John Doty's noise reducing antenna ideas from his 1993 posting are virtually
identical to noise reducimg antenna ideas found in articles by Denzil
Wraight and me which were published in DX News in 1991. Denzil's article
was titled "Interference Reducing Antennas For The BCB," and mine was
"Inverted L Noise Reducing MF/VLF Antenna." Denzil and I used twinlead
rather than coax. However, Mark Connelly published descriptions of similar
noise reducinmg antennas using coax in DX News later in 1991. These
articles are available from The National Radio Club http://www.nrcdxas.org/
as reprint A69. Contrary to what John claims, these kinds of noise reducing
antennas are not very effective against noise at SW frequencies much above 6
MHz. These types of noise reducing antennas were invented by F. R. W.
Strafford in or about 1936, and he discusses these and other types of noise
reducing antennas for short waves in "Screened Aerials," Wireless World,
November 25, 1937, pages 516 - 518.

Best regards,

Dallas

DALLAS {aka: AEN} ,

Long ago John Doty corrected me on the 'fact' that he did not "Invent"
these Antennas or the Design Concepts of these Low Noise Antennas.

However, within this Forum {Rec.Radio.Shortwave} his 'articles'
{Writings} and his 'name' are/is the most often cited reference
concerning this topic.

This is why I say {write}
"Low Noise SWL Antenna" using the 'design concepts' that were
popularized by John Doty.

READ - Three "Must" Links to Read -wrt- Low Noise SWL Antenna
http://groups.yahoo.com/group/Shortw...na/message/949

NOTE: John Doty's 'articles' {Writings} and his 'name' are/is
available freely on the Web (WWW) and thus Millions may View and Read
them.

AEN - ? Have you consider 're-printing' your 'articles' {Writings} on
the Web (WWW) and making them Free for All to View and Read ?

AEN - Doing so, may provide you with the recognition that you so justly
deserve.

TBL: As to whether, the "Low Noise" Antenna 'design concepts' work
well for Shortwave Listener (SWL) Antennas: They have improved my
Shortwave Listening with good signal levels and much lower noise. What
more can I say: "I Ain't No Elmer !"

Enjoy Listening to your Radio/Receivers with your Antennas.

iane ~ RHF
..
All are WELCOME at the Shortwave Listener (SWL) "Antenna Ashram"
http://groups.yahoo.com/group/Shortw...na/message/502
Some Say: On A Clear Day You Can See Forever.
I BELIEVE: On A Clear Night . . .
You Can Hear Forever and Beyond, The BEYOND !
[ With the a SWL Antenna of your own making. ]
..
..

Hi whatever your name is,

I am puzzled. If, as you wrote, John corrected you on the 'fact' that he
did not "Invent" these Antennas or the Design Concepts of these Low Noise
Antennas, then presumably he told you who did. So why have he and you
neglected to mention that in your writings?

It was Denzil Wraight, in fact, who rediscovered Strafford's work on noise
reducing antennas, and who discovered by trial and error reasonable turns
ratios for the antenna matching transformers (Strafford does not discuss
that in his articles). So it is Strafford and Wraight that Doty plagiarized
and you failed to cite. Denzil used a vertical noise reducing antenna,
wrote me about how well it worked, and included a copy of Strafford's
Wireless World article. First I constructed a "top fed" vertical version
with mast almost touching my house. I didn't expect it to do much fow man
made noise in the MW band (my main interest), but to my surprise it did. In
my case, there was little, if any, difference noise reduction between
mounting the vertical mast almost touching my house, or 100 feet away. So
this kind of noise reducing antenna is ideal for DXers with limited space.
Next I implemented an inverted L version of Strafford's noise reducing
antennas. If I recall correctly, the first L was about 100 feet horizontal
and 15 feet vertical. I experimented with both base feed and top feed.
Both gave excellent noise reduction in the MW (and VLF) band(s). Both
Denzil and I used twin feed instead of coax because twin feed tends to pick
up less local nois than coax. Denzil and I wrote two separate articles for
DX news (The National Radio Club http://www.nrcdxas.org/ reprint A69) that
were published in the early summer of 1991. I had sent Mark Connelly
preprints of our arfticles, and he developed coax feed versions of
Strafford's noise reducing antennas. According to Mark, the coax feed
variant picked up little, if any additional noise compared to the twin feed
version. At one point in these experiments I tried shielded twin lead, but
found no further noise reduction (or increase).

