loopantennas : Messages : 6861-6890 of 9941

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Thanks,
Steve Greenfield

Reply | Messages in this Topic (89)

#6863

From: Chris Trask <christrask@...>
Date: Sun Nov 1, 2009 2:35 pm
Subject: Re: Feed impedance and filtering for a small receiving loop antenna

chris3trask

>
> So here is my thought - use 16:1 balun to transform the loop's
> basic feed impedance closer to 50 ohms, then feed through a high
> pass filter with cutoff ~3 MHz (to reduce AM BC band signals but
> minimize impact on 80M and above signals), then a wideband mmic
> amp (50 ohms in/out, ~20 dB gain) to drive signal back to shack
> receiver.
>
> Is this a reasonable way to approach this? Other ideas, resources,
> suggestions or comments would really be appreciated.
>

      I did an extensive amount of impedance measurements for loop antennas some
time ago, which were then used for a series of receiving and transmitting
antenna designs.  One of the designs, which is remotely tuned using a pair of
varactors, is at:

      http://www.home.earthlink.net/~christrask/Paper011.html

and an indoor version is at:

      http://www.home.earthlink.net/~christrask/Paper018.html

      You'll notice that the loop impedance can be seen as a resistor in series
with an inductor, plus a parallel-resonant RLC network if you encroach upon the
first resonance.  For wideband usage, an acive loop antenna is pretty much
limited to interfacing with a high input impedance amplifier as the first stage,
which is not going to make your AM BCB station interferance problem any easier.

      I did make an attempt at wideband passive matching of loop antennas, which
is at:

      http://www.home.earthlink.net/~christrask/Paper010.html

where you can see that the potential for a passive solution is not on the
horizon.  One possible solution is to use an active negative inductor, but I
have yet to come up with a design that is suitable for applications such as
this.

>
> By the way, this is the URL of the original antenna I built, and
> the basis for the idea to build a version that has high pass filter
> between the loop and the amplifier:
>
> http://www.qrss.thersgb.net/active-loop-receiving-antenna.html
>

      John's design is a useful and practical approach to wideband loop antennas,
however the high amplifier input impedance makes any filtering difficult.  You
could try implementing a balanced filter section between the antenna and the
amplifier:

      O--- C ------- C ---O
                |
                |
Antenna        L        Amplifier
                |
                |
      O--- C ------- C ---O



Chris

      ,----------------------.       High Performance Mixers and
     /    What's all this     \    Amplifiers for RF Communications
    / extinct stuff, anyhow?  /
    \  _______,--------------'           Chris Trask / N7ZWY
   _ |/                                  Principal Engineer
  oo\                                  Sonoran Radio Research
(__)\       _                             P.O. Box 25240
   \  \    .'  `.                     Tempe, Arizona 85285-5240
    \  \  /      \
     \  '"        \                 IEEE Senior Member #40274515
      .       (  ) \
       '-| )__| :.  \              Email: christrask@...
         | |  | | \  '.       http://www.home.earthlink.net/~christrask
        c__; c__;  '-..'>.__

                        Graphics by Loek Frederiks

#6864

From: "Dave" <wa4qal@...>
Date: Sat Oct 31, 2009 7:14 pm
Subject: Re: Small loop antenna !!!!!

wa4qal

--- In loopantennas@yahoogroups.com, "gmcjetpilot" <gmcjetpilot@...> wrote:
>
> Good tip! Aluminum bike rim. I will definitely look into that.

Don't forget Copper tubing from the plumbing section of the local
home improvement store.  You can go with the soft-drawn and shape
it into any shape you like, or you can go with the hard-drawn and
use elbows to put it together.

> The only down side of the rim may be EYE appeal, may be? It might look great,
even paint it black. I have the antenna police in my HOA "Home Owner
Association" controlled neighborhood. (Last time I buy a new house with HOA).
Because of the by-laws I can put up an antenna that is 1 METER or less in dia,
so 27" is perfect. The rule is no doubt for Dish antennas, but I am going to
push it. Let them sue me. I don't have my ham but I'll get it. Than I claim Fed
immunity.
>
> I still don't want to push it too much, so I need to make it as "stealth" and
"Pro" looking as I can. I think painting it black would be cool.
>
> The idea of a strip of aluminum rolled onto a hoop might work?
>
> I found professional aluminum hoops used by performing artist (e.g., circus)
were about $50 each. I was also thinking of a plastic hoop (like a hula hoop but
thicker walled) and running a wire in it, preferably Litz wire.

You can do that with Copper plumbing tubing, too.  Just make sure
it's not an electrically complete circle, since that would act as a
shorted turn.

Dave

Reply | Messages in this Topic (6)

#6865

From: david feldman <wb0gaz@...>
Date: Sun Nov 1, 2009 6:45 pm
Subject: Re: Feed impedance and filtering for a small receiving loop antenna

dgfaa

Chris, thank you *very* much for passing along your papers; I'll read them
carefully. I had thought about a varactor tuned loop (and picked up some diodes
this last spring) but didn't explore further at the time, so this will certainly
be helpful to understand.

I'll post back any results once I can get some experimentation underway.

