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Re: Hex Beam - Effective height

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  • wd4elg_base
    Steve, this is awesome. help me with a dumb quesiton - would the 10 meter performance at 20 feet not resemble the 20 meter at 40 feet? i.e., scaling...double
    Message 1 of 20 , May 1, 2007
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      Steve, this is awesome.

      help me with a dumb quesiton - would the 10 meter performance at 20 feet
      not resemble the 20 meter at 40 feet? i.e., scaling...double the
      wavelength and halve the height for the same performance? I thought it
      worked this way with dipoles because of the height above ground.

      Mark, WD4ELG


      --- In hex-beam@yahoogroups.com, "Steve" <steve@...> wrote:
      >
      > John,
      >
      > A year or so ago I ran EZNEC simulations on 6 different antennas at
      > various heights above ground. At the low(ish) take-off angle of 10
      > degrees all antennas showed the same sort of signal increase with
      > increasing height. Here's some numbers referenced to 20ft
      >
      > 20m
      > 20ft:0dB / 25ft:+1.8dB / 30ft:+3.7dB / 35ft:+5.7dB / 40ft:+7.1dB
      >
      > 17m
      > 20ft:0dB / 25ft:+2.5dB / 30ft:+4.7dB / 35ft:+5.7dB / 40ft:+5.9dB
      >
      > 15m
      > 20ft:0dB / 25ft:+4.3dB / 30ft:+5.6dB / 35ft:+5.9dB / 40ft:+6.5dB
      >
      > 12m
      > 20ft:0dB / 25ft:+1.8dB / 30ft:+2.2dB / 35ft:+3.0dB / 40ft:+4.3dB
      >
      > 10m
      > 20ft:0dB / 25ft:+0.9dB / 30ft:+1.6dB / 35ft:+2.9dB / 40ft:+3.7dB
      >
    • Steve
      Mark, You re absolutely right - the performance vs height scales with Frequency. So, as you say, performance on 10m at 20ft would be very similar to the
      Message 2 of 20 , May 1, 2007
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        Mark,

        You're absolutely right - the performance vs height scales with
        Frequency. So, as you say, performance on 10m at 20ft would be very
        similar to the performance on 20m at 40ft. [There are some very minor
        differences caused by the wire diameter being fixed - it therefore
        becomes relatively thicker on 10m compared with 20m]

        Thscaling is NOT evident in my numbers because the performance on each
        band has been referenced to the 20ft performance ON THAT BAND. I
        presented the numbers this way to illustrate the performance
        enhancements that could be achieved on each band by various height
        increases.

        A dipole follows exactly the same trend, so the dBd figure for the
        HexBeam is pretty well independant of height.

        The "optimum height" question crops up fairly regularly on this Group,
        so this evening I added a page on the topic to my website:

        http://www.karinya.net/g3txq/hexbeam/height/

        Hopefully it might clarify a few issues.

        73,
        Steve G3TXQ
      • t_ashland
        Steve, Thanks for the great info. Very interesting reading! Also thanks to the other Hex Elmers, Leo, Holger, et. al. for making this such a great forum! 73,
        Message 3 of 20 , May 2, 2007
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          Steve,
          Thanks for the great info. Very interesting reading! Also thanks to
          the other Hex Elmers, Leo, Holger, et. al. for making this such a
          great forum!
          73,
          Terry, W0ZS


          --- In hex-beam@yahoogroups.com, "Steve" <steve@...> wrote:
          >
          > Mark,
          >
          > You're absolutely right - the performance vs height scales with
          > Frequency. So, as you say, performance on 10m at 20ft would be very
          > similar to the performance on 20m at 40ft. [There are some very
          minor
          > differences caused by the wire diameter being fixed - it therefore
          > becomes relatively thicker on 10m compared with 20m]
          >
          > Thscaling is NOT evident in my numbers because the performance on
          each
          > band has been referenced to the 20ft performance ON THAT BAND. I
          > presented the numbers this way to illustrate the performance
          > enhancements that could be achieved on each band by various height
          > increases.
          >
          > A dipole follows exactly the same trend, so the dBd figure for the
          > HexBeam is pretty well independant of height.
          >
          > The "optimum height" question crops up fairly regularly on this
          Group,
          > so this evening I added a page on the topic to my website:
          >
          > http://www.karinya.net/g3txq/hexbeam/height/
          >
          > Hopefully it might clarify a few issues.
          >
          > 73,
          > Steve G3TXQ
          >
        • wd4elg_base
          DOH! I see now, the numbers you provide are hex beam gain relative to dipole on that band at that height. So much for late-night reading on my part. Thanks,
          Message 4 of 20 , May 2, 2007
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            DOH! I see now, the numbers you provide are hex beam gain relative to
            dipole on that band at that height.

            So much for late-night reading on my part. Thanks, Steve.

            Mark, WD4ELG



            PS Anybody worked BS7H with a HexBeam yet?
          • wd4elg_base
            Ignore my last post, as I STILL did not get it until just now. All references are RELATIVE to 20 feet in height for the antenna on that band. He who
            Message 5 of 20 , May 2, 2007
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              Ignore my last post, as I STILL did not "get it" until just now. All
              references are RELATIVE to 20 feet in height for the antenna on that
              band.



              "He who laughs last...usually did not get the joke."



              Mark , WD4ELG
            • bur52@aol.com
              NO.. But I did work China, Tiawan..and Japan a few weeks back. But latelay the bands are a little up side down. Only hearing Europe and S. America on 20
              Message 6 of 20 , May 2, 2007
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                NO..

                But I did work China, Tiawan..and Japan a few weeks back. But latelay the
                bands are a little up side down.
                Only hearing Europe and S. America on 20 meters.

