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Re: Looking for 3 band receiving loop...

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  • gplynas
    Hi Steve, Many years ago I designed a broadband loop for monitoring radio-navigation beacons which had to cover the frequency range of 195 kHz to 480 kHz. Our
    Message 1 of 10 , Apr 1 7:19 AM
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      Hi Steve,
      Many years ago I designed a broadband loop for monitoring
      radio-navigation beacons which had to cover the frequency range of 195
      kHz to 480 kHz. Our previous loops were tuned single-frequency. I
      designed this one by looking at the loop as the "inductor" in a Pi
      network, with a transformation ratio from (radiation resistance + loss
      resistance) to the input impedance of the amplifier, and with a
      break-point above the highest frequency. I fed this into an FET
      amplifier with high input impedance. A resistor of about 10k
      furnished a return to ground at the amplifier input and stabilized the
      gain. The whole circuit was then feed with +15 VDC through the coax
      from the receiver.

      This worked well, with a response that was reasonably flat over more
      than 2 octaves. I think the same concept could be used from 160M to
      40M. By design, I was able to reject the broadcast band signals which
      could overload a broadband design.
      Regards,
      Paul Lynas
      WA5LFY

      --- In loopantennas@yahoogroups.com, "n6vl" <n6vl@...> wrote:
      >
      > Hi,
      >
      > I am looking for a receiving loop I can use on the 160, 80, and 40
      > meters ham bands. It can be either an indoor loop in my ham shack. Or
      > it can be a larger outdoor one. I hope to find one I can use on all the
      > lower HF ham bands. Many designs are for single band. Perhaps there is
      > a design on posted on this group I simply haven't noticed.
      >
      > Thanks in advance!
      >
      > Steve N6VL
      >
    • David Atkins
      Paul, I, for one would be very interested to see your loop design ... From: loopantennas@yahoogroups.com [mailto:loopantennas@yahoogroups.com]On Behalf Of
      Message 2 of 10 , Apr 1 7:35 AM
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        Paul,

        I, for one would be very interested to see your loop design


        -----Original Message-----
        From: loopantennas@yahoogroups.com
        [mailto:loopantennas@yahoogroups.com]On Behalf Of gplynas
        Sent: 01 April 2007 15:19
        To: loopantennas@yahoogroups.com
        Subject: [loopantennas] Re: Looking for 3 band receiving loop...


        Hi Steve,
        Many years ago I designed a broadband loop for monitoring
        radio-navigation beacons which had to cover the frequency range of 195
        kHz to 480 kHz. Our previous loops were tuned single-frequency. I
        designed this one by looking at the loop as the "inductor" in a Pi
        network, with a transformation ratio from (radiation resistance + loss
        resistance) to the input impedance of the amplifier, and with a
        break-point above the highest frequency. I fed this into an FET
        amplifier with high input impedance. A resistor of about 10k
        furnished a return to ground at the amplifier input and stabilized the
        gain. The whole circuit was then feed with +15 VDC through the coax
        from the receiver.

        This worked well, with a response that was reasonably flat over more
        than 2 octaves. I think the same concept could be used from 160M to
        40M. By design, I was able to reject the broadcast band signals which
        could overload a broadband design.
        Regards,
        Paul Lynas
        WA5LFY
      • c.e.boyd
        Hi Paul: Do you recall the values for the coil and caps you used for this LW antenna? Also to modify this antenna for the low freq ham bands, (not 60) what
        Message 3 of 10 , Apr 1 9:24 AM
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          Hi Paul: Do you recall the values for the coil and caps you used for this LW
          antenna? Also to modify this antenna for the low freq ham bands, (not 60)
          what would be the necessary values? Thanks: theboyd
          ----- Original Message -----
          From: "gplynas" <gplynas@...>
          To: <loopantennas@yahoogroups.com>
          Sent: Sunday, April 01, 2007 8:19 AM
          Subject: [loopantennas] Re: Looking for 3 band receiving loop...