Thanks again very much,

73 Dave WB0GAZ wb0gaz@...

###

> 3c. Re: Feed impedance and filtering for a small receiving loop antenna
> Posted by: "Chris Trask" christrask@... chris3trask
> Date: Sun Nov 1, 2009 6:35 am ((PST))
>
>
>>
>> So here is my thought - use 16:1 balun to transform the loop's
>> basic feed impedance closer to 50 ohms, then feed through a high
>> pass filter with cutoff ~3 MHz (to reduce AM BC band signals but
>> minimize impact on 80M and above signals), then a wideband mmic
>> amp (50 ohms in/out, ~20 dB gain) to drive signal back to shack
>> receiver.
>>
>> Is this a reasonable way to approach this? Other ideas, resources,
>> suggestions or comments would really be appreciated.
>>
>
> I did an extensive amount of impedance measurements for loop antennas some
time ago, which were then used for a series of receiving and transmitting
antenna designs. One of the designs, which is remotely tuned using a pair of
varactors, is at:
>
> http://www.home.earthlink.net/~christrask/Paper011.html
>
> and an indoor version is at:
>
> http://www.home.earthlink.net/~christrask/Paper018.html
>
> You'll notice that the loop impedance can be seen as a resistor in series with
an inductor, plus a parallel-resonant RLC network if you encroach upon the first
resonance. For wideband usage, an acive loop antenna is pretty much limited to
interfacing with a high input impedance amplifier as the first stage, which is
not going to make your AM BCB station interferance problem any easier.
>
> I did make an attempt at wideband passive matching of loop antennas, which is
at:
>
> http://www.home.earthlink.net/~christrask/Paper010.html
>
> where you can see that the potential for a passive solution is not on the
horizon. One possible solution is to use an active negative inductor, but I have
yet to come up with a design that is suitable for applications such as this.
>
>>
>> By the way, this is the URL of the original antenna I built, and
>> the basis for the idea to build a version that has high pass filter
>> between the loop and the amplifier:
>>
>> http://www.qrss.thersgb.net/active-loop-receiving-antenna.html
>>
>
> John's design is a useful and practical approach to wideband loop antennas,
however the high amplifier input impedance makes any filtering difficult. You
could try implementing a balanced filter section between the antenna and the
amplifier:
>
> O--- C ------- C ---O
> |
> |
> Antenna L Amplifier
> |
> |
> O--- C ------- C ---O
>
>
>
> Chris
>

_________________________________________________________________
Windows 7: It works the way you want.
http://www.microsoft.com/Windows/windows-7/default.aspx?ocid=PID24727::T:WLMTAGL\
:ON:WL:en-US:WWL_WIN_evergreen2:112009

#6866

From: Marc Coevoet <sintsixtus@...>
Date: Sun Nov 1, 2009 8:23 pm
Subject: Shortwave schedules, new for the winter, and more info

markov035

Hello,

I put all links together here:

http://users.fulladsl.be/spb13810/radio/

( http://users.fulladsl.be/spb13810/ is the same file)


recently added sites:


So you can select an hour and see which broadcasts start then...

Choose an hour and see transmissions that start in that hour.
GMT Time. 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21
22 23
Not yet a "What's On Shortwave Now Guide", but will come!
http://users.fulladsl.be/spb13810/radio/timelistaoki/

Now with TX Power and location, from other source. Shortwave listings of
300+ languages: English, Deutsch, Francais, Nederlands, Chinese, Russian,
Persian, Swahili, Esperanto, Latin, ....
http://users.fulladsl.be/~spb13810/radio/swlistaoki/


Now with TX Power and location, from other source. Listings of 700+
International Radio stations (mostly on Shortwave)
http://users.fulladsl.be/~spb13810/radio/txlistaoki/

--
Shortwave transmissions in English, Francais, Deutsch, Suid-Afrikaans, Urdu,
Cantonese, Greek, Spanish, Portuguese, ...
http://users.fulladsl.be/spb13810/radio/swlist/
Stations list: http://users.fulladsl.be/spb13810/radio/txlist/

Reply | Messages in this Topic (1)

#6867

From: "Hue Miller" <kargo_cult@...>
Date: Sun Nov 1, 2009 10:47 pm
Subject: TL and QL loop

xtemporize

Loop Antenna News and Information ForumThe TL loop antenna is no longer in
production and the link provided, to Quartzlock, provides
an very interesting data sheet
http://www.quartzlock.com/downloads/datasheets/AE30-300_datasheet.pdf
for their product, However, NO PRICE information provided at all, which I think
a very bad sign,
it means I think, "If price is that important to you, look elsewhere, fellow."
Besides, the QL antenna looks not very impressive, certainly nothing impressive
when
compared to, say, the Wellbrook.
I was very pleased to see the RadCom RSGB antenna project link - I had thought
for  a long
time I would have to buy a back issues compilation to find this.
I also wonder if instead of coax output cable, in the interest of maximum noise
rejection,
it would be worthwhile using twinax, or perhaps just doubling 2 coaxes bound
together.
A moderate impedance mismatch, say 2:1, in this application has no bad effects,
I think?
BTW, I note the Grahn ( Deutschland ) loops in the remote located form, do not
work above
4000 kHz, and the one that does tune to 30,000 kHz is a desktop type, not
remotely located.
This is not what most of us are interested in.
-Hue Miller / Newport, Oregon, USA

[Non-text portions of this message have been removed]

Reply | Messages in this Topic (2)

#6868

From: "C. Beijersbergen" <c.beijersbergen@...>
Date: Mon Nov 2, 2009 9:55 am
Subject: Re: TL and QL loop

ts6023

"I was very pleased to see the RadCom RSGB antenna project link - I had thought
for  a long
time I would have to buy a back issues compilation to find this. "

I don't know what you are referring to, did I miss something? Can you give us
the link?

thanks,

Cor Beijersbergen



[Non-text portions of this message have been removed]

Reply | Messages in this Topic (2)

#6869

From: John Hoopes <jdh1812@...>
Date: Tue Nov 3, 2009 12:16 pm
Subject: Re: 30 foot loop antenna

jdh1812

You can twist the wires from you loop to your phono plug. Several turns per inch
should suffice. You should have a nice broad frequency response with that
set-up.
�
John
�


--- On Fri, 10/30/09, Bill McGraw <mcgr3799@...> wrote:


From: Bill McGraw <mcgr3799@...>
Subject: [loopantennas] 30 foot loop antenna
To: loopantennas@yahoogroups.com
Date: Friday, October 30, 2009, 5:55 PM


�



I just taped up a square 30 foot vertical loop on my east office wall, used a
V-cap with it to help tune it but seemed not necessary. It worked nearly as well
as my horizontal 44 foot loop at the ceiling. I don't know why but I haven't
heard any any strong SSB signals on 80 meters in several weeks. 6 MHz stations,
China and Cuba come in strong. I haven't heard anything on 20 meters with this
radio.