Presently I use top fed inverted L noise reducing antennas as parts of my
phased arrays. Unless you are listening above 16 MHz or so, or have an
insensitive receiver, you don't really need (or want) a big inverted L. Mine
are 15 feet up and 30 feet horizontal. The matching transformer we
used then (and which I still use now) is an Amidon FT-114-75 (the 75
material may have been replaced with J material), 43 turns to 9 turns (at
the center of the 43 turns) #20 enameled copper wire. The twin lead I still
use is Radio Shack speaker wire (#18 stranded, 7 strands of, I think, #26).
It is cheaper ane easier to use than real twin lead, and had about the right
characteristic impedance (about 100 ohms). You'll need a balun (1:1) at
your receiver to convert the balanced lead in to your unbalanced receiver
antenna input (9 bifilar turns of #20 enameled on an FT-114-75 will do).

Like I said before, the noise reducing properties of these kinds of antennas
begin to decline as you go higher in frequency, and above 6 MHz there is not
much noise reduction. If you believe you got substantial noise reduction
above 6 MHz due only to using one of these kinds of antennas, then you are
mistaken. For SW, Strafford recommended doublet antennas for noise
reduction. I do not have much experience with these because I am not much
of a SW listener. What little experience I have suggests that phased arrays
are much more effective at reducing SW noise sources. Unfortunately,there
are no good phasers that you can buy.

As for publishing these articles on the web, that would involve considerable
work. The articles were produced with typewriters, and contain hand
drawings. To convert them to .PDF or other files would be non-trivial, and
would require NRC approval. Anyone who wants these articles can easily
purchase them as reprints from the NRC at the web site above using PayPal or
other methods of payment.

Best regards,

Dallas

"RHF" wrote in message
oups.com...
DALLAS {aka: AEN} ,

Long ago John Doty corrected me on the 'fact' that he did not "Invent"
these Antennas or the Design Concepts of these Low Noise Antennas.

However, within this Forum {Rec.Radio.Shortwave} his 'articles'
{Writings} and his 'name' are/is the most often cited reference
concerning this topic.

This is why I say {write}
"Low Noise SWL Antenna" using the 'design concepts' that were
popularized by John Doty.

READ - Three "Must" Links to Read -wrt- Low Noise SWL Antenna
http://groups.yahoo.com/group/Shortw...na/message/949

NOTE: John Doty's 'articles' {Writings} and his 'name' are/is
available freely on the Web (WWW) and thus Millions may View and Read
them.

AEN - ? Have you consider 're-printing' your 'articles' {Writings} on
the Web (WWW) and making them Free for All to View and Read ?

AEN - Doing so, may provide you with the recognition that you so justly
deserve.

TBL: As to whether, the "Low Noise" Antenna 'design concepts' work
well for Shortwave Listener (SWL) Antennas: They have improved my
Shortwave Listening with good signal levels and much lower noise. What
more can I say: "I Ain't No Elmer !"

Enjoy Listening to your Radio/Receivers with your Antennas.

iane ~ RHF
.
All are WELCOME at the Shortwave Listener (SWL) "Antenna Ashram"
http://groups.yahoo.com/group/Shortw...na/message/502
Some Say: On A Clear Day You Can See Forever.
I BELIEVE: On A Clear Night . . .
You Can Hear Forever and Beyond, The BEYOND !
[ With the a SWL Antenna of your own making. ]
.
.

