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Re: Loop reflector

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  • longjohn119
    I think that would actually be considered a ground plane rather than a reflector. It may be of some assistance for a loop mounted high off the ground or on
    Message 1 of 23 , Jan 2, 2011
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      I think that would actually be considered a ground plane rather than a reflector. It may be of some assistance for a loop mounted high off the ground or on 'real' ground that is lossy due to factors you can't control ( location specific and rare). If you have the loop up high, I'd try setting it up temporarily on real ground and see if it seems to help the performance and/or noise. If it does then making an artificial ground plane for your usual mount position up high should benefit. If you don't see a difference I wouldn't waste my time.

      JR

      --- In loopantennas@yahoogroups.com, "Joey" <joeyh1951@...> wrote:
      >
      > what has anyone experienced using a reflector under the loop they operate on? Is there a real increase in gain?
      >
    • Andy
      ... Just curious ... why do you say that? In your eye, what is the difference between a ground plane and a reflector? Me, I d call it a reflector if it is a
      Message 2 of 23 , Jan 3, 2011
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        > I think that would actually be considered a ground plane rather than a reflector.

        Just curious ... why do you say that? In your eye, what is the
        difference between a ground plane and a reflector?

        Me, I'd call it a reflector if it is a wire loop under the radiating
        loop. If it is a solid sheet of metal, or a wire mesh that extends
        well beyond the circumference of the loop, then I'd call it a ground
        plane.

        Many people who do NVIS find a marked improvement when they lay a
        reflector wire or two underneath their dipole, either on or a few
        inches above the ground. It might not help everywhere, but enough
        people have said that it helps, that I think there must be something
        to it. At least one person put a knife switch in the middle of his
        reflector wire, so he could see just how much improvement it makes.

        Your results may vary depending on frequency, on dimensions (size and
        spacing), on distance from ground, and on your particular soil
        conditions. The latter might not model very accurately in EZNEC.

        Andy
      • Steve Ellington
        Joey: I hope you are talking about a horizontal loop. Everyone seems to think you are but you might be talking about a little magnetic loop or something. Who
        Message 3 of 23 , Jan 3, 2011
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          Joey: I hope you are talking about a horizontal loop. Everyone seems to think you are but you might be talking about a little magnetic loop or something. Who knows.

          I had a 160 meter, full wave, loop up 60 feet and I put a reflector under it. The reflector was about 6 feet off the ground. Basically I had a cubical quad aimed straight up. I tried making the reflector 5% longer than the driven element.
          I could tell no difference on 160 meters but really....The only way to measure gain would be to fly above the antenna in a helicopter and use a very sensitive field strength meter.
          For a number of reasons, the reflector would not function on harmonics but especially since the loop no longer acted as an NVIS antenna.
          Bottom line: The reflector was a waste of time.

          Steve
          N4LQ
          ----- Original Message -----
          From: Joey
          To: loopantennas@yahoogroups.com
          Sent: Thursday, December 30, 2010 12:47 PM
          Subject: [loopantennas] Loop reflector



          what has anyone experienced using a reflector under the loop they operate on? Is there a real increase in gain?





          [Non-text portions of this message have been removed]
        • longjohn119
          If it s horizontal then it s omnidirectional so it definitely wouldn t qualify as a reflector which implies a directional antenna. Well maybe directional
          Message 4 of 23 , Jan 3, 2011
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            If it's horizontal then it's omnidirectional so it definitely wouldn't qualify as a reflector which implies a directional antenna. Well maybe directional straight up but I'm not sure what good that would do a guy