          > Hi Steve,
          > Many years ago I designed a broadband loop for monitoring
          > radio-navigation beacons which had to cover the frequency range of 195
          > kHz to 480 kHz. Our previous loops were tuned single-frequency. I
          > designed this one by looking at the loop as the "inductor" in a Pi
          > network, with a transformation ratio from (radiation resistance + loss
          > resistance) to the input impedance of the amplifier, and with a
          > break-point above the highest frequency. I fed this into an FET
          > amplifier with high input impedance. A resistor of about 10k
          > furnished a return to ground at the amplifier input and stabilized the
          > gain. The whole circuit was then feed with +15 VDC through the coax
          > from the receiver.
          >
          > This worked well, with a response that was reasonably flat over more
          > than 2 octaves. I think the same concept could be used from 160M to
          > 40M. By design, I was able to reject the broadcast band signals which
          > could overload a broadband design.
          > Regards,
          > Paul Lynas
          > WA5LFY
        • Paul Birke
          Dear Paul that seems like a very clever idea to make the loop part of some input filter system is there a history to this, I have never seen this mentioned
          Message 4 of 10 , Apr 1 9:33 AM
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            Dear Paul

            that seems like a very clever idea to make the loop part of some input filter system

            is there a history to this, I have never seen this mentioned before then again what do I know

            anyways it stikes me one could has many variations of the basic Loop looked as and inductance in front end R L C filter circuits or even active circuits IMHO

            best
            Paul Birke PEng
            Guelph


            ----- Original Message ----
            From: gplynas <gplynas@...>
            To: loopantennas@yahoogroups.com
            Sent: Sunday, April 1, 2007 10:19:27 AM
            Subject: [loopantennas] Re: Looking for 3 band receiving loop...

            Hi Steve,
            Many years ago I designed a broadband loop for monitoring
            radio-navigation beacons which had to cover the frequency range of 195
            kHz to 480 kHz. Our previous loops were tuned single-frequency. I
            designed this one by looking at the loop as the "inductor" in a Pi
            network, with a transformation ratio from (radiation resistance + loss
            resistance) to the input impedance of the amplifier, and with a
            break-point above the highest frequency. I fed this into an FET
            amplifier with high input impedance. A resistor of about 10k
            furnished a return to ground at the amplifier input and stabilized the
            gain. The whole circuit was then feed with +15 VDC through the coax
            from the receiver.

            This worked well, with a response that was reasonably flat over more
            than 2 octaves. I think the same concept could be used from 160M to
            40M. By design, I was able to reject the broadcast band signals which
            could overload a broadband design.
            Regards,
            Paul Lynas
            WA5LFY

            --- In loopantennas@ yahoogroups. com, "n6vl" <n6vl@...> wrote:
            >
            > Hi,
            >
            > I am looking for a receiving loop I can use on the 160, 80, and 40
            > meters ham bands. It can be either an indoor loop in my ham shack. Or
            > it can be a larger outdoor one. I hope to find one I can use on all the
            > lower HF ham bands. Many designs are for single band. Perhaps there is
            > a design on posted on this group I simply haven't noticed.
            >
            > Thanks in advance!
            >
            > Steve N6VL
            >




            [Non-text portions of this message have been removed]
          • gplynas
            Hi Paul, My design of this loop dates from the late 70s to the early 80s so it has been a few years. I came up with the idea of placing the loop within the
            Message 5 of 10 , Apr 1 1:10 PM
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              Hi Paul, My design of this loop dates from the late '70s to the early
              '80s so it has been a few years. I came up with the idea of placing
              the loop within the filter after looking at the flatness of response
              and impedance of a three element Butterworth type filter. The
              radiation resistance plus loop losses can be converted to an
              equivalent input impedance for design purposes, with the filter
              designed around the inductance of the loop. I looked for my notes on
              the design, but what remains is from memory. I'll see if I can put
              together a paper design that we can try.

