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

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

Of course. To me, this proves my point about the antenna in itself. But
again, I don't
consider adding decoupling as making an antenna or even antenna system
"low noise".
That might be an end result to a guy with loads of local noise, but to
a guy in the woods,
it means nada...His noise level in the woods should still be the same.

As far as #1,
1/4 wave Marconi mono-pole electric field sensitive unbalanced., as
being a worst case,
I would think that depends on how it's set up. IE: grounded at the
base, radials, etc as
John mentioned...I never run "incomplete" antennas. Ever...
My 1/4 wave's are not overly prone to common mode problems, but as I
mentioned, if I use a
1/4 wave, it would be properly installed with the lower "half" of the
antenna included,
either as radials, or at least grounded. A balanced coax fed dipole can
be quite bad, if the operation
of the choke, balun, etc is not functioning properly. This would
usually show up more on bands higher
than it's half wave length. IE: Using a 40 meter dipole on 20 meters,
etc..With the hi Z feed on
20m, a usual 1:1 balun would be fairly useless as far as decoupling the
feedline. MK

BTW, if the type on these post's gets goofy, it's cuz I'm using the new
google "beta" and the line wrapping
has changed, and is driving me nuts...It wants to run off the page
forever, unless I manual hit return, and that
drives me crazy. The "old" google, auto wrapped as you typed. Why do
they always
have to mess up something that works perfectly well as is....Or
was...Overall, I don't
like this new google beta much at all.

"N",

Its about 'effective communication' as John Doty posted earlier
in this thread.

The average Shortwave Listener (SWL) who owns a Shortwave Radio
and WANTS More-Out-of-It; simply wants to 'know':

- What to Buy and How to Put It Up.

- Or - What to Build and How to Do It.

- NO Rhyme-or-Reason is Required [.]
[ Please - Just Tell Me - What To Do ]


1. So 'suggesting' they Buy a PAR End Fed Shortwave Listener
(EF-SWL) Antenna and 'configuring' the Antenna in the [Shape]
of an Inverted "L" Antenna.

PAR Electronics "End Fed Shortwave Listener" (EF-SWL) Antenna
POPCOM= http://www.popular-communications.co...landOct04.html
MT= http://www.monitoringtimes.com/html/mt2003reviews.html
eHAM= http://www.eham.net/reviews/detail/3707
PAR= http://www.parelectronics.com/swl_end.htm
UR= http://www.universal-radio.com/catalog/sw_ant/2205.html
GE= http://www.grove-ent.com/ANT8.html

Telling the SWL 'what-to-do' in general simple terms.
http://tinyurl.com/66lhs
http://tinyurl.com/683gd
http://tinyurl.com/4qmqw


2. Or simply 'recommending' that they READ three WebPages
to gain some understanding of the "Low Noise" SWL Antenna.
http://tinyurl.com/4kp7m

CONSIDER BUILDING A "LOW NOISE" ANTENNA:
Try building an Improved SWL Random Wire Antenna that uses a
9:1 Matching Transformer (Balun / MLB) then you may not see
any real 'improvement' in your receive signal.
This is the so called "Low Noise" SWL Antenna.
Three "Must" Links to Read -wrt- Low Noise SWL Antenna
http://groups.yahoo.com/group/Shortw...na/message/949
[ Please READ These Three Links ]
http://www.anarc.org/naswa/badx/ante...e_antenna.html
http://www.anarc.org/naswa/badx/ante..._longwire.html
http://www.anarc.org/naswa/badx/antennas/grounding.html
ABOUT THE "LOW NOISE" ANTENNA 'DESIGN CONCEPTS':
A Random Wire Antenna Element coupled via a 9:1 Matching
Transformer at the Near-End of the Antenna with a Ground
Rod and Coax Cable Feed-in-Line to the Receiver. This is
the basic SWL Antenna that uses the "Low Noise Antenna"
'design concepts' that were {popularized} by John Doty.
..
..
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. ]
..
..

RHF wrote:
"N",

Its about 'effective communication' as John Doty posted earlier
in this thread.

I think I've fairly well communicated my thoughts on the matter...
Thats all I intended to do. But it seems some have problems with even
that..
Every time I post something here, I get a load of @$#^$*%('s climbing
down my back. Get over it! If you disagree with something I say, fine.
I have
no problems with that. But to harp just because I won't dumb myself
down to
your "supposed" r.r.s.w. monkey level status, really starts to grate on
my nerves.

The average Shortwave Listener (SWL) who owns a Shortwave Radio
and WANTS More-Out-of-It; simply wants to 'know':

I'm not an "average" shortwave listener, and I don't claim to cater to
them.
Actually, I don't claim to cater to anyone....It's not my job.

- What to Buy and How to Put It Up.

That will stir more conflict than this thread....:/

- Or - What to Build and How to Do It.

I think the user should decide that. Not some guy 1000 or more miles
away...
Only he knows what he really wants or needs..I have no problems telling

someone how to build something, but for the most part, it's all been
covered a
zillion times over...Thats why they sell books. Thats why I have books.


- NO Rhyme-or-Reason is Required [.]

I can't live that way myself. I refuse to be "dumbed down" to trained
monkey
level, just because this is a shortwave listeners group. If I get too
technical for some,
"which I really don't think I do", or I get anal retentive because
people
keep calling certain antennas "low noise", they can just ignore it.
Many people *do* want
to know the truth,or maybe a little more detail about certain things.
They may not reply
to any of the posts.
Many people read the stuff,that never actually post. It's not like I
use a bunch of
fancy named mumbo jumbo, or obtuse theories designed to confuse people.
If they want to
call them "lower noise antenna systems", I'd have less problem with
that. But as I
said, I don't consider simply decoupling a feedline as making it a "low
noise" antenna
system. Even if that could be the end result for some. It's just acting
normally without
the common currents screwing up the operation.
If you take a milked down stock 302 ford engine with say 150 hp when
running
normally, and 2 plugs are fouled, allowing only 110 hp out, changing
all the plugs
does not make the engine a blueprinted 400 hp race engine. It will now
run properly with
the new plugs, but it will still be the same stock 150 hp engine. This
probably won't make much sense
to you, but that's a fairly fitting analogy I think...
The decoupled antenna system is just acting normally. The un-decoupled
antenna system
is not. It's a defective system. It would be more accurate to call such
a system a "high noise" system, than
it is to call the decoupled system "low noise". Or to me anyway...
I just want to make sure people understand that the lower noise they
experience
is due to decoupling the feedline from the antenna, and has nothing to
do with
the antenna itself. I'm sure many already realize this. But it seems
fairly obvious many
don't. I'm also sure not *everyone* wants to live in the dark like a
mushroom.
I make no apologies for being anal retentive. That is my job.




[ Please - Just Tell Me - What To Do ]

Why? It's not my job....:/ You should already be fairly well set up
anyway
judging from all the links you post ...

MK

MK,

All of what you have written defines You 'being' YOU !
{and that is Good}

All of what I have written defines Me 'being' ME !
{and that is Good}
..
i guess we are communicating - pal ~ RHF
..
..

Guys Guys - there is both room for, and value in, both approaches.

I'm glad that both of you post here. Keep those antenna tips coming!
Bruce Jensen

"bpnjensen" wrote in message
oups.com...
Guys Guys - there is both room for, and value in, both approaches.

I'm glad that both of you post here. Keep those antenna tips
coming!

Which reminds me....

I was perusing the ground articles in hard-core-dx.com,
and I was curious about one of the articles there (probably
was one of John's) stating that a good way of eliminating
common mode interference is to ground the shield separately
away from the 9:1 transformer. That I can do easily, but I
was curious about the next statement about attaching the
ground directly to the shield.

My thinking is that it would be smarter to attach the ground
to the shield via a ground block, but the only ground blocks
I can find use the F connectors, not the 239/259 ones. Is it
necessarily a good idea to strip the coating off the coax,
exposing the shield, and clamping that shield to the ground
rod? Seems like you'd be exposing the connection to the
elements, probably hastening the demise of the coax at that
point. Not to mention the changing of the interaction of
the two conductors by changing it's form...

--Mike L.

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

Of course. To me, this proves my point about the antenna in itself. But
again, I don't
consider adding decoupling as making an antenna or even antenna system
"low noise".
That might be an end result to a guy with loads of local noise, but to
a guy in the woods,
it means nada...His noise level in the woods should still be the same.

As far as #1,
1/4 wave Marconi mono-pole electric field sensitive unbalanced., as
being a worst case,
I would think that depends on how it's set up. IE: grounded at the
base, radials, etc as
John mentioned...I never run "incomplete" antennas. Ever...
My 1/4 wave's are not overly prone to common mode problems, but as I
mentioned, if I use a
1/4 wave, it would be properly installed with the lower "half" of the
antenna included,
either as radials, or at least grounded. A balanced coax fed dipole can
be quite bad, if the operation
of the choke, balun, etc is not functioning properly. This would
usually show up more on bands higher
than it's half wave length. IE: Using a 40 meter dipole on 20 meters,
etc..With the hi Z feed on
20m, a usual 1:1 balun would be fairly useless as far as decoupling the
feedline. MK

BTW, if the type on these post's gets goofy, it's cuz I'm using the new
google "beta" and the line wrapping
has changed, and is driving me nuts...It wants to run off the page
forever, unless I manual hit return, and that
drives me crazy. The "old" google, auto wrapped as you typed. Why do
they always
have to mess up something that works perfectly well as is....Or
was...Overall, I don't
like this new google beta much at all.