            JR

            --- In loopantennas@yahoogroups.com, "Steve Ellington" <n4lq@...> wrote:
            >
            > Joey: I hope you are talking about a horizontal loop. Everyone seems to think you are but you might be talking about a little magnetic loop or something. Who knows.
            >
            > I had a 160 meter, full wave, loop up 60 feet and I put a reflector under it. The reflector was about 6 feet off the ground. Basically I had a cubical quad aimed straight up. I tried making the reflector 5% longer than the driven element.
            > I could tell no difference on 160 meters but really....The only way to measure gain would be to fly above the antenna in a helicopter and use a very sensitive field strength meter.
            > For a number of reasons, the reflector would not function on harmonics but especially since the loop no longer acted as an NVIS antenna.
            > Bottom line: The reflector was a waste of time.
            >
            > Steve
            > N4LQ
            > ----- Original Message -----
            > From: Joey
            > To: loopantennas@yahoogroups.com
            > Sent: Thursday, December 30, 2010 12:47 PM
            > Subject: [loopantennas] Loop reflector
            >
            >
            >
            > what has anyone experienced using a reflector under the loop they operate on? Is there a real increase in gain?
            >
            >
            >
            >
            >
            > [Non-text portions of this message have been removed]
            >
          • Dale Parfitt
            A horizontal 1 wavelength loop, if up sufficently high, has a radiation pattern almost identical to a half wave dipole- that is a figure 8 pattern. Dale W4OP
            Message 5 of 23 , Jan 3, 2011
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              A horizontal 1 wavelength loop, if up sufficently high, has a radiation
              pattern almost identical to a half wave dipole- that is a figure 8 pattern.

              Dale W4OP

              If it's horizontal then it's omnidirectional so it definitely wouldn't
              qualify as a reflector which implies a directional antenna. Well maybe
              directional straight up but I'm not sure what good that would do a guy

              JR
            • Steve Ellington
              Yep....Straight up is exactly what I meant. A reflector under a horizontal loop does the same thing as the earth but with slightly less loss. The ultimate
              Message 6 of 23 , Jan 3, 2011
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                Yep....Straight up is exactly what I meant. A reflector under a horizontal loop does the same thing as the earth but with slightly less loss. The ultimate reflector would be solid copper under the loop.

                I remember reading an article in a British publication concerning a cubicle quad antenna. Seems that a storm had bent the mast and the quad became horizontal. The author reported that many signals were stronger and surmised that many signals, even on 20 meters, arrive at very high angles.

                Steve
                N4LQ
                ----- Original Message -----
                From: longjohn119
                To: loopantennas@yahoogroups.com
                Sent: Tuesday, January 04, 2011 12:05 AM
                Subject: [loopantennas] Re: Loop reflector



                If it's horizontal then it's omnidirectional so it definitely wouldn't qualify as a reflector which implies a directional antenna. Well maybe directional straight up but I'm not sure what good that would do a guy

                JR

                --- In loopantennas@yahoogroups.com, "Steve Ellington" <n4lq@...> wrote:
                >
                > Joey: I hope you are talking about a horizontal loop. Everyone seems to think you are but you might be talking about a little magnetic loop or something. Who knows.
                >
                > I had a 160 meter, full wave, loop up 60 feet and I put a reflector under it. The reflector was about 6 feet off the ground. Basically I had a cubical quad aimed straight up. I tried making the reflector 5% longer than the driven element.
                > I could tell no difference on 160 meters but really....The only way to measure gain would be to fly above the antenna in a helicopter and use a very sensitive field strength meter.
                > For a number of reasons, the reflector would not function on harmonics but especially since the loop no longer acted as an NVIS antenna.
                > Bottom line: The reflector was a waste of time.
                >
                > Steve
                > N4LQ
                > ----- Original Message -----
                > From: Joey
                > To: loopantennas@yahoogroups.com
                > Sent: Thursday, December 30, 2010 12:47 PM
                > Subject: [loopantennas] Loop reflector
                >
                >
                >
                > what has anyone experienced using a reflector under the loop they operate on? Is there a real increase in gain?
                >
                >
                >
                >
                >
                > [Non-text portions of this message have been removed]
                >





                [Non-text portions of this message have been removed]
              • Andy
                Non-directional in 2 dimensions does not mean non-directional in 3 dimensions. A cubical quad is a directional antenna no matter how you orient it, as long as
                Message 7 of 23 , Jan 4, 2011
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                  Non-directional in 2 dimensions does not mean non-directional in 3
                  dimensions. A cubical quad is a directional antenna no matter how you
                  orient it, as long as you are looking at it in 3D.

                  Horizontal full-wave loops are quite useful, for NVIS and high angle
                  communications, which many hams use without realizing it. Yes,
                  cloud-burners are actually important, on the lower HF frequencies, for
                  regional coverage. Generally not so much for DX. (Which is not to
                  say that horizontal loops can't also work for DX, on higher freqs.)

                  Andy
                • Andy
                  ... Where did you hear that? A full wavelength loop, in free space, has a pattern that looks like a dumbbell: two major lobes in opposite directions
                  Message 8 of 23 , Jan 5, 2011
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                    > A horizontal 1 wavelength loop, if up sufficently high, has a radiation
                    > pattern almost identical to a half wave dipole- that is a figure 8 pattern.

