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RE: [loopantennas] Re: 3/4" Soft copper?

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  • W1EOF
    Hi Dave, I m new to this group so I need some help with this. I understand why on transmitting loops resistance is such a factor because the current is so
    Message 1 of 7 , Jul 30, 2005
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      Hi Dave,

      I'm new to this group so I need some help with this. I understand why on
      transmitting loops resistance is such a factor because the current is so
      high. High current + high resistance = high losses.

      I don't understand why it matters much at all on a receive loop. It would
      seem to be a insignificant factor compared to all the others such as capture
      area, etc.

      73,

      Mark W1EOF
      -----Original Message-----
      From: dldorrance [mailto:dldorrance@...]
      Sent: Saturday, July 30, 2005 3:48 PM
      To: loopantennas@yahoogroups.com
      Subject: [loopantennas] Re: 3/4" Soft copper?


      Aluminum is probably not a good idea for a small loop. The aluminum
      has higher resistive losses than copper. And with a small loop this
      loss is in series with the radiation resistance which is on the order
      of 0.1 ohm. So you are talking about a significant voltage drop,
      which reduces both receive and transmit signals.

      Dave WA6YSO

      --- In loopantennas@yahoogroups.com, "Henry Kolesnik" <kolesnik@s...>
      wrote:
      > It might cost a little more but is easier to use and you don't need
      any ells. Perhaps a cheaper way is to get some 75 ohm Al CATV line
      and use it or a piece of >1/2" Andrew Heliax.
      >
      > 73
      > Hank WD5JFR
      >
      > ----- Original Message -----
      > From: mdgolfbum
      > To: loopantennas@yahoogroups.com
      > Sent: Friday, July 29, 2005 6:01 PM
      > Subject: [loopantennas] 3/4" Soft copper?
      >
      >
      > I've seen several loops with 3/4" hard copper, typically octagonal.
      > I've also seen 5/8" soft copper done in a circle.
      >
      > My hardware store has 3/4" soft copper coiled. Is there some reason
      > why others haven't tried this in a circle?
      >
      > I'm considering a 40/30/20M loop for QRP base station.
      >
      > tnx
      > jtm ab3cv
      >
      >
      >
      >
      >
      >
      >
      > If you've got links, post them in the Links section!
      > http://groups.yahoo.com/group/loopantennas/links
      >
      > For uploading images, I prefer the Files section since Photos only
      allows everyone (except the uploader and moderators) to see a max of
      300x400.
      > http://groups.yahoo.com/group/loopantennas/files
      >
      > Put them in the appropriate folder, or create one.
      >
      >
      >
      > SPONSORED LINKS Loop antenna
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      If you've got links, post them in the Links section!
      http://groups.yahoo.com/group/loopantennas/links

      For uploading images, I prefer the Files section since Photos only allows
      everyone (except the uploader and moderators) to see a max of 300x400.
      http://groups.yahoo.com/group/loopantennas/files

      Put them in the appropriate folder, or create one.



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      [Non-text portions of this message have been removed]
    • dldorrance
      Well I think this question will be a matter of some controversy on this group. Here is my personal situation. My lot is very small and has power lines on 2
      Message 2 of 7 , Aug 1, 2005
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        Well I think this question will be a matter of some controversy on
        this group.

        Here is my personal situation. My lot is very small and has power
        lines on 2 sides. The nearest to my roof (where my loop is installed)
        I am told is 10 kV. The other provides lower voltage with feeds to
        each house. So as you can imagine, I have a lot of noise on receive.
        (Noise mitigation being the reason I use loops in the first place).

        Here is my observation experimenting with different loop
        configurations. My small transmitting loop for 20 meters uses a high
        grade split stator capacitor (stator plates soldered). I observed
        that the noise level increased dramatically after swapping this
        capacitor with an old ARC-5 capacitor with a wiper containing
        non-removable discoloration (higher resistance) . The noise level
        decreased after re-insertion of the split stator capacitor. "If you
        can't hear 'em you can't work 'em".

        I grant you this is a special case. But I think it emphasizes the
        point that if you want a stronger receive antenna it pays to build in
        maximum efficiency, because on the margin (very weak signals) a
        difference is noticeable.

        Dave WA6YSO





        --- In loopantennas@yahoogroups.com, "W1EOF" <w1eof@h...> wrote:
        > Hi Dave,
        >
        > I'm new to this group so I need some help with this. I understand why on
        > transmitting loops resistance is such a factor because the current is so
        > high. High current + high resistance = high losses.
        >
        > I don't understand why it matters much at all on a receive loop. It
        would
        > seem to be a insignificant factor compared to all the others such as
        capture
        > area, etc.
        >
        > 73,
        >
        > Mark W1EOF
        > -----Original Message-----
        > From: dldorrance [mailto:dldorrance@h...]
        > Sent: Saturday, July 30, 2005 3:48 PM
        > To: loopantennas@yahoogroups.com
        > Subject: [loopantennas] Re: 3/4" Soft copper?
        >
        >
        > Aluminum is probably not a good idea for a small loop. The aluminum
        > has higher resistive losses than copper. And with a small loop this
        > loss is in series with the radiation resistance which is on the order
        > of 0.1 ohm. So you are talking about a significant voltage drop,
        > which reduces both receive and transmit signals.
        >
        > Dave WA6YSO
        >
        > --- In loopantennas@yahoogroups.com, "Henry Kolesnik" <kolesnik@s...>
        > wrote:
        > > It might cost a little more but is easier to use and you don't need
        > any ells. Perhaps a cheaper way is to get some 75 ohm Al CATV line
        > and use it or a piece of >1/2" Andrew Heliax.
        > >
        > > 73
        > > Hank WD5JFR
        > >
        > > ----- Original Message -----
        > > From: mdgolfbum
        > > To: loopantennas@yahoogroups.com
        > > Sent: Friday, July 29, 2005 6:01 PM
        > > Subject: [loopantennas] 3/4" Soft copper?
        > >
        > >
        > > I've seen several loops with 3/4" hard copper, typically
        octagonal.
        > > I've also seen 5/8" soft copper done in a circle.
        > >
        > > My hardware store has 3/4" soft copper coiled. Is there some
        reason
        > > why others haven't tried this in a circle?
        > >
        > > I'm considering a 40/30/20M loop for QRP base station.
        > >
        > > tnx
        > > jtm ab3cv
        > >
        > >
        > >
        > >
        > >
        > >
        > >
        > > If you've got links, post them in the Links section!
        > > http://groups.yahoo.com/group/loopantennas/links
        > >
        > > For uploading images, I prefer the Files section since Photos only
        > allows everyone (except the uploader and moderators) to see a max of
        > 300x400.
        > > http://groups.yahoo.com/group/loopantennas/files
        > >
        > > Put them in the appropriate folder, or create one.
        > >
        > >
        > >
        > > SPONSORED LINKS Loop antenna
        > >
        > >
        > >
        >
        --------------------------------------------------------------------------
        > ----
        > > YAHOO! GROUPS LINKS
        > >
        > > a.. Visit your group "loopantennas" on the web.
        > >
        > > b.. To unsubscribe from this group, send an email to:
        > > loopantennas-unsubscribe@yahoogroups.com
        > >
        > > c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of
        > Service.
        > >
        > >
        > >
        >
        --------------------------------------------------------------------------
        > ----
        > >
        > >
        > >
        > > [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
        >
        > For uploading images, I prefer the Files section since Photos only
        allows
        > everyone (except the uploader and moderators) to see a max of 300x400.
        > http://groups.yahoo.com/group/loopantennas/files
        >
        > Put them in the appropriate folder, or create one.
        >
        >
        >
        >
        ----------------------------------------------------------------------------
        > --
        > YAHOO! GROUPS LINKS
        >
        > a.. Visit your group "loopantennas" on the web.
        >
        > b.. To unsubscribe from this group, send an email to:
        > loopantennas-unsubscribe@yahoogroups.com
        >
        > c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of
        > Service.
        >
        >
        >
        ----------------------------------------------------------------------------
        > --
        >
        >
        >
        > [Non-text portions of this message have been removed]
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