Will someone tell me how best to make a lead-in to my radio (RS DX 398)? Can I
just twist some stranded wire together? Do I need to ground the loop? I grounded
the horizontal loop, actually a OCF horizontal loop of sorts, one end to my
outside ground and both ends fed into a sterio 1/8" plug to the radio.

Bill McGraw
"Somewhere South of Chicago"
Greenville, Mississippi



















[Non-text portions of this message have been removed]

Reply | Messages in this Topic (5)

#6870

From: Marc Coevoet <sintsixtus@...>
Date: Wed Nov 4, 2009 9:55 am
Subject: Height versus lenght in loop antennas, and direction.

markov035

Hello:

Suppose the Height/lenght  > 1, will the antenna be more directional
than with a Height/lenght  <1 antenna??


My idea is that n,ow I'm always using a circular loop 35cm/1 feet to 3
feet, 1 meter, and I'm thinking that a square loop/rectangular loop
might be more directive. Would that be true??
(making onde is not such a big work).

BTW: in the ultralightdx group(yahoo), they are using radios with a
silabs chip in it, like the kchoibo kk-S60L, or the tecsun pl-310, that
canb set am narrow/wide to 1, 2, 3, 4 or 6.  Fm is very good too, and
maybe better than the sony digitral hd radio.

Marc
PS/ site renovated with hourly overview of tx on sw!

--
What's on Shortwave guide: choose an hour, go!
http://whatsonshortwave.tk
700+ Radio Stations on SW http://swstations.tk
300+ languages on SW http://radiolanguages.tk

Reply | Messages in this Topic (1)

#6871

From: VK1OO <mike.walkington@...>
Date: Fri Nov 6, 2009 10:14 pm
Subject: What's Better - Faraday Loop or Wire Coupling Loop

mikewalkington

All,

I'm now looking at the coupling loop for my 1.2m diameter 25mm copper
tube loop. Which is better and why - a shielded Faraday Loop or just a
plain wire coupling loop or even a gamma match?  What's the difference
and is there any test reports available measuring and comparing performance?

Mike
VK1OO

#6872

From: "Chris Trask" <christrask@...>
Date: Sat Nov 7, 2009 12:32 am
Subject: Re: What's Better - Faraday Loop or Wire Coupling Loop

chris3trask

>
> I'm now looking at the coupling loop for my 1.2m diameter 25mm copper
> tube loop. Which is better and why - a shielded Faraday Loop or just a
> plain wire coupling loop or even a gamma match?  What's the difference
> and is there any test reports available measuring and comparing
performance?
>

      Many people have becomd frustrated with the difficulty of tuning a loop
with both Faraday loops and Gamma matching.  I decided to try a different
approach using a series of wideband transformers, and the results were
repeatable trouble-free tuning:

     http://www.home.earthlink.net/~christrask/Paper011.html

     http://www.home.earthlink.net/~christrask/Paper012.html

     http://www.home.earthlink.net/~christrask/Paper018.html


Chris

#6873

From: Franco ISØVSU <is0vsu@...>
Date: Sat Nov 7, 2009 4:45 am
Subject: Re: What's Better - Faraday Loop or Wire Coupling Loop

is0vsu

Chris-
thank you for informations. I am building a new loop on these days, and will try
the different approach you suggested.

73

Franco IS0VSU

--- Sab 7/11/09, Chris Trask <christrask@...> ha scritto:

Da: Chris Trask <christrask@...>
Oggetto: Re: [loopantennas] What's Better - Faraday Loop or Wire Coupling Loop
A: loopantennas@yahoogroups.com
Data: Sabato 7 novembre 2009, 01:32







 









       >

> I'm now looking at the coupling loop for my 1.2m diameter 25mm copper

> tube loop. Which is better and why - a shielded Faraday Loop or just a

> plain wire coupling loop or even a gamma match?  What's the difference

> and is there any test reports available measuring and comparing

performance?

>



Many people have becomd frustrated with the difficulty of tuning a loop

with both Faraday loops and Gamma matching.  I decided to try a different

approach using a series of wideband transformers, and the results were

repeatable trouble-free tuning:



http://www.home. earthlink. net/~christrask/ Paper011. html



http://www.home. earthlink. net/~christrask/ Paper012. html



http://www.home. earthlink. net/~christrask/ Paper018. html



Chris

























[Non-text portions of this message have been removed]

#6874

From: "capntripps2000" <capntripps2000@...>
Date: Sat Nov 7, 2009 5:17 am
Subject: Re: What's Better - Faraday Loop or Wire Coupling Loop

capntripps2000

I have used all 4 methods including using the toroid feed.

I've seen no difference between the Faraday shielded feed loop and the bare wire
loop, so I use bare wire loops these days.  The bare wire will handle more power
for continuous duty modes like digital/rtty.  The toroid feed method seems to
overheat with 100watt continuous duty (at least my T240-43 ferrite does).

I've used gamma method and it may actually be the simplest method.

The variable I have noticed that introduces problems is the loop height above
ground.  The lower the loop is to ground the larger the feed loop needs to be. 
I built a 20M loop in the basement and the feedloop was nearly 1/3 the size of
the main loop to achieve a 1:1 SWR when testing.  When I moved the loop to the
attic I needed to reduce the feedloop size to the original 1/5 size in order to
get a 1:1 SWR.
Also, the lower the loop to ground the longer the gamma match feed will be. 
With the toroid feed method you just increase or decrease the number of turns on
the coax side.  I made a toroid matching section with a switch that selects the
turns ratio I need so I can adjust the impedance to match where ever I mount the
loop.

I would go ahead and try the bare wire feedloop first and be ready to change the
loop size and also the shape.  I find I need to compress the feedloop into an
oval to achieve the 'perfect' 1:1 match.

Good luck and happy experimenting!  You will like the loop results!

atd

--- In loopantennas@yahoogroups.com, VK1OO <mike.walkington@...> wrote:
>
> All,
>
> I'm now looking at the coupling loop for my 1.2m diameter 25mm copper
> tube loop. Which is better and why - a shielded Faraday Loop or just a
> plain wire coupling loop or even a gamma match?  What's the difference
> and is there any test reports available measuring and comparing performance?
>
> Mike
> VK1OO
>

#6875

From: "Ken" <faxcap@...>
Date: Mon Nov 9, 2009 4:46 pm
Subject: Loops null direction

mrkeeks

Hi All

I'm looking at a Wellbrook AL-330S. I know they can be mounted on a
rotor and show some rejection. Do they reject when the loop is facing
the noise or on the loops "edge"?

So is it the "O" or the "|" side that rejects?

Thanks
Ken

#6876

From: "EDUARDO" <adcas@...>
Date: Mon Nov 9, 2009 4:57 pm
Subject: Re: Loops null direction

adcasziza

Hello Ken

The side is rejecting this "|", the other side "O" is what makes the best
capture. The band rejection is 80% in the "|".
Respectfully

Eduardo L. Castaldelli
Mairipor�-SP-Brazil
Grid Locator: GG66qq
www.radiodx.qsl.br

   ----- Original Message -----
   From: Ken
   To: loopantennas@yahoogroups.com
   Sent: Monday, November 09, 2009 2:46 PM
   Subject: ***SPAM*** [loopantennas] Loops null direction


   Hi All

   I'm looking at a Wellbrook AL-330S. I know they can be mounted on a
   rotor and show some rejection. Do they reject when the loop is facing
   the noise or on the loops "edge"?

   So is it the "O" or the "|" side that rejects?

   Thanks
   Ken



   ------------------------------------

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   Post files here. If the file comes from a website, please put it in the Links
rather than uploading the file.
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   And please trim all this when replying!Yahoo! Groups Links




[Non-text portions of this message have been removed]

#6877

From: "jaafes" <jaafes@...>
Date: Mon Nov 9, 2009 6:00 pm
Subject: Re: Loops null direction

jaafes

Are you sure,Eduardo?
Jose


--- In loopantennas@yahoogroups.com, "EDUARDO" <adcas@...> wrote:
>
> Hello Ken
>
> The side is rejecting this "|", the other side "O" is what makes the best
capture. The band rejection is 80% in the "|".
> Respectfully
>
> Eduardo L. Castaldelli
> Mairipor�-SP-Brazil
> Grid Locator: GG66qq
> www.radiodx.qsl.br
>
>   ----- Original Message -----
>   From: Ken
>   To: loopantennas@yahoogroups.com
>   Sent: Monday, November 09, 2009 2:46 PM
>   Subject: ***SPAM*** [loopantennas] Loops null direction
>
>
>   Hi All
>
>   I'm looking at a Wellbrook AL-330S. I know they can be mounted on a
>   rotor and show some rejection. Do they reject when the loop is facing
>   the noise or on the loops "edge"?
>
>   So is it the "O" or the "|" side that rejects?
>
>   Thanks
>   Ken
>
>
>
>   ------------------------------------

#6878

From: "EDUARDO" <adcas@...>
Date: Mon Nov 9, 2009 7:03 pm
Subject: Re: Re: Loops null direction

adcasziza

I'm sorry, I did a reversal of position, but to be sure, see the drawing.
Small loop antennas have patterns opposite those of large loops. The minima, or
nulls, are perpendicular to the plane of de loop, while the maxima are off the
ends. Figure shows the directions of maximum and minimum response. The loop
antenna is viewed from above. the nulls (dotted lines ) are orthogonal to the
loop axis, while the maxima are along the loop axis

Att,

Eduardo L. Castaldelli
Mairipor�- SP- Brasil
Grid Locator: GG66qq
www.radiodx.qsl.br

   ----- Original Message -----
   From: jaafes
   To: loopantennas@yahoogroups.com
   Sent: Monday, November 09, 2009 4:00 PM
   Subject: ***SPAM*** [loopantennas] Re: Loops null direction

   Are you sure,Eduardo?
   Jose

   --- In loopantennas@yahoogroups.com, "EDUARDO" <adcas@...> wrote:
   >
   > Hello Ken
   >
   > The side is rejecting this "|", the other side "O" is what makes the best
capture. The band rejection is 80% in the "|".
   > Respectfully
   >
   > Eduardo L. Castaldelli
   > Mairipor�-SP-Brazil
   > Grid Locator: GG66qq
   > www.radiodx.qsl.br
   >
   >   ----- Original Message -----
   >   From: Ken
   >   To: loopantennas@yahoogroups.com
   >   Sent: Monday, November 09, 2009 2:46 PM
   >   Subject: ***SPAM*** [loopantennas] Loops null direction
   >
   >
   >   Hi All
   >
   >   I'm looking at a Wellbrook AL-330S. I know they can be mounted on a
   >   rotor and show some rejection. Do they reject when the loop is facing
   >   the noise or on the loops "edge"?
   >
   >   So is it the "O" or the "|" side that rejects?
   >
   >   Thanks
   >   Ken
   >
   >
   >
   >   ------------------------------------

   ------------------------------------

   If you've got links, post them in the Links section!
   http://groups.yahoo.com/group/loopantennas/links

   Post files here. If the file comes from a website, please put it in the Links
rather than uploading the file.
   http://groups.yahoo.com/group/loopantennas/files

   You can now view images at higher resolution in Photos. Upload JPG and GIF
into Photos. Please convert BMP or TIF to JPG or GIF before uploading.
   http://ph.groups.yahoo.com/group/loopantennas/photos

   And please trim all this when replying!Yahoo! Groups Links

[Non-text portions of this message have been removed]

#6879

From: "EDUARDO" <adcas@...>
Date: Mon Nov 9, 2009 7:16 pm
Subject: Re: Re: Loops null direction

adcasziza

See de picture!

Respectfully,

Eduardo L. Castaldelli
  Mairipor�-SP-Brazil
Grid Locator: GG66qq
www.radiodx.qsl.br

----- Original Message -----
   From: jaafes
   To: loopantennas@yahoogroups.com
   Sent: Monday, November 09, 2009 4:00 PM
   Subject: ***SPAM*** [loopantennas] Re: Loops null direction

   Are you sure,Eduardo?
   Jose

   --- In loopantennas@yahoogroups.com, "EDUARDO" <adcas@...> wrote:
   >
   > Hello Ken
   >
   > The side is rejecting this "|", the other side "O" is what makes the best
capture. The band rejection is 80% in the "|".
   > Respectfully
   >
   > Eduardo L. Castaldelli
   > Mairipor�-SP-Brazil
   > Grid Locator: GG66qq
   > www.radiodx.qsl.br
   >
   >   ----- Original Message -----
   >   From: Ken
   >   To: loopantennas@yahoogroups.com
   >   Sent: Monday, November 09, 2009 2:46 PM
   >   Subject: ***SPAM*** [loopantennas] Loops null direction
   >
   >
   >   Hi All
   >
   >   I'm looking at a Wellbrook AL-330S. I know they can be mounted on a
   >   rotor and show some rejection. Do they reject when the loop is facing
   >   the noise or on the loops "edge"?
   >
   >   So is it the "O" or the "|" side that rejects?
   >
   >   Thanks
   >   Ken
   >
   >
   >
   >   ------------------------------------

   ------------------------------------

   If you've got links, post them in the Links section!
   http://groups.yahoo.com/group/loopantennas/links

   Post files here. If the file comes from a website, please put it in the Links
rather than uploading the file.
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   You can now view images at higher resolution in Photos. Upload JPG and GIF
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   And please trim all this when replying!Yahoo! Groups Links

[Non-text portions of this message have been removed]

#6880

From: loopantennas@yahoogroups.com
Date: Mon Nov 9, 2009 7:19 pm
Subject: New file uploaded to loopantennas

loopantennas@yahoogroups.com

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the loopantennas
group.

   File        : /Nulls loop.doc
   Uploaded by : adcasziza <adcas@...>
   Description : picture of diagram

You can access this file at the URL:
http://groups.yahoo.com/group/loopantennas/files/Nulls%20loop.doc

To learn more about file sharing for your group, please visit:
http://help.yahoo.com/l/us/yahoo/groups/original/general.htmlfiles

Regards,

adcasziza <adcas@...>

Reply | Messages in this Topic (122)

#6881

From: Jim Dunstan <jimdunstan@...>
Date: Mon Nov 9, 2009 7:22 pm
Subject: Re: Loops null direction

norlink88

At 04:46 PM 11/9/2009 +0000, you wrote:
>
>
>Hi All
>
>I'm looking at a Wellbrook AL-330S. I know they can be mounted on a
>rotor and show some rejection. Do they reject when the loop is facing
>the noise or on the loops "edge"?
>
>So is it the "O" or the "|" side that rejects?
>
>Thanks
>Ken

Hi,

The radiation/reception pattern of a large loop is maximum perpendicular to
the loop plane with nulls off the sides.  Small loops (which includes the
Al-330s) are opposite .. e.g. maximum off the sides of the loop and nulls
perpendicular to the plane of the loop.

Jim, VE3CI

#6882

From: "EDUARDO" <adcas@...>
Date: Mon Nov 9, 2009 7:24 pm
Subject: Re: Re: Loops null direction

adcasziza

See in the  down link

http://f1.grp.yahoofs.com/v1/sGb4SkLOKRZF7CyqQuNyNs98pzPujuQxGsqSsezNRJSj1UBQ3y9\
V2CgTqgIrLaADkiiDzj7aNKLmkaROhZwn2yb1-j__J7N1/Nulls%20loop.doc

Respectfully,

Eduardo L. Castaldelli
  Mairipor�-SP-Brazil
Grid Locator: GG66qq
www.radiodx.qsl.br



   ----- Original Message -----
   From: EDUARDO
   To: loopantennas@yahoogroups.com
   Sent: Monday, November 09, 2009 5:16 PM
   Subject: ***SPAM*** Re:[loopantennas] Re: Loops null direction


   See de picture!

   Respectfully,

   Eduardo L. Castaldelli
    Mairipor�-SP-Brazil
   Grid Locator: GG66qq
   www.radiodx.qsl.br





   ----- Original Message -----
     From: jaafes
     To: loopantennas@yahoogroups.com
     Sent: Monday, November 09, 2009 4:00 PM
     Subject: ***SPAM*** [loopantennas] Re: Loops null direction


     Are you sure,Eduardo?
     Jose


     --- In loopantennas@yahoogroups.com, "EDUARDO" <adcas@...> wrote:
     >
     > Hello Ken
     >
     > The side is rejecting this "|", the other side "O" is what makes the best
capture. The band rejection is 80% in the "|".
     > Respectfully
     >
     > Eduardo L. Castaldelli
     > Mairipor�-SP-Brazil
     > Grid Locator: GG66qq
     > www.radiodx.qsl.br
     >
     >   ----- Original Message -----
     >   From: Ken
     >   To: loopantennas@yahoogroups.com
     >   Sent: Monday, November 09, 2009 2:46 PM
     >   Subject: ***SPAM*** [loopantennas] Loops null direction
     >
     >
     >   Hi All
     >
     >   I'm looking at a Wellbrook AL-330S. I know they can be mounted on a
     >   rotor and show some rejection. Do they reject when the loop is facing
     >   the noise or on the loops "edge"?
     >
     >   So is it the "O" or the "|" side that rejects?
     >
     >   Thanks
     >   Ken
     >
     >
     >
     >   ------------------------------------




     ------------------------------------

     If you've got links, post them in the Links section!
     http://groups.yahoo.com/group/loopantennas/links

     Post files here. If the file comes from a website, please put it in the
Links rather than uploading the file.
     http://groups.yahoo.com/group/loopantennas/files

     You can now view images at higher resolution in Photos. Upload JPG and GIF
into Photos. Please convert BMP or TIF to JPG or GIF before uploading.
     http://ph.groups.yahoo.com/group/loopantennas/photos

     And please trim all this when replying!Yahoo! Groups Links




   [Non-text portions of this message have been removed]



   ------------------------------------

   If you've got links, post them in the Links section!
   http://groups.yahoo.com/group/loopantennas/links

   Post files here. If the file comes from a website, please put it in the Links
rather than uploading the file.
   http://groups.yahoo.com/group/loopantennas/files

   You can now view images at higher resolution in Photos. Upload JPG and GIF
into Photos. Please convert BMP or TIF to JPG or GIF before uploading.
   http://ph.groups.yahoo.com/group/loopantennas/photos

   And please trim all this when replying!Yahoo! Groups Links




[Non-text portions of this message have been removed]

#6883

From: Jim Dunstan <jimdunstan@...>
Date: Mon Nov 9, 2009 7:30 pm
Subject: Re: Loops null direction

norlink88

At 02:57 PM 11/9/2009 -0200, you wrote:
>
>
>Hello Ken
>
>The side is rejecting this "|", the other side "O" is what makes the best
>capture. The band rejection is 80% in the "|".
>Respectfully
>
>Eduardo L. Castaldelli
>Mairipor�-SP-Brazil
>Grid Locator: GG66qq
>www.radiodx.qsl.br

Eduardo,

What u say is correct for large loops ... eg 1/2 wavelength or
larger.  Small loops ... tuned or untuned are the opposite.   With a small
loop "0" gives maximum rejection/null ... while "I" gives maximum
reception.  Of course the null is sharp and maximum reception is broad.

We are either 100% correct or 100% incorrect hi hi ...

Jim, VE3CI

#6884

From: Paul V Birke PEng <nonlinear@...>
Date: Mon Nov 9, 2009 8:08 pm
Subject: Re: Loops null direction

pvbirke

reason is that small loops responds to intregal H*dl=N*i responds to current and
in fact we have a delta H across the loop on a line of Max H

hitting loop is Hmax and other side of loop is Hmin   and delta H = Hmax - Hmin

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

for larger loop we get the voltage relationship  e= N *2 *Pi*f* Phi=
N*2*Pi*f*B*A= 2*Pi*N*u0*ur*H* A

where ur=1.0 for ail
u0=4*Pi*10^(-7)

and A = loop area in m^2
and Phi in webers
Phi = B*A

best Paul


________________________________
From: Jim Dunstan <jimdunstan@...>
To: loopantennas@yahoogroups.com
Sent: Mon, November 9, 2009 2:30:07 PM
Subject: Re: [loopantennas] Loops null direction


At 02:57 PM 11/9/2009 -0200, you wrote:
>
>
>Hello Ken
>
>The side is rejecting this "|", the other side "O" is what makes the best
>capture. The band rejection is 80% in the "|".
>Respectfully
>
>Eduardo L. Castaldelli
>Mairiporã-SP- Brazil
>Grid Locator: GG66qq
>www.radiodx. qsl.br

Eduardo,

What u say is correct for large loops ... eg 1/2 wavelength or
larger.  Small loops ... tuned or untuned are the opposite.   With a small
loop "0" gives maximum rejection/null ... while "I" gives maximum
reception.  Of course the null is sharp and maximum reception is broad.

We are either 100% correct or 100% incorrect hi hi ...

Jim, VE3CI




[Non-text portions of this message have been removed]

#6885

From: aimo ruoho <aimounto@...>
Date: Mon Nov 9, 2009 10:07 pm
Subject: Re: Re: Loops null direction

aimounto

Thanks, but when Itry this given URL, I get "DOCUMENT NOT FOUND"

--- On Mon, 11/9/09, EDUARDO <adcas@...> wrote:

From: EDUARDO <adcas@...>
Subject: Re: [loopantennas] Re: Loops null direction
To: loopantennas@yahoogroups.com
Date: Monday, November 9, 2009, 8:24 PM

       See in the  down link

http://f1.grp. yahoofs.com/ v1/sGb4SkLOKRZF7 CyqQuNyNs98pzPuj uQxGsqSsezNRJSj1
UBQ3y9V2CgTqgIrL aADkiiDzj7aNKLmk aROhZwn2yb1- j__J7N1/Nulls% 20loop.doc

Respectfully,

Eduardo L. Castaldelli

  Mairiporã-SP- Brazil

Grid Locator: GG66qq

www.radiodx. qsl.br

----- Original Message -----

   From: EDUARDO

   To: loopantennas@ yahoogroups. com

   Sent: Monday, November 09, 2009 5:16 PM

   Subject: ***SPAM*** Re:[loopantennas] Re: Loops null direction

See de picture!

Respectfully,

Eduardo L. Castaldelli

    Mairiporã-SP- Brazil

   Grid Locator: GG66qq

   www.radiodx. qsl.br

----- Original Message -----

     From: jaafes

     To: loopantennas@ yahoogroups. com

     Sent: Monday, November 09, 2009 4:00 PM

     Subject: ***SPAM*** [loopantennas] Re: Loops null direction

Are you sure,Eduardo?

     Jose

--- In loopantennas@ yahoogroups. com, "EDUARDO" <adcas@...> wrote:

     >

     > Hello Ken

     >

     > The side is rejecting this "|", the other side "O" is what makes the best
capture. The band rejection is 80% in the "|".

     > Respectfully

     >

     > Eduardo L. Castaldelli

     > Mairiporã-SP- Brazil

     > Grid Locator: GG66qq

     > www.radiodx. qsl.br

     >

     >   ----- Original Message -----

     >   From: Ken

     >   To: loopantennas@ yahoogroups. com

     >   Sent: Monday, November 09, 2009 2:46 PM

     >   Subject: ***SPAM*** [loopantennas] Loops null direction

     >

     >

     >   Hi All

     >

     >   I'm looking at a Wellbrook AL-330S. I know they can be mounted on a

     >   rotor and show some rejection. Do they reject when the loop is facing

     >   the noise or on the loops "edge"?

     >

     >   So is it the "O" or the "|" side that rejects?

     >

     >   Thanks

     >   Ken

     >

     >

     >

     >   ------------ --------- --------- ------

------------ --------- --------- ------

If you've got links, post them in the Links section!

     http://groups. yahoo.com/ group/loopantenn as/links

Post files here. If the file comes from a website, please put it in the Links
rather than uploading the file.

     http://groups. yahoo.com/ group/loopantenn as/files

You can now view images at higher resolution in Photos. Upload JPG and GIF into
Photos. Please convert BMP or TIF to JPG or GIF before uploading.

     http://ph.groups. yahoo.com/ group/loopantenn as/photos

And please trim all this when replying!Yahoo! Groups Links

[Non-text portions of this message have been removed]

------------ --------- --------- ------

If you've got links, post them in the Links section!

   http://groups. yahoo.com/ group/loopantenn as/links

Post files here. If the file comes from a website, please put it in the Links
rather than uploading the file.

   http://groups. yahoo.com/ group/loopantenn as/files

You can now view images at higher resolution in Photos. Upload JPG and GIF into
Photos. Please convert BMP or TIF to JPG or GIF before uploading.

   http://ph.groups. yahoo.com/ group/loopantenn as/photos

And please trim all this when replying!Yahoo! Groups Links

[Non-text portions of this message have been removed]

[Non-text portions of this message have been removed]

#6886

From: "AlienRelics" <alienrelics@...>
Date: Mon Nov 9, 2009 10:16 pm
Subject: Re: Loops null direction

alienrelics

That link doesn't work for me, it looks like a link to a file in your Yahoo
mail? Or you linked to a location in Files, those only work for 30 minutes to
prevent file leaching.

I found it:
<http://groups.yahoo.com/group/loopantennas/files/Nulls%20loop.doc>

It is better if you don't use spaces in file names. You must replace every space
with %20.

I also strongly recommend against posting scanned/raster images inside a DOC
file. Just upload it as a JPG or GIF, it is easier to view and the file is a lot
smaller.

Steve Greenfield

--- In loopantennas@yahoogroups.com, "EDUARDO" <adcas@...> wrote:
>
> See in the  down link
>
>
http://f1.grp.yahoofs.com/v1/sGb4SkLOKRZF7CyqQuNyNs98pzPujuQxGsqSsezNRJSj1UBQ3y9\
V2CgTqgIrLaADkiiDzj7aNKLmkaROhZwn2yb1-j__J7N1/Nulls%20loop.doc
>
> Respectfully,
>
> Eduardo L. Castaldelli
>  Mairipor�-SP-Brazil
> Grid Locator: GG66qq
> www.radiodx.qsl.br
>
>

#6887

From: Michael in Suffolk <michaelrae65@...>
Date: Tue Nov 10, 2009 10:42 am
Subject: Sprial loop 48 x 48 inch

michaelrae65

Hi. I have just made a 48 x 48 inch sprial loop { looked at PICS could not see
very many}�and am having tuning capacitor - or wire�problems.
�I also have a 24 x 24 sprial loop with 11 turns�and that is giving no problems
at all. OK the set up here is I have about 7 variable metal VTC caps and have
tired them all in either paraible wire up or just one vain and earth side all
these either having 8 x 11 or 13 x 13 vane or a combo of 8 min�to 16 max�vane.
�I also have some old flat bakerlite types dylictric!�from the 1950 or before,
and only ONE of those�works great with�one wire to the main tuning vanes and the
other to the other side, full tuning with this useing single stranded pvc
covered wire, tuning�is from 470-1.800.�
�THe 48 x 48 inch sprial - Now when I put on any one of�the METAL caps the
tuning will not go down the even 1.610 all of them�stop at about 1.530 khz, Yes
I have put on one� turn, taken off a turn, total being either from 6-7-9-13�used
one side of a vane set and so on, made the wire spacing wider - made it closer
to no avail, could it be the 24 strand wire that is the problem, as on the 24 x
24 sprial loop it is single strand, ......help its driving me crazy. PICS of my
loops and VTC are on skywavemw not good at giving a link as not very much up
with PCs, but you just might find me I hope. Mike UK Bungay Suffolk.��




[Non-text portions of this message have been removed]

Reply | Messages in this Topic (1)

#6888

From: "gmcjetpilot" <gmcjetpilot@...>
Date: Tue Nov 10, 2009 6:06 pm
Subject: Re: Loops null direction

gmcjetpilot

The sides or the loop (the hole or "O") is the null

The edge "|" is the Aim

http://www.mindspring.com/~loop_antenna/edgewound_reception.gif

" The pickup pattern is shaped like a figure eight. The loop will allow signals
on opposite sides to be received, while off the sides of the loop the signal
will decrease or be null-ed out. The nulling feature will allow you to remove a
local station on a frequency and pick up another on the same frequency by
removing the local signal. A loop may have an amplifier or may not."

NOTE: The actual pattern is VERY COMPLEX, three dimensional and affected by its
surroundings and ground.

http://www.pa0sim.nl/circular%20polarization.htm
http://www.pa0sim.nl/loops%20in%20real%20life.htm

You can AIM at an offending STATION offending station or noise and detune the
loop for that Freq, to NULL that signal, using broad reception (of lower gain)
off the side, Or turn a loop null side to block signals. Some times 45 degrees
will do both block and gain.

You can use two or more loops (an array) and do all kinds of NULL and AIM to
hear a distant weak stations while rejecting noise and stronger local stations.

http://www.pa0sim.nl/dual%20loop%20system.htm

This is what makes loops so interesting and powerful, not to mention they are
WAY more compact than equivalent "Long Wire" antennas. Of course loops are best
at LF, MW and SW/HF. At the VHF freq and UHF things change. The wave length is
so short a 1/2 or full wave length whip or wire antenna is practical. Also
because VHF and UHF tends to penetrate the ionosphere (not skip off) you don't
get SKIP or sky waves, it becomes LINE OF SIGHT.

Keep in mind depending on the design of the loop the null can be deep or
shallow. The Wellbrook has off side reception, just not the same gain. I suspect
this is because it is an ACTIVE loop for one.

Also SOME signals come from the SKY, so no matter what way you have it pointed
the signal is coming down on the top of the loop or EDGE. Some people will tilt
their LOOP (usually big manually manipulated loops) on a gimbal. The TILT or
azimuth can block local signals and I assume get a SKY wave better, improve
gain, depending on the angle the sky wave is.

Keep in mind there are PASSIVE loops and ACTIVE loops (amplified).

NOTE: On a loop stick, a ferrite bar with wire winding, it is some what
opposite. The longitudinal axis of the ferrite bar is the AIM and the side,
(edge) of the coil winding is the NULL.

http://www.radio-electronics.com/info/antennas/ferrite_rod_antenna/ferrite_rod_a\
ntenna_operation.gif

--- In loopantennas@yahoogroups.com, "Ken" <faxcap@...> wrote:
>
> Hi All
>
> I'm looking at a Wellbrook AL-330S. I know they can be mounted on a
> rotor and show some rejection. Do they reject when the loop is facing
> the noise or on the loops "edge"?
>
> So is it the "O" or the "|" side that rejects?
>
> Thanks
> Ken
>

#6889

From: "brian russell" <brian-nsl@...>
Date: Tue Nov 10, 2009 7:10 pm
Subject: Re: Loops null direction

brian-nsl@...

Paul,
        Though way over my head I am impressed by your calculations.
How does a vertical diamond shaped loop compare with a square one ????
                                       72, Brian, G0NSL-QRP.


   ----- Original Message -----
   From: Paul V Birke PEng
   To: loopantennas@yahoogroups.com
   Sent: Monday, November 09, 2009 8:08 PM
   Subject: Re: [loopantennas] Loops null direction

[Non-text portions of this message have been removed]

#6890

From: Paul V Birke PEng <nonlinear@...>
Date: Tue Nov 10, 2009 9:29 pm
Subject: Re: Loops null direction

pvbirke

dear brian

the optimal shape for a loop is a rectangle with rounded corner

the German army used an oval shaped profile

it would be as if you had a circle and compressed at the top so the one ends up
with a fully rounded sides and flat at the top and bottom

so likely the above is better than a square for diamond

you need the rounded corners according to the theory

what I cannot remember now is whether the above applies to only small loops  yes
I think it is small loops

what is also interesting there is an olde swedish patent on having two loops
offset by something like 10 or 20 degrees for accurate direction finding and
extra gain I think with the extra loop

it is a US patent from like 1933

anyways hope that helps

other likely know much more than above
best wishes
Paul





________________________________
From: brian russell <brian-nsl@...>
To: loopantennas@yahoogroups.com
Sent: Tue, November 10, 2009 2:10:44 PM
Subject: Re: [loopantennas] Loops null direction


Paul,
Though way over my head I am impressed by your calculations.
How does a vertical diamond shaped loop compare with a square one ????
72, Brian, G0NSL-QRP.

----- Original Message -----
From: Paul V Birke PEng
To: loopantennas@ yahoogroups. com
Sent: Monday, November 09, 2009 8:08 PM
Subject: Re: [loopantennas] Loops null direction

[Non-text portions of this message have been removed]




[Non-text portions of this message have been removed]