                    Where did you hear that?

                    A full wavelength loop, in free space, has a pattern that looks like a
                    dumbbell: two major lobes in opposite directions (perpendicular to the
                    loop), and a null going a full 360 degrees around it in the plane of
                    the loop.

                    A half wave dipole has a pattern like a donut, which is almost exactly
                    the opposite.

                    So I'm trying to figure out what orientations of the loop and of the
                    dipole you are envisioning.

                    Most half wave wire dipoles are horizontal, and tend to have maximum
                    signal broadside to the wire, and nulls off the ends (except for
                    interaction with the earth or ionospheric reflections). A full wave
                    loop at any height is essentially nondirectional with respect to its
                    axis. Its primary radiation is straight up and straight down, so it
                    makes a good antenna for high angle signals; though if you mount it a
                    half wave above earth, it may get a null going straight up due to
                    cancellation with its reflection.

                    Andy
                  • Dale Parfitt
                    I didn t hear it, I modeled it with EZNEC. Think of a 1 wavelength horizontal loop as two half wave dipoles spaced 1/4 wavelength apart- it is obvious this is
                    Message 9 of 23 , Jan 5, 2011
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                      I didn't hear it, I modeled it with EZNEC. Think of a 1 wavelength
                      horizontal loop as two half wave dipoles spaced 1/4 wavelength apart- it is
                      obvious this is not omni and will have classic construction and destruction
                      azimuth pattern.

                      Dale W4OP


                      > A horizontal 1 wavelength loop, if up sufficently high, has a radiation
                      > pattern almost identical to a half wave dipole- that is a figure 8
                      > pattern.

                      Where did you hear that?

                      A full wavelength loop, in free space, has a pattern that looks like a
                      dumbbell: two major lobes in opposite directions (perpendicular to the
                      loop), and a null going a full 360 degrees around it in the plane of
                      the loop.

                      A half wave dipole has a pattern like a donut, which is almost exactly
                      the opposite.

                      So I'm trying to figure out what orientations of the loop and of the
                      dipole you are envisioning.

                      Most half wave wire dipoles are horizontal, and tend to have maximum
                      signal broadside to the wire, and nulls off the ends (except for
                      interaction with the earth or ionospheric reflections). A full wave
                      loop at any height is essentially nondirectional with respect to its
                      axis. Its primary radiation is straight up and straight down, so it
                      makes a good antenna for high angle signals; though if you mount it a
                      half wave above earth, it may get a null going straight up due to
                      cancellation with its reflection.

                      Andy






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                    • Andy
                      ... OK ... but now think of it as four shortened (quarter wave) dipoles in a square. Now it s not so obvious that it might have classic dipole radiation
                      Message 10 of 23 , Jan 5, 2011
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                        > ... Think of a 1 wavelength
                        > horizontal loop as two half wave dipoles spaced 1/4 wavelength apart- it is
                        > obvious this is not omni  and will have classic construction and destruction
                        > azimuth pattern.

                        OK ... but now think of it as four shortened (quarter wave) dipoles in a square.

                        Now it's not so obvious that it might have classic dipole radiation
                        characteristics.

                        Thinking that a loop is like two dipoles in parallel, is a real stretch.

                        And in fact a good 1 wavelength loop radiates nothing like a dipole!

                        Bend a circular loop into a square or triangle, and it's not quite so
                        omni anymore; but it's still close enough for government work.

                        Andy
                      • Dale Parfitt
                        You cannot think of it as 4 1/4 wave dipoles as there are only 2 current loops. Model the antenna with any of the popular software ad we can end this
                        Message 11 of 23 , Jan 5, 2011
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                          You cannot think of it as 4 1/4 wave dipoles as there are only 2 current loops.
                          Model the antenna with any of the popular software ad we can end this disagreement.
                          The models converge very nicely and do not disobey any of the miniNEC limitations.
                          Dale W4OP

                          ----- Original Message -----
                          From: Andy
                          To: loopantennas@yahoogroups.com
                          Sent: Wednesday, January 05, 2011 6:23 PM
                          Subject: Re: [loopantennas] Re: Loop reflector



                          > ... Think of a 1 wavelength
                          > horizontal loop as two half wave dipoles spaced 1/4 wavelength apart- it is
                          > obvious this is not omni and will have classic construction and destruction
                          > azimuth pattern.