In article .com,
"RHF" wrote:

DALLAS {aka: AEN} ,

Long ago John Doty corrected me on the 'fact' that he did not "Invent"
these Antennas or the Design Concepts of these Low Noise Antennas.

Snip

Scientists and engineers have been pondering electromagnetism, antennas
and transmission lines for a century so it's hard to come up with
something new.

--
Telamon
Ventura, California

Some of Dallas' excellent articles are indeed on the Web. Check out
http://www.kongsfjord.no and look under the section "The Dallas Files".

I particularly have benefited from his review and mods for the ICOM
IC-746Pro, as it helped me in my decision to buy and modify a IC-756Pro
(which as very similar receive circuitry).

Guy Atkins
Puyallup, WA USA


"RHF" wrote in message
oups.com...

SNIP

AEN - ? Have you consider 're-printing' your 'articles' {Writings} on
the Web (WWW) and making them Free for All to View and Read ?

SNIP

Alfred E. Newman wrote:
Hi whatever your name is,

I am puzzled. If, as you wrote, John corrected you on the 'fact' that he
did not "Invent" these Antennas or the Design Concepts of these Low Noise
Antennas, then presumably he told you who did. So why have he and you
neglected to mention that in your writings?

RHF can't tell you because I didn't tell him. I didn't tell him because
I don't know. I know that the principles behind this kind of system were
well understood by radio engineers 70 years ago. I don't know the
original sources.

The idea of using a transmission line to prevent EMI pickup goes back at
least to 1877. According to the February 19, 1881 issue of Scientific
American, the US patent office ruled (in a dispute with Alexander Graham
Bell) that David Brooks had invented the "return wire" as a way to
reduce crosstalk between telegraph and telphone lines (and if someone
were to cite earlier work by, say, Kelvin, I wouldn't be surprised).


It was Denzil Wraight, in fact, who rediscovered Strafford's work on noise
reducing antennas, and who discovered by trial and error reasonable turns
ratios for the antenna matching transformers (Strafford does not discuss
that in his articles). So it is Strafford and Wraight that Doty plagiarized
and you failed to cite.

I've never heard of either of these people. My approach is apparently
more theoretical: if you understand the physics you don't need to
experiment with turns ratios (it's a "back of the envelope"
calculation). My writing is my own, not copied from anyone. The design
itself is a combination of well known ideas that should be obvious to an
expert: that makes it engineering, not invention.

Denzil used a vertical noise reducing antenna,
wrote me about how well it worked, and included a copy of Strafford's
Wireless World article. First I constructed a "top fed" vertical version
with mast almost touching my house. I didn't expect it to do much fow man
made noise in the MW band (my main interest), but to my surprise it did. In
my case, there was little, if any, difference noise reduction between
mounting the vertical mast almost touching my house, or 100 feet away. So
this kind of noise reducing antenna is ideal for DXers with limited space.
Next I implemented an inverted L version of Strafford's noise reducing
antennas. If I recall correctly, the first L was about 100 feet horizontal
and 15 feet vertical. I experimented with both base feed and top feed.
Both gave excellent noise reduction in the MW (and VLF) band(s). Both
Denzil and I used twin feed instead of coax because twin feed tends to pick
up less local nois than coax.

If you're getting less pickup with twin lead than coax, there's
something amiss with the way you're using the coax. In general, coax
picks up much less than twinlead. The EM field of coax is confined
within the cable. The field of twinlead surrounds the cable, making it
much more susceptible to to external coupling.

Denzil and I wrote two separate articles for
DX news (The National Radio Club http://www.nrcdxas.org/ reprint A69) that
were published in the early summer of 1991. I had sent Mark Connelly
preprints of our arfticles, and he developed coax feed versions of
Strafford's noise reducing antennas. According to Mark, the coax feed
variant picked up little, if any additional noise compared to the twin feed
version. At one point in these experiments I tried shielded twin lead, but
found no further noise reduction (or increase).