              Best Regards,
              Paul Lynas
              WA5LFY

              --- In loopantennas@yahoogroups.com, Paul Birke <nonlinear@...> wrote:
              >
              > Dear Paul
              >
              > that seems like a very clever idea to make the loop part of some
              input filter system
              >
              > is there a history to this, I have never seen this mentioned before
              then again what do I know
              >
              > anyways it stikes me one could has many variations of the basic Loop
              looked as and inductance in front end R L C filter circuits or even
              active circuits IMHO
              >
              > best
              > Paul Birke PEng
              > Guelph
              >
              >
              > ----- Original Message ----
              > From: gplynas <gplynas@...>
              > To: loopantennas@yahoogroups.com
              > Sent: Sunday, April 1, 2007 10:19:27 AM
              > Subject: [loopantennas] Re: Looking for 3 band receiving loop...
              >
              > Hi Steve,
              > Many years ago I designed a broadband loop for monitoring
              > radio-navigation beacons which had to cover the frequency range of 195
              > kHz to 480 kHz. Our previous loops were tuned single-frequency. I
              > designed this one by looking at the loop as the "inductor" in a Pi
              > network, with a transformation ratio from (radiation resistance + loss
              > resistance) to the input impedance of the amplifier, and with a
              > break-point above the highest frequency. I fed this into an FET
              > amplifier with high input impedance. A resistor of about 10k
              > furnished a return to ground at the amplifier input and stabilized the
              > gain. The whole circuit was then feed with +15 VDC through the coax
              > from the receiver.
              >
              > This worked well, with a response that was reasonably flat over more
              > than 2 octaves. I think the same concept could be used from 160M to
              > 40M. By design, I was able to reject the broadcast band signals which
              > could overload a broadband design.
              > Regards,
              > Paul Lynas
              > WA5LFY
              >
              > --- In loopantennas@ yahoogroups. com, "n6vl" <n6vl@> wrote:
              > >
              > > Hi,
              > >
              > > I am looking for a receiving loop I can use on the 160, 80, and 40
              > > meters ham bands. It can be either an indoor loop in my ham shack. Or
              > > it can be a larger outdoor one. I hope to find one I can use on
              all the
              > > lower HF ham bands. Many designs are for single band. Perhaps
              there is
              > > a design on posted on this group I simply haven't noticed.
              > >
              > > Thanks in advance!
              > >
              > > Steve N6VL
              > >
              >
              >
              >
              >
              > [Non-text portions of this message have been removed]
              >
            • Paul Birke
              Dear Paul ok great -- again such a clever idea the embedding of the antenna loop (or loops if one wanted to get fancy) in a number of filter
              Message 6 of 10 , Apr 1 1:55 PM
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                Dear Paul

                ok great -- again such a clever idea the embedding of the antenna loop (or loops if one wanted to get fancy) in a number of filter configurations--like you say Butterworth being one of a few

                >>the mind spins on this one<<

                could you widen the bandwidth by effectively lowering the Q of the inherent tuned circuit: i,e.;
                once you have caps there you are talking about resonance

                but I am thinking of something with a low and high pass together effectively a a bandpass circuit with the loop in the middle so it was not a sharply turned as a tuned loop if you get my drift here

                could one made a filter with the loop or loops having an extended bandwidth but which sharp sides and of course enjoy the better signal to noise ratio and yet preserve the directional characteristics which should remain purely a function of the loop etc

                just musing I guess

                best
                Paul


                ----- Original Message ----
                From: gplynas <gplynas@...>
                To: loopantennas@yahoogroups.com
                Sent: Sunday, April 1, 2007 4:10:39 PM
                Subject: [loopantennas] Re: Looking for 3 band receiving loop...

                Hi Paul, My design of this loop dates from the late '70s to the early
                '80s so it has been a few years. I came up with the idea of placing
                the loop within the filter after looking at the flatness of response
                and impedance of a three element Butterworth type filter. The
                radiation resistance plus loop losses can be converted to an
                equivalent input impedance for design purposes, with the filter
                designed around the inductance of the loop. I looked for my notes on
                the design, but what remains is from memory. I'll see if I can put
                together a paper design that we can try.

                Best Regards,
                Paul Lynas
                WA5LFY

                --- In loopantennas@ yahoogroups. com, Paul Birke <nonlinear@. ..> wrote:
                >
                > Dear Paul
                >
                > that seems like a very clever idea to make the loop part of some
                input filter system
                >
                > is there a history to this, I have never seen this mentioned before
                then again what do I know
                >
                > anyways it stikes me one could has many variations of the basic Loop
                looked as and inductance in front end R L C filter circuits or even
                active circuits IMHO
                >
                > best
                > Paul Birke PEng
                > Guelph
                >
                >
                > ----- Original Message ----
                > From: gplynas <gplynas@... >
                > To: loopantennas@ yahoogroups. com
                > Sent: Sunday, April 1, 2007 10:19:27 AM
                > Subject: [loopantennas] Re: Looking for 3 band receiving loop...
                >
                > Hi Steve,
                > Many years ago I designed a broadband loop for monitoring
                > radio-navigation beacons which had to cover the frequency range of 195
                > kHz to 480 kHz. Our previous loops were tuned single-frequency. I
                > designed this one by looking at the loop as the "inductor" in a Pi
                > network, with a transformation ratio from (radiation resistance + loss
                > resistance) to the input impedance of the amplifier, and with a
                > break-point above the highest frequency. I fed this into an FET
                > amplifier with high input impedance. A resistor of about 10k
                > furnished a return to ground at the amplifier input and stabilized the
                > gain. The whole circuit was then feed with +15 VDC through the coax
                > from the receiver.
                >
                > This worked well, with a response that was reasonably flat over more
                > than 2 octaves. I think the same concept could be used from 160M to
                > 40M. By design, I was able to reject the broadcast band signals which
                > could overload a broadband design.
                > Regards,
                > Paul Lynas
                > WA5LFY
                >
                > --- In loopantennas@ yahoogroups. com, "n6vl" <n6vl@> wrote:
                > >
                > > Hi,
                > >
                > > I am looking for a receiving loop I can use on the 160, 80, and 40
                > > meters ham bands. It can be either an indoor loop in my ham shack. Or
                > > it can be a larger outdoor one. I hope to find one I can use on
                all the
                > > lower HF ham bands. Many designs are for single band. Perhaps
                there is
                > > a design on posted on this group I simply haven't noticed.
                > >
                > > Thanks in advance!
                > >
                > > Steve N6VL
                > >
                >
                >
                >
                >
                > [Non-text portions of this message have been removed]
                >




                [Non-text portions of this message have been removed]
              • n6vl
                Hi Paul, In my case I don t need the preamp. I use an ICOM 756PROII which has a preamp. In fact on the lower HF bands, I throw in 6 or 12 db of attentuation to
                Message 7 of 10 , Apr 1 7:24 PM
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                  Hi Paul,

                  In my case I don't need the preamp. I use an ICOM 756PROII which has
                  a preamp. In fact on the lower HF bands, I throw in 6 or 12 db of
                  attentuation to aid reception in noisy conditions.

                  I am trying to visualize your loop. It has a little less range than
                  what I desire. Multiplying by a factor of 10, your loop would span
                  from 1.95 to 4.8 MHz. Am I asking too great of a range for a single
                  loop. It is common to get a loop work 160 and 80 meters or 80 and 40
                  meters.

                  I have looked at loop design at http://www.hard-core-
                  dx.com/nordicdx/antenna/loop/coaxloop.html. It uses two shielded coax
                  loops in the same plane with a common feed. The loop at this URL is
                  for 80 and 160 meters. I need 80 and 40 meters at this time. 160
                  meter can come later as I don't have a decent transmitting antenna
                  right now.

                  I don't often see receiving loops for 40 meters and very rarely for
                  any higher HF bands. I have been using a diagonally polarized delta
                  loop 225 feet in circumfernce for transmitting on 40 and 80 meters. I
                  started using a 44 foot dipole centered fed with balanced line on 30
                  meters and above as it gives a nice broadside pattern up through 10
                  meters. I notice this dipole has a better S/N ratio 40 and 80 meters.
                  I adjust the balanced tuner for maximun signal and don't worry about
                  SWR. It definitely gives a few db of noise reduction on reception. I
                  am baffled that the dipole hears better since loops are often
                  credited as good receiving antennas in terms of S/N ratio. The large
                  delta loop is still used to transmit on 40 and 80 meters.

                  I hope to find a loop to give me even better S/N ratios than the 44
                  foot dipole. I am open to a desktop unit in the shack or something in
                  my backyard. I have the right rig for separate receive antennas and
                  would like to try a receiving loop since summer is coming and the
                  static levels will increase.

                  Paul, could you comment in a little more detail about your design and
                  how I might approach this for the lower HF bands.

                  73,

                  Steve N6VL
                • Jim Morrison
                  ... Hi Steve, W4RNL has several articles on the Loop antenna, but this one seems like a good place to start for your question:
                  Message 8 of 10 , Apr 9 5:10 AM
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                    --- "n6vl" <n6vl@...> wrote:
                    > I am looking for a receiving loop I can use on the 160, 80, and 40
                    > meters ham bands.

                    Hi Steve,

                    W4RNL has several articles on the Loop antenna, but this one
                    seems like a good place to start for your question:
                    http://www.cebik.com/fdim/atl1.html

                    Poke around here for some additional Loop info:
                    http://cebik.com/radio.html

                    73, Jim N9GTM
                  • n6vl
                    Jim, Thanks for the info. I already a semi-horizontal loop now. My main is interest is in small receiving loops with improve S/N ratio and not for
                    Message 9 of 10 , Apr 14 5:18 PM
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                      Jim,

                      Thanks for the info. I already a semi-horizontal loop now. My main is
                      interest is in small receiving loops with improve S/N ratio and not for
                      transmitting. Many of the loops in this group are for reception only.

                      73,

                      Steve N6VL
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