                          OK ... but now think of it as four shortened (quarter wave) dipoles in a square.

                          Now it's not so obvious that it might have classic dipole radiation
                          characteristics.

                          Thinking that a loop is like two dipoles in parallel, is a real stretch.

                          And in fact a good 1 wavelength loop radiates nothing like a dipole!

                          Bend a circular loop into a square or triangle, and it's not quite so
                          omni anymore; but it's still close enough for government work.

                          Andy





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                        • Steve Ellington
                          Andy; I m glad you spoke up. Here is a link to an Eznec model of an 80m horizontal loop. I ve never heard anyone claim a loop had the same pattern as a dipole
                          Message 12 of 23 , Jan 5, 2011
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                            Andy;
                            I'm glad you spoke up.
                            Here is a link to an Eznec model of an 80m horizontal loop. I've never heard anyone claim a loop had the same pattern as a dipole until now.
                            At typical heights, this loop has a circular pattern and vertical radiation is straight up. At greater, 1/2 wavelength, heights the pattern will show a bit of a bulge opposite the feedpoint and a lower angle. Of course the pattern changes for the harmonics but never the same as a dipole. It's a great multiband antenna and very common.
                            73
                            http://www.iw5edi.com/ham-radio/files/k0ze-loop.pdf


                            Steve
                            N4LQ
                            ----- Original Message -----
                            From: Andy
                            To: loopantennas@yahoogroups.com
                            Sent: Wednesday, January 05, 2011 6:23 PM
                            Subject: Re: [loopantennas] Re: Loop reflector



                            > ... Think of a 1 wavelength
                            > horizontal loop as two half wave dipoles spaced 1/4 wavelength apart- it is
                            > obvious this is not omni and will have classic construction and destruction
                            > azimuth pattern.

                            OK ... but now think of it as four shortened (quarter wave) dipoles in a square.

                            Now it's not so obvious that it might have classic dipole radiation
                            characteristics.

                            Thinking that a loop is like two dipoles in parallel, is a real stretch.

                            And in fact a good 1 wavelength loop radiates nothing like a dipole!

                            Bend a circular loop into a square or triangle, and it's not quite so
                            omni anymore; but it's still close enough for government work.

                            Andy




                            [Non-text portions of this message have been removed]
                          • Dale Parfitt
                            Hi Steve, That loop is virtually on the ground at 1/8 wavelength- any horizontal antenna that low is going to be an omni. Also look at the elevation slice
                            Message 13 of 23 , Jan 5, 2011
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                              Hi Steve,
                              That loop is virtually on the ground at 1/8 wavelength- any horizontal antenna that low is going to be an omni. Also look at the elevation slice angle -90 degrees.

                              My statement said "of sufficient height".
                              Do you want me to send you the EZNEC wirelist of a full wave loop in free space vs a dipole in free space- the patterns are almost identical.

                              Dale W4OP



                              Andy;
                              I'm glad you spoke up.
                              Here is a link to an Eznec model of an 80m horizontal loop. I've never heard anyone claim a loop had the same pattern as a dipole until now.
                              At typical heights, this loop has a circular pattern and vertical radiation is straight up. At greater, 1/2 wavelength, heights the pattern will show a bit of a bulge opposite the feedpoint and a lower angle. Of course the pattern changes for the harmonics but never the same as a dipole. It's a great multiband antenna and very common.
                              73
                              http://www.iw5edi.com/ham-radio/files/k0ze-loop.pdf

                              Steve
                              N4LQ
                              ----- Original Message -----


                              Steve,

                              This loop is virtually on the ground- 35'. Also look at the elevation slice for the azimuth plot- 90 degrees.

                              Model the antenna at 1 wavelength above ground at look at the low angle pattern.

                              .




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                            • longjohn119
                              All adding a reflector underneath will do is act like lowering the antenna closer to the ground I bet .... Could you simulate something like that in EZNEC? It
                              Message 14 of 23 , Jan 12, 2011
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                                All adding a reflector underneath will do is act like lowering the antenna closer to the ground I bet .... Could you simulate something like that in EZNEC?