I got to know Mark a few years after I wrote the article. His approach
is similar to mine, but there are some important differences. He uses
transformers for isolation as well as matching. I shunt the common mode
current to ground at the ground stakes, while absorbing the common mode
energy by burying the coax between them.

Mark never accused me of intellectual theft.


Presently I use top fed inverted L noise reducing antennas as parts of my
phased arrays. Unless you are listening above 16 MHz or so, or have an
insensitive receiver, you don't really need (or want) a big inverted L. Mine
are 15 feet up and 30 feet horizontal. The matching transformer we
used then (and which I still use now) is an Amidon FT-114-75 (the 75
material may have been replaced with J material), 43 turns to 9 turns (at
the center of the 43 turns) #20 enameled copper wire. The twin lead I still
use is Radio Shack speaker wire (#18 stranded, 7 strands of, I think, #26).
It is cheaper ane easier to use than real twin lead, and had about the right
characteristic impedance (about 100 ohms). You'll need a balun (1:1) at
your receiver to convert the balanced lead in to your unbalanced receiver
antenna input (9 bifilar turns of #20 enameled on an FT-114-75 will do).

Like I said before, the noise reducing properties of these kinds of antennas
begin to decline as you go higher in frequency, and above 6 MHz there is not
much noise reduction. If you believe you got substantial noise reduction
above 6 MHz due only to using one of these kinds of antennas, then you are
mistaken. For SW, Strafford recommended doublet antennas for noise
reduction. I do not have much experience with these because I am not much
of a SW listener. What little experience I have suggests that phased arrays
are much more effective at reducing SW noise sources. Unfortunately,there
are no good phasers that you can buy.

I measured 36 dB of EMI reduction at 25 MHz with one of my antennas. If
you're not getting good EMI reduction at SW there's some important
difference between your approach and mine.


As for publishing these articles on the web, that would involve considerable
work. The articles were produced with typewriters, and contain hand
drawings. To convert them to .PDF or other files would be non-trivial, and
would require NRC approval. Anyone who wants these articles can easily
purchase them as reprints from the NRC at the web site above using PayPal or
other methods of payment.

The trouble is that most people who are interested will never even know
what to order. Allowing your work to be freely published on the web is a
good way to get it circulated. Credit for ideas tends to flow to those
whose disseminate them, regardless of precedence or the desires of the
people involved.


Best regards,

Dallas

-jpd

dallas, Dalas. DALLAS !

"RHF" are my 'initials' and for most of my work life I was "RHF"

DALLAS - Now I say that "I am a Work-A-Holic in Recovery;
Living Retired, Healthy and Free in OK-Land, Cali-4-Ni-A."
- "RadioHighFreq" on Yahoo eGroups.
- "Retired-Health-and-Free" on eBay.
- My eMail Address for Rec.Radio.Shortwave is

Anyone what to guess what my initials are ? ? ?

DALLAS ? So tell me Dallas why do you post here as "Alfred E. Newman"
?


DALLAS - Here is what John Doty 'posted' :
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - - - -
John Doty Jan 11, 2004 @ 7:35 pm show options
Newsgroups: rec.radio.shortwave
From: (John Doty)
Date: 11 Jan 2004 19:35:33 -0800
Local: Sun, Jan 11 2004 7:35 pm
Subject: N8KDV Random Wire Antennas -&- N8KDV Ten-to-One (10:1)
Matching Transformer
Reply | Reply to Author | Forward | Print | Individual Message | Show
original | Report Abuse


N8KDV wrote in message

...
Also, I'm afraid to point out that the
design pre-dates the John Doty concept. (as far as I know).


True. There was nothing really new in my design. I wrote up the design
because I hadn't seen a good clear explanation of nonresonant wire
antennas with effective common mode decoupling. The article has been
posted on several web sites and published in several newsletters:
people seem to find it helpful. But it doesn't represent an invention,
it's just a piece of writing.

John Doty
"You can't confuse me,
but an unreliable news server can make posting difficult!"
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - - - -

DALLAS - Here is my 'reply'
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - - - -
RHF Jan 12, 2004 @ 1:47 am show options
Newsgroups: rec.radio.shortwave
From: (RHF)
Date: 12 Jan 2004 01:47:14 -0800
Local: Mon, Jan 12 2004 1:47 am
Subject: N8KDV Random Wire Antennas -&- N8KDV Ten-to-One (10:1)
Matching Transformer
Reply | Reply to Author | Forward | Print | Individual Message | Show
original | Report Abuse

JPD,

I guess I will have to to change my attribution line.

FROM: Low Noise Antenna Design Concepts
- written by John Doty

TO: Low Noise Antenna Design Concepts
- as popularized by the writings of John Doty

http://www.anarc.org/naswa/badx/ante...e_antenna.html

Build-It-YourSelf and Hear the Difference.
From the Association of North American Radio Clubs (ANARC) WebSite
and the Rec.Radio.ShortWave (NG) WebPage.

IMHO: No one can deny that your Writings about the Low Noise Antenna
Design Concepts have 'helped' to "Popularize" those design concepts.

iane ~ RHF
..
..
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - - - -

About "POPULARIZE" : Legendary "Henry Ford" may not have invented or
engineered
the Automobile; but no one can dispute that he was a prime figure in
POPULARIZING
the Automobile in the USofA by making a 'basic and reliable'
Automobiles like the
Model "A" and "T that were Economically Affordable for many Americans.

One could make the same statement about Bill Gates and MicroSoft;
MS-DOS
and Windows.

DALLAS - I Remain 'rhf' ~ RHF - aka - a Really Happy Fella )
..
..

Alfred E. Newman wrote:

John Doty's noise reducing antenna ideas from his 1993 posting are virtually
identical to noise reducimg antenna ideas found in articles by Denzil
Wraight and me which were published in DX News in 1991.

Decoupling a feedline is decoupling a feedline....

Denzil's article
was titled "Interference Reducing Antennas For The BCB," and mine was
"Inverted L Noise Reducing MF/VLF Antenna."

Is that an oximoron? Seriously...Using an omnidirectional antenna to
reduce *noise* on those bands is kinda counterproductive seems to me...

Denzil and I used twinlead
rather than coax. However, Mark Connelly published descriptions of similar
noise reducinmg antennas using coax in DX News later in 1991. These
articles are available from The National Radio Club http://www.nrcdxas.org/
as reprint A69. Contrary to what John claims, these kinds of noise reducing
antennas are not very effective against noise at SW frequencies much above 6
MHz.

Uhh...Decoupling a feedline is decoupling a feedline. No matter what
frequency...
You can do it at 440 mhz just fine... All my antennas are well
decoupled, and that includes from MW to 440 mhz.


These types of noise reducing antennas were invented by F. R. W.
Strafford in or about 1936, and he discusses these and other types of noise
reducing antennas for short waves in "Screened Aerials," Wireless World,
November 25, 1937, pages 516 - 518.

Decoupling the feedline has been around for quite a while...
I guess I have one issue though, and yes, I am anal retentive...I object
to *any* antenna being called a "low noise" antenna. Why? Cuz they don't
exist. These is no such thing. They should describe all of these types
of decoupled antenna schemes as "examples of better decoupled antenna
*systems*. The lower noise has nothing to do with the antenna itself.
Only the decoupling of the line, coax or ladder line. And to top this
off, if you are in a quiet area with no noise to pickup, using the
decoupling schemes will not do *anything* at all to reduce noise. The
performance will be exactly the same. IE: out in the woods, running
battery power, etc...A *true* noise reducing *antenna* would work
anywhere, but again, as far as I'm concerned, they don't exist. The on;y
way to really reduce noise using the antenna itself, would be to change
polarity. That would reduce an opposite polarized signal about 20 db or
so...
As far as the decoupling losing effectiveness over a certain freq, thats
a design issue with the decoupling scheme being used. Balun, chokes,
etc...BTW...I include the so called "shielded loops" with the "misnamed"
antenna group. In all tests I've ever run, I've never seen any
indication a shielded loop is any *quieter* to noise pickup than a
regular open loop. But the reason there is not due to decoupling of the
feedline per say, although a lack of decoupling can effect the overall
balance. It's due to the shielded loop providing inherent good balance
due to it's design. But if you have an open loop just as well balanced,
it will null noise sources just as well as a shielded loop. A shielded
loop is not any quieter to far field noise, than any other loop if you
are not using it to null the noise source. It *could* do a better job of
nulling that source, *if* the balance on the open loop was poorer, but
again, this is a design issue..You can design the open loop to be just
as balanced. MK