                Hex's rule ! :)
                JohnB
                k3jvb



                ************************************** See what's free at http://www.aol.com


                [Non-text portions of this message have been removed]
              • Steve
                Folks, For those who may be interested I just added an extra table to my new website page: http://www.karinya.net/g3txq/hexbeam/height/ The table shows the
                Message 7 of 20 , May 3, 2007
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                  Folks,

                  For those who may be interested I just added an extra table to my new
                  website page:

                  http://www.karinya.net/g3txq/hexbeam/height/

                  The table shows the relationship bewteen "Angle of Arrival" and
                  Distance for typical F2 Layer single-hop propagation paths. It should
                  help you decide what is your "optimum height"!

                  73,
                  Steve G3TXQ
                • wd4elg_base
                  Steve, Very cool. I looked in the antenna handbook and saw those graphs you are referring to. Not sure of the book has answers to this question: on longer
                  Message 8 of 20 , May 3, 2007
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                    Steve, Very cool. I looked in the antenna handbook and saw those
                    graphs you are referring to. Not sure of the book has answers to this
                    question: on longer distance communications (over 5000 km) it's
                    obviously muti-hop. Are there any stats for angle-of-arrival for
                    multi-hop? Or is it easier just to assume that the lowest angle is
                    best, therefore get it as high as possible without impacting the 30
                    degree angle adversely...which means 40-45 feet (ref to your graph,
                    Steve). I was initially disappointed when I saw your graph of the 5
                    degree angle performance for the hex as I was comparing it to a real
                    world dipole, but then remembered that for a dipole at half wavelength
                    it has a lobe at 30 degrees and has something like NEGATIVE 5 dbi at the
                    angle of 5 degrees. So at 5 degrees, the hex at 32 feet is 5 dbd
                    because the hex is 0dbi. At 15 degrees, the dipole is 3.5dbi, and the
                    hex is about 5.5 dbi, so at 30 degrees the hex is 2dbd at 15 degrees.
                    At 30 degrees, the halfwave dipole is at its peak at 6.73 dbi and the
                    hex is 8dbi, so the hex is 1.7dbd. So I ask myself this question: what
                    does the hex at 32 feet on 20 meters get me that the 20 meter half-wave
                    dipole at 32 feet does not, in terms of GAIN? Will I be able to hear
                    VR2XMT on the hex? I can't hear him on the dipole. In a situation
                    where the dipole and the hex are both optimum for signal reception
                    (dipole broadside to signal, hex pointed to signal), we would get:
                    Dipole Hex 30 deg 6.73dbi 8.0dbi 15 deg
                    3.5dbi 5.5dbi 5 deg -5.0dbi 0dbi
                    * 30 degrees - 1.7db better performance on the hex
                    * 15 degrees - 2 db better performance on the hex
                    * 5 degrees - 5 db better performance on the hex
                    Now, in a situation where the dipole performance is minimized and the
                    hex is optimum (endfire for dipole, hex pointed at the signal),
                    Dipole Hex 30 deg -2.0dbi 8.0dbi
                    15 deg -10.25dbi 5.5dbi 5 deg -18.96dbi
                    0dbi
                    * 30 degrees = 10db better performance on the hex

                    * 15 degrees = 15.75 db better performance on the hex
                    * 5 degrees = 18.96 db better performance on the hex
                    (Am I doing this correcectly?) So what does the hex get me over my
                    dipole at the same height, in terms of receiving the signal?
                    * If the signal arrives broadside to the dipole, the hext will beat
                    the dipole at the lower angles by a bit on reception.
                    * If the signal arrives "end-on" for the dipole, the hex will blow
                    the dipole away, especially at the lowest angles.
                    This is in pure gain numbers on reception. What ELSE does the hex
                    get me that the dipole does not?
                    Mark, WD4ELG

                    --- In hex-beam@yahoogroups.com, "Steve" <steve@...> wrote:
                    >
                    > Folks,
                    >
                    > For those who may be interested I just added an extra table to my new
                    > website page:
                    >
                    > http://www.karinya.net/g3txq/hexbeam/height/
                    >
                    > The table shows the relationship bewteen "Angle of Arrival" and
                    > Distance for typical F2 Layer single-hop propagation paths. It should
                    > help you decide what is your "optimum height"!
                    >
                    > 73,
                    > Steve G3TXQ
                    >



                    [Non-text portions of this message have been removed]
                  • Michael Doherty
                    ... What ELSE does the hex ... I found the hexbeam quieter than my comparison antenna, a horizontal loop. I suppose the front and side rejection helped with
                    Message 9 of 20 , May 3, 2007
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                      On 5/3/07, wd4elg_base <mlunday@...> wrote:
                      >
                      What ELSE does the hex
                      > get me that the dipole does not?

                      I found the hexbeam quieter than my comparison antenna, a horizontal
                      loop. I suppose the front and side rejection helped with that.
                    • Steve
                      Mark, Some interesting questions; I ll try to provide some simple answers:) Comparing a dipole in its optimum direction (broadside) with a Hex at the same
                      Message 10 of 20 , May 3, 2007
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                        Mark,

                        Some interesting questions; I'll try to provide some simple answers:)

                        Comparing a dipole in its optimum direction (broadside) with a Hex at
                        the same height, I get the following average Hex advantages:

                        5 degrees elevation: 3.6dBd
                        15 degrees elevation: 3.5dBd
                        30 degrees elevation: 3.2dBd

                        [These dBd figures are averaged for a range of heights from 10ft to
                        60ft.]

                        At elevations above about 45 degrees the Hex and the dipole lose
                        directivity until overhead they are both omnidirectional. So you
                        would expect the Hex's advantage to be most at the lower elevations.

                        Is 3.6dB worthwhile? Well, if a signal is on the limit of
                        intelligibilty it can make ALL the difference; