## Shielded multi turn loop

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• Hi all, I like to construct a multi turn shielded loop with RG6 coax. I have already a cross section frame with sides of 1.5 meters or 6 meters per turn. I
Message 1 of 5 , Feb 1, 2008
Hi all,

I like to construct a multi turn shielded loop with RG6 coax. I have
already a cross section frame with sides of 1.5 meters or 6 meters per
turn. I have a coil of 100 meter RG6 standing aside to use.

My frequency range will be from 150 to 500 khz. Can I make a direct
coupling with the transmission line or do I have to make a single turn
coupler link. I like to use varicaps to remotely tune the loop.

How can I proceede?

Greetings,
Ron
ON3RON, DXA64
• ... No ideas? Ron
Message 2 of 5 , Feb 8, 2008
--- In loopantennas@yahoogroups.com, "dxnature" <amazingalgo@...> wrote:
>
> Hi all,
>
> I like to construct a multi turn shielded loop with RG6 coax. I have
> already a cross section frame with sides of 1.5 meters or 6 meters per
> turn. I have a coil of 100 meter RG6 standing aside to use.
>
> My frequency range will be from 150 to 500 khz. Can I make a direct
> coupling with the transmission line or do I have to make a single turn
> coupler link. I like to use varicaps to remotely tune the loop.
>
> How can I proceede?
>
> Greetings,
> Ron
> ON3RON, DXA64
>

No ideas?

Ron
• Unless someone has already worked out a formula, it may be a bit of cut and try. There is at least one Javascript on a website in the Links section (also
Message 3 of 5 , Feb 8, 2008
Unless someone has already worked out a formula, it may be a bit of
cut and try. There is at least one Javascript on a website in the
Links section (also mentioned recently, search for loop calculator in
the archives) that calculates with a fixed spacing. You'll also have
to take into account capacitance of the cable, there's where the
cut-and-try comes in.

I went and looked it up, here's Bruce Carter's javascript loop
calculator. Uses turn spacing rather than loop width. Enter values,
guessing at minimum capacitance, then calculate cable capacitance and
use that to get a more accurate guess at minimum capacitance, repeat
'til the values don't change.
http://www.mindspring.com/~loop_antenna/umr_emc_calc.htm

I would think a single loop coupling would be better than a direct
loop.

Steve Greenfield

--- In loopantennas@yahoogroups.com, "dxnature" <amazingalgo@...> wrote:
>
> Hi all,
>
> I like to construct a multi turn shielded loop with RG6 coax. I have
> already a cross section frame with sides of 1.5 meters or 6 meters per
> turn. I have a coil of 100 meter RG6 standing aside to use.
>
> My frequency range will be from 150 to 500 khz. Can I make a direct
> coupling with the transmission line or do I have to make a single turn
> coupler link. I like to use varicaps to remotely tune the loop.
>
> How can I proceede?
>
> Greetings,
> Ron
> ON3RON, DXA64
>
• ... have ... meters per ... direct ... turn ... Ron, What you are envisioning sounds challenging and could present some problems to fuction effectively in a
Message 4 of 5 , Feb 8, 2008
--- In loopantennas@yahoogroups.com, "dxnature" <amazingalgo@...>
wrote:
>
> --- In loopantennas@yahoogroups.com, "dxnature" <amazingalgo@>
wrote:
> >
> > Hi all,
> >
> > I like to construct a multi turn shielded loop with RG6 coax. I
have
> > already a cross section frame with sides of 1.5 meters or 6
meters per
> > turn. I have a coil of 100 meter RG6 standing aside to use.
> >
> > My frequency range will be from 150 to 500 khz. Can I make a
direct
> > coupling with the transmission line or do I have to make a single
turn
> > coupler link. I like to use varicaps to remotely tune the loop.
> >
> > How can I proceede?
> >
> > Greetings,
> > Ron
> > ON3RON, DXA64
> >
>
> No ideas?
>
> Ron
>
Ron,
What you are envisioning sounds challenging and could present some
problems to fuction effectively in a remote application. I have
entertained the thought of using remotely tuned amp such as the
Ramsey signal magnet with a large remote air core. Unless you are in
a truely remote location, it would be more of a noise magnet though.
Shielding the loop using coax would involve breaking the shielding at
the top of each turn. The coax that feeds the loop also supplies the
tuning voltage. The loop can be 100's of ft away. Without knowing
your skill level, employing this or something similar (like the Degen
DE31?) could be easier to realize. If anything, maybe this will
stimulate more discussion...

Regards,
John
• Hi Steve, I made a conventional loop with 15 turns of wire on a 1.5 by 1.5 meter frame and 1 link coupling. It came almost on the resonated frequency I had
Message 5 of 5 , Feb 18, 2008
Hi Steve,

I made a conventional loop with 15 turns of wire on a 1.5 by 1.5
meter frame and 1 link coupling. It came almost on the resonated
frequency I had calculated. It tuned from 700 to 200 khz. Sorry to say
there is bit less noise and the signals are a bit stronger but not as
I expected it to be. Ok it is a step in the right direction but I'm
not content. There is still to mutch noise!!!

What I want to do right now is to replace the link coupling with a
coax loop as pick-up and connect this to the feed line. What do you
think? Will this give me a bit less noise?

Greetings,
Ron
>
> Unless someone has already worked out a formula, it may be a bit of
> cut and try. There is at least one Javascript on a website in the
> Links section (also mentioned recently, search for loop calculator in
> the archives) that calculates with a fixed spacing. You'll also have
> to take into account capacitance of the cable, there's where the
> cut-and-try comes in.
>
> I went and looked it up, here's Bruce Carter's javascript loop
> calculator. Uses turn spacing rather than loop width. Enter values,
> guessing at minimum capacitance, then calculate cable capacitance and
> use that to get a more accurate guess at minimum capacitance, repeat
> 'til the values don't change.
> http://www.mindspring.com/~loop_antenna/umr_emc_calc.htm
>
> I would think a single loop coupling would be better than a direct
> connection. Less affect on loop capacitance, less loading of the tuned
> loop.
>
> Steve Greenfield
>
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