--
http://web.wt.net/~nm5k

Mark Keith wrote:

I guess I have one issue though, and yes, I am anal retentive...I object
to *any* antenna being called a "low noise" antenna. Why? Cuz they don't
exist. These is no such thing. They should describe all of these types
of decoupled antenna schemes as "examples of better decoupled antenna
*systems*.

One trouble is that many potential readers wouldn't understand such a
pedantic article title.

The lower noise has nothing to do with the antenna itself.
Only the decoupling of the line, coax or ladder line.

You can't decouple the line from an unbalanced antenna that lacks a
counterpoise. You can argue that really isn't an antenna (and I would
agree!), but such things are sold as "antennas". The most commonly
recommended "antenna" for the newbie is a "random wire", technically
only half of an unbalanced dipole. Even professionals aren't immune from
this technical error: unbalanced dipoles are often called "monopoles"
even though Maxwell's equations forbid a true monopole antenna.

Even if a counterpoise is present, the design of the antenna influences
your ability to effectively decouple it from the line. Ungrounded but
unsymmetrical antennas (like "slopers") are particularly troublesome.

And to top this
off, if you are in a quiet area with no noise to pickup, using the
decoupling schemes will not do *anything* at all to reduce noise. The
performance will be exactly the same. IE: out in the woods, running
battery power, etc...A *true* noise reducing *antenna* would work
anywhere, but again, as far as I'm concerned, they don't exist.

In the article in question, I wrote, "The real trick with a shortwave
receiving antenna system is to keep your receiver from picking up noise
from all the electrical and electronic gadgets you and your neighbors
have". Plainly, I was not talking about receiving systems out in the woods.

I'm a professional physicist: I can be as fussy and pedantic as you'd
like. Unfortunately, that rarely leads to effective communication. SWL's
write to me to tell me that following my advice has improved their
reception, and several DX websites host copies of my article. I like to
think that shows I've communicated something that matters to people. You
seem to know quite a bit about this stuff: why not write up *your*
approach to these issues?

-jpd

In article , Mark Keith wrote:

Alfred E. Newman wrote:

John Doty's noise reducing antenna ideas from his 1993 posting are virtually
identical to noise reducimg antenna ideas found in articles by Denzil
Wraight and me which were published in DX News in 1991.

Decoupling a feedline is decoupling a feedline....

Denzil's article
was titled "Interference Reducing Antennas For The BCB," and mine was
"Inverted L Noise Reducing MF/VLF Antenna."

Is that an oximoron? Seriously...Using an omnidirectional antenna to
reduce *noise* on those bands is kinda counterproductive seems to me...

Denzil and I used twinlead
rather than coax. However, Mark Connelly published descriptions of similar
noise reducinmg antennas using coax in DX News later in 1991. These
articles are available from The National Radio Club http://www.nrcdxas.org/
as reprint A69. Contrary to what John claims, these kinds of noise reducing
antennas are not very effective against noise at SW frequencies much above 6
MHz.

Uhh...Decoupling a feedline is decoupling a feedline. No matter what
frequency...
You can do it at 440 mhz just fine... All my antennas are well
decoupled, and that includes from MW to 440 mhz.


These types of noise reducing antennas were invented by F. R. W.
Strafford in or about 1936, and he discusses these and other types of noise
reducing antennas for short waves in "Screened Aerials," Wireless World,
November 25, 1937, pages 516 - 518.

Decoupling the feedline has been around for quite a while...
I guess I have one issue though, and yes, I am anal retentive...I object
to *any* antenna being called a "low noise" antenna. Why? Cuz they don't
exist. These is no such thing. They should describe all of these types
of decoupled antenna schemes as "examples of better decoupled antenna
*systems*. The lower noise has nothing to do with the antenna itself.
Only the decoupling of the line, coax or ladder line. And to top this
off, if you are in a quiet area with no noise to pickup, using the
decoupling schemes will not do *anything* at all to reduce noise. The
performance will be exactly the same. IE: out in the woods, running
battery power, etc...A *true* noise reducing *antenna* would work
anywhere, but again, as far as I'm concerned, they don't exist. The on;y
way to really reduce noise using the antenna itself, would be to change
polarity. That would reduce an opposite polarized signal about 20 db or
so...
As far as the decoupling losing effectiveness over a certain freq, thats
a design issue with the decoupling scheme being used. Balun, chokes,
etc...BTW...I include the so called "shielded loops" with the "misnamed"
antenna group. In all tests I've ever run, I've never seen any
indication a shielded loop is any *quieter* to noise pickup than a
regular open loop. But the reason there is not due to decoupling of the
feedline per say, although a lack of decoupling can effect the overall
balance. It's due to the shielded loop providing inherent good balance
due to it's design. But if you have an open loop just as well balanced,
it will null noise sources just as well as a shielded loop. A shielded
loop is not any quieter to far field noise, than any other loop if you
are not using it to null the noise source. It *could* do a better job of
nulling that source, *if* the balance on the open loop was poorer, but
again, this is a design issue..You can design the open loop to be just
as balanced. MK

"...I object to *any* antenna being called a "low noise" antenna. Why?
Cuz they don't exist. These is no such thing."

Low noise antennas exist and one type is a shielded loop. The noise
improvement is from local noise sources not distant radiating far fields.

Inefficiently radiating local noise sources tend to spread out the
electric field where the magnetic field stays closer to the source.
These are induction fields not radiating fields. It is well known that
local noise source problems are due to common mode inductive electric
field pickup.

Mono-poles (Marconi 1/4 wave) and dipoles are examples of voltage
sensitive antennas. Loop or folded dipoles are examples of antennas
more sensitive to magnetic fields than electric.

A Mono-pole is great at picking up common mode electric fields and is
the worst type in noisy areas. It is very insensitive to local magnetic
fields.

Small unshielded loops are good at picking up local magnetic fields and
poor at picking up local electric fields. Shielding the loop makes it
even less sensitive to local electric fields.

Decoupling the unbalanced transmission line allow a balanced antenna to
stay that way. The balanced antenna is less sensitive to local common
mode electric fields.

Decoupling the transmission line helps prevent noise picked up on it's
outer shield from coupling to the antenna or noise from the mains
supply, through the radio and coax from coupling to the antenna.

If you don't live in the woods and if you or your neighbors have
electrically noisy electronic devices that radiate poorly but still
generate spread out electric common mode fields then the worst type to
best type relative to another is:

1. 1/4 wave Marconi mono-pole electric field sensitive unbalanced.

2. 1/2 wave dipole electric field field sensitive balanced antenna.

3. 1 wavelength or larger loop antenna which is a mix of electric and
magnetic field sensitive antenna. This antenna is balanced.

4. 1/10 wave or less loop antenna which is balanced, mostly magnetic
sensitive and has very poor electric field pickup.

5. 1/10 wave or less shielded loop which is generally better balanced
than unshielded and the least sensitive to local noise electric fields.

RELATIVELY SPEAKING "5" is a "low noise" antenna compared to "1" as far
as locally generated noise is concerned.

--
Telamon
Ventura, California