis' theory was never accepted as it was
contradicted by many experiments, his new name, photon, was adopted
immediately by most physicists. Isaac Asimov credits Arthur Compton with
defining quanta of energy as photons in 1923."[7][8]

For scientists the photon is like the tone in sound.

In the pure vacuum are electrons. Do not you know about the Dirac electron
sea?

S*


Following your "logic", why go back to 1869? Why not question the periodic
table of elements because a few millennia ago, men of science asserted that
there are four elements: earth, air, fire, and water. So why not adopt the
four element argument as well?
--
73, Cecil, w5dxp.com

loop antennas
 

Szczepan Bialek wrote:
Feynman was a teacher. The scientists were the opposite opinion:

Were. In 1900. But now it is 2012.

loop antennas
 

"Szczepan Bialek" wrote in message
...

In the pure vacuum are electrons. Do not you know about the Dirac
electron
sea?

S*

Hello Szczepan.
Can you explain the Dirac electron sea in simple terms, please?

Regards, Ian.

loop antennas
 

On Saturday, June 16, 2012 3:12:44 AM UTC-5, Szczepan Bialek wrote:
In the pure vacuum are electrons. Do not you know about the Dirac electron
sea?

Yes, I know about it but Dirac nor anyone else who matters has claimed that electrons can travel at the speed of light. The thing that travels at the speed of light has been proven to be quantized, i.e. to consist of discrete packets or particles. It has been 84 years since Dirac came up with his theory. It is now generally accepted that Dirac's "sea of electrons" is made up of something other than electrons, i.e. dark matter/energy, in a quantum structure which results in the Casimir effect.

Here's the problem with a "sea of electrons" or virtual particles to explain the quantum structu

http://science.nasa.gov/astrophysics...s-dark-energy/

"But when physicists tried to calculate how much energy this would give empty space, the answer came out wrong - wrong by a lot. The number came out 10120 times too big. That's a 1 with 120 zeros after it. It's hard to get an answer that bad. So the mystery continues."

loop antennas
 

"W5DXP" napisal w wiadomosci
...
On Saturday, June 16, 2012 3:12:44 AM UTC-5, Szczepan Bialek wrote:
In the pure vacuum are electrons. Do not you know about the Dirac
electron
sea?

Yes, I know about it but Dirac nor anyone else who matters has claimed that
electrons can travel at the speed of light.

For Faraday, Lorenz and Tesla the light and radio waves are exactly like the
sound.
So we must distinguish the speed of the light and the speed of the particles
of the medium.
For Faraday, Lorenz and Tesla the medium is the plasma (ions + electrons).

So the key issue is if "In the pure vacuum are electrons". Are they?

?The thing that travels at the speed of light has been proven to be
quantized, i.e. to consist of discrete packets or particles. It has been 84
years since Dirac came up with his theory. It is now generally accepted that
Dirac's "sea of electrons" is made up of something other than electrons,
i.e. dark matter/energy, in a quantum structure which results in the Casimir
effect.

Here's the problem with a "sea of electrons" or virtual particles to explain
the quantum structu

http://science.nasa.gov/astrophysics...s-dark-energy/

"But when physicists tried to calculate how much energy this would give
empty space, the answer came out wrong - wrong by a lot. The number came out
10120 times too big. That's a 1 with 120 zeros after it. It's hard to get an
answer that bad. So the mystery continues."

The "electron waves" or oscillatory flow of electrons is simply seen in the
crystal radio and rectennas.
But everybody prefer "So the mystery continues."
S*

loop antennas
 

Szczepan Bialek wrote:

Feynman was a teacher.

Richard Feynman was a Ph.D. in physics and, among other awards, won a
Nobel Prize in Physics (1965) for his theory of quantum electrodynamics.

The scientists were the opposite opinion:

The scientists in 1900 had different opinions, but by Feynman's time
everyone knew better.

You are apparently the only one who hasn't yet learned.

You are a babbling idiot.

loop antennas
 

Szczepan Bialek wrote:


For Faraday, Lorenz and Tesla the light and radio waves are exactly like the
sound.

And they were wrong and you are an idiot.

loop antennas
 

"Rob" wrote in message
...
Szczepan Bialek wrote:
Feynman was a teacher. The scientists were the opposite opinion:

Were. In 1900. But now it is 2012.


Everyone's attempts to reason with Snicklefritz Dingle )
will come to naught. It reminds me of a joke:


A farmer was having a hard time with his new mule. The stubborn mule
wouldn't take the harness. Reluctantly, he hired a mule-trainer, who
arrived promptly the next morning.

The mule-trainer picked up a sledgehammer and slammed the mule between the
eyes. The mule staggered backwards from the blow.

"Hey," screamed the farmer, "I don't want you to kill my mule!"

"Relax, pal." replied the mule-trainer. "Before you can train 'em, you have
to get their attention."


In my considered opinion, nobody really has Snicklefritz's attention.

"Sal"

loop antennas
 

In message , Boomer
writes



The worst antenna I hear on the air comes from people using G5RVs.
Their signal is just totally lame when they use the recommended 80 foot
dipole on 75 meters. If they would just extend that same antenna to 120
feet they would do so much better.

The full-size G5RV is 102' (not 80'), and works pretty well as a
shortish halfwave on 80m. The half-size is 51', and is intended for 40m
and above. However, although maybe not the antenna of choice, with a
tuner and 450 or 600 ohm twin feeder it should be possible to make even
an 80' dipole work fairly effectively on 80m.

One amateur (local to me), who I believe has limited space, reckons that
a straight, short dipole works better than a squeezed-in, dog-legged
full-size dipole. I think his is 85', and it certainly works well on
80m.




--
Ian

loop antennas
 

On Saturday, June 16, 2012 12:15:34 PM UTC-5, Szczepan Bialek wrote:
The "electron waves" or oscillatory flow of electrons is simply seen in the
crystal radio and rectennas. But everybody prefer "So the mystery continues."

If empty space were filled with a "sea of electrons", their combined massive gravity would have an observable effect but actual gravity calculations prove that the "sea of electrons" cannot exist. You are correct about there being a medium through which EM waves flow, but it is impossible for it to consist of any form of known visible matter. Exactly what it consists of is still a mystery.

If empty space were filled with electrons, we would be able to measure the drag caused by the electrons. Any known particle of matter with a rest mass would cause a drag on movement of matter through it.

You remind me of the story of the man who is looking under the street light for his lost keys even though he lost them a block away. His explanation was, "I'm looking for my keys here because the light is better."
--
73, Cecil, w5dxp.com

loop antennas
 

On 6/16/2012 2:19 PM, Ian Jackson wrote:
In message , Boomer
writes



The worst antenna I hear on the air comes from people using G5RVs.
Their signal is just totally lame when they use the recommended 80
foot dipole on 75 meters. If they would just extend that same antenna
to 120 feet they would do so much better.

The full-size G5RV is 102' (not 80'), and works pretty well as a
shortish halfwave on 80m. The half-size is 51', and is intended for 40m
and above. However, although maybe not the antenna of choice, with a
tuner and 450 or 600 ohm twin feeder it should be possible to make even
an 80' dipole work fairly effectively on 80m.

One amateur (local to me), who I believe has limited space, reckons that
a straight, short dipole works better than a squeezed-in, dog-legged
full-size dipole. I think his is 85', and it certainly works well on 80m.





On 160m, I had better luck using a full size "Z" dipole than
I did shorter dipoles that were loaded with high Q coils.

I sort of agree with him about the G5RV, but it's the feed that
is the problem, not the length of the radiator. Generally too much
feedline loss with the way most people run them. Same problem with
many of the various commercial Windoms that they sell.

I prefer the full length dipoles because it's easy to feed them in
a low loss manner. On the low bands, it's very hard to beat a dipole
fed with coax for overall system efficiency. Maybe nearly impossible,
being as I've never found anything more efficient so far.
I suppose a tuned feeder of ladder line would be as good, "IE: the Cecil
method" but not nearly as convenient.
I never could match coax performance using ladder line and a tuner.
Close, but not quite.. No matter how careful setting the tuner using
the very minimum of inductance.

I guess that's why I'm such a coax fan... May not be good for multi-
band use with a single dipole, but for single or limited band use, very
hard to beat.

I remember one year I got stuck using some kind of Windom for 80 and 40
at field day.
It was terrible... I swore never, ever again..
But sure nuff.. The next year they tried to stick me on a windom again.
But I was ready.. :) I brought everything I needed to make a dipole
on site. Which I did. I then whipped out a coax switch so I could
A/B the two antennas, just to prove I wasn't barking at the moon.
When you switched to the coax fed dipole, *everything* jumped up
at least full 2 S units on his rig. His eyes got big as saucers.
He never really suspected he was losing that much.
Needless to say, I stayed on the coax fed dipole.
The RF mayhem of field day is no time to be using lossy compromise
antennas.. I never could see that, when you have enough room to
use just about anything.

loop antennas
 

On Saturday, June 16, 2012 2:48:21 PM UTC-5, NM5K wrote:
I guess that's why I'm such a coax fan... May not be good for multi-
band use with a single dipole, but for single or limited band use, very
hard to beat.

Here's one that will beat most RG-8x fed dipoles.

http://www.w5dxp.com/notuner.htm
--
73, Cecil, w5dxp

loop antennas
 

On 6/16/2012 3:21 PM, W5DXP wrote:
On Saturday, June 16, 2012 2:48:21 PM UTC-5, NM5K wrote:
I guess that's why I'm such a coax fan... May not be good for multi-
band use with a single dipole, but for single or limited band use, very
hard to beat.

Here's one that will beat most RG-8x fed dipoles.

http://www.w5dxp.com/notuner.htm
--
73, Cecil, w5dxp

I use 213 though... :) Your method is about the only other one
I can think of that should be as good. On paper, slightly less
loss than the coax, but being I've never compared them side by
side, I couldn't say if your method is actually superior enough
to see a difference on a meter.. I've never tried your method of
feeding. The physical aspects are not too convenient for me most
of the time.
In the case of the ladder line/tuner vs coax, the difference was
small, but enough to notice a bit of difference on an S meter.
Of course, I'm using received signals to judge. Things should be
reciprocal, so I usually don't bother trying to do transmit tests
as I consider it less reliable than quick A/B comparisons and my
eyes on a meter.
Good ladder line is generally less loss than good coax, but on the
low bands, the loss per foot of good coax is pretty low.
I would think the advantage to your system would increase as you
rise in frequency. IE: at 50 Mhz, might be quite worthwhile.. Or if
long runs are involved. When I ran ATV on 70 cm, I preferred TV twin
lead over coax for the UHF TV antenna I used for receive.
It had less loss than coax to a 4:1 TV balun. As long as it was dry..
Wet? Nearly useless... :(

loop antennas
 

"W5DXP" napisal w wiadomosci
...
On Saturday, June 16, 2012 12:15:34 PM UTC-5, Szczepan Bialek wrote:
The "electron waves" or oscillatory flow of electrons is simply seen in
the
crystal radio and rectennas. But everybody prefer "So the mystery
continues."

If empty space were filled with a "sea of electrons", their combined
massive gravity would have an observable effect but actual gravity
calculations prove that the "sea of electrons" cannot exist. You are
correct about there being a medium through which EM waves flow, but it is
impossible for it to consist of any form of known visible matter. Exactly
what it consists of is still a mystery.

All physisists (not teachers) are opinion that in space is enough matter to
propagate the electric waves.

If empty space were filled with electrons,

In "empty space" is ISM (interstellar medium = ions, electrons and dust)

we would be able to measure the drag caused by the electrons. Any known
particle of matter with a rest mass would cause a drag on movement of
matter through it.

Michelson discovered in 1887 and 1925 that ISM rotate with the Sun and do
not rotate with the Earth.
Meteorologists know that above the equator is steady wind caused by ISM.
In the rest of the globe the winds are caused by many factors.

You remind me of the story of the man who is looking under the street light
for his lost keys even though he lost them a block away. His explanation
was, "I'm looking for my keys here because the light is better."

Michael wrote: "In the end for almost all amateur radio operators it does
not matter one
wit how an antenna works. It most certainly matters if it works and how
well."

But the all of you are "the infinite sink" of the real information for me.
Not all Amateur radio operators are teachers.
Faraday and Marconi did not go to schools.
S*