                                It would also alter the take off angle I would think

                                JR

                                --- In loopantennas@yahoogroups.com, "Dale Parfitt" <parinc1@...> wrote:
                                >
                                > Hi Steve,
                                > That loop is virtually on the ground at 1/8 wavelength- any horizontal antenna that low is going to be an omni. Also look at the elevation slice angle -90 degrees.
                                >
                                > My statement said "of sufficient height".
                                > Do you want me to send you the EZNEC wirelist of a full wave loop in free space vs a dipole in free space- the patterns are almost identical.
                                >
                                > Dale W4OP
                                >
                                >
                              • M HOLDEN
                                Think about a 2 ele quad. They beam sideways. Now flip it through 90deg........Simples !................Mike G4HOL ... From: longjohn119
                                Message 15 of 23 , Jan 12, 2011
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                                  Think about a 2 ele quad. They beam sideways. Now flip it through 90deg........Simples !................Mike G4HOL

                                  --- On Wed, 12/1/11, longjohn119 <some_oil_with_your_teaparty@...> wrote:

                                  From: longjohn119 <some_oil_with_your_teaparty@...>
                                  Subject: [loopantennas] Re: Loop reflector
                                  To: loopantennas@yahoogroups.com
                                  Date: Wednesday, 12 January, 2011, 17:42







                                   









                                  All adding a reflector underneath will do is act like lowering the antenna closer to the ground I bet .... Could you simulate something like that in EZNEC?



                                  It would also alter the take off angle I would think



                                  JR



                                  --- In loopantennas@yahoogroups.com, "Dale Parfitt" <parinc1@...> wrote:

                                  >

                                  > Hi Steve,

                                  > That loop is virtually on the ground at 1/8 wavelength- any horizontal antenna that low is going to be an omni. Also look at the elevation slice angle -90 degrees.

                                  >

                                  > My statement said "of sufficient height".

                                  > Do you want me to send you the EZNEC wirelist of a full wave loop in free space vs a dipole in free space- the patterns are almost identical.

                                  >

                                  > Dale W4OP

                                  >

                                  >






















                                  [Non-text portions of this message have been removed]
                                • Andy
                                  ... The idea behind adding a reflector wire under a dipole used for NVIS, is the same as a reflector loop under a horizontal loop. They both are meant to
                                  Message 16 of 23 , Jan 12, 2011
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                                    > All adding a reflector underneath will do is act like lowering the antenna closer to the ground I bet ....

                                    The idea behind adding a reflector wire under a dipole used for NVIS,
                                    is the same as a reflector loop under a horizontal loop. They both
                                    are meant to improve the reflection (and the high angle signal), by
                                    removing most of the loss of the earth from the system.

                                    If you live in an area with a very good (conductive) ground, it might
                                    not help much; but if you have more typical or poor ground conditions,
                                    where much of your signal penetrating the earth gets absorbed instead
                                    of reflecting, coherently, then a reflector wire or loop may indeed
                                    help.

                                    > Could you simulate something like that in EZNEC?

                                    Sure you can simulate it, but you may need to question how accurate it
                                    is, given the difficulty modeling earth near an antenna.

                                    Actual observations with reflector wires under a dipole, have shown
                                    that it can make a significant improvement, but others reported no
                                    apparent difference. (I'm paraphrasing from personal experiences I've
                                    read elsewhere.)

                                    Andy
                                  • longjohn119
                                    I will not work like a quabic quad for a couple of reasons 1. Main element only 1/8 wavelength from ground causing distortion of pattern 2. Reflector is
                                    Message 17 of 23 , Jan 17, 2011
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                                      I will not work like a quabic quad for a couple of reasons

                                      1. Main element only 1/8 wavelength from ground causing distortion of pattern

                                      2. Reflector is therefore much less than 1/8 from main element causing distortion of pattern

                                      3. Reflector is considerably less than 1/8 wavelength from ground causing even more distortion of the pattern and it's probably not going to work like a reflector at all even in the slightest being more or less cancelled out by the effects of ground

                                      You can't ignore the effects of ground on both elements, nor the fact the spacing between elements themselves and elements and ground is way off and to make a model work correctly you have to take into account the ground effects and the highly 'squashed' spacing between elements




                                      --- In loopantennas@yahoogroups.com, M HOLDEN <mholden909@...> wrote:
                                      >
                                      > Think about a 2 ele quad. They beam sideways. Now flip it through 90deg........Simples !................Mike G4HOL
                                      >
                                      > --- On Wed, 12/1/11, longjohn119 <some_oil_with_your_teaparty@...> wrote:
                                      >
                                      > From: longjohn119 <some_oil_with_your_teaparty@...>
                                      > Subject: [loopantennas] Re: Loop reflector
                                      > To: loopantennas@yahoogroups.com
                                      > Date: Wednesday, 12 January, 2011, 17:42
                                      >
                                      >
                                      >
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                                      >  
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                                      > All adding a reflector underneath will do is act like lowering the antenna closer to the ground I bet .... Could you simulate something like that in EZNEC?
                                      >
                                      >
                                      >
                                      > It would also alter the take off angle I would think
                                      >
                                      >
                                      >
                                      > JR
                                      >
                                      >
                                      >
                                      > --- In loopantennas@yahoogroups.com, "Dale Parfitt" <parinc1@> wrote:
                                      >
                                      > >
                                      >
                                      > > Hi Steve,
                                      >
                                      > > That loop is virtually on the ground at 1/8 wavelength- any horizontal antenna that low is going to be an omni. Also look at the elevation slice angle -90 degrees.
                                      >
                                      > >
                                      >
                                      > > My statement said "of sufficient height".
                                      >
                                      > > Do you want me to send you the EZNEC wirelist of a full wave loop in free space vs a dipole in free space- the patterns are almost identical.
                                      >
                                      > >
                                      >
                                      > > Dale W4OP
                                      >
                                      > >
                                      >
                                      > >
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                                      > [Non-text portions of this message have been removed]
                                      >
                                    • Andy
                                      ... You are right that its pattern won t be exactly the same as a free-space quagi tipped on its side. But yagi antennas (as a general class of antennas with a
                                      Message 18 of 23 , Jan 18, 2011
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                                        > I(t) will not work like a quabic quad for a couple of reasons
                                        >
                                        > 1. Main element only 1/8 wavelength from ground causing distortion
                                        > of pattern
                                        >
                                        > 2. Reflector is therefore much less than 1/8 from main element
                                        > causing distortion of pattern
                                        >
                                        > 3. Reflector is considerably less than 1/8 wavelength from ground
                                        > causing even more distortion of the pattern and it's probably not going
                                        > to work like a reflector at all even in the slightest being more or less
                                        > cancelled out by the effects of ground

                                        You are right that its pattern won't be exactly the same as a
                                        free-space quagi tipped on its side.

                                        But yagi antennas (as a general class of antennas with a radiator and
                                        one or more passive parasitic elements) can be made with all kinds of
                                        inter-element spacings. There are the NIST spacings, or you can
                                        optimize for bandwidth, or you can optimize for maximum gain/length,
                                        etc. There is no one yagi design. And there are perfectly good
                                        compact yagis with far less than 1/8 wavelength spacing ... and they
                                        do work. Yes, the pattern will be different than a longer yagi, and
                                        the bandwidth may not be the same, but they too are quite acceptable
                                        antennas.

                                        There indeed is some interaction between the reflector loop and the
                                        earth beneath it, just as there is between every antenna and earth,
                                        and that is somewhat of an unknown (due in part to the variability of
                                        soil types). It's not right to say that one cancels out the other.

                                        The fact that people have been making "cloud burners" for decades,
                                        some adding low reflector wires under their antennas, and many finding
                                        that it helps, can't be discarded either. I think it is definitely
                                        wrong to say that it "won't work like a reflector at all even in the
                                        slightest".

                                        Regards,
                                        Andy
                                      • Dale Parfitt
                                        K6STI (author of AO, a very nice MiniNEC engine based modeling tool) had an article in QST or QEX some years back illustrating how even HF Yagis can be tuned
                                        Message 19 of 23 , Jan 18, 2011
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                                          K6STI (author of AO, a very nice MiniNEC engine based modeling tool) had an article in QST or QEX some years back illustrating how even HF Yagis can be tuned for best VSWR near the ground by aiming them straight up. Obviously the reflector needs to be off the ground somewhat. The results appear very much as though the antenna is in "free space". This assumes that the antenna has a good F/B ratio.
                                          You can model this for yourself. I have used the technique for HF Moxons with perfect results. Tune them aimed into space and put them on the tower and nothing changes.

                                          73,
                                          Dale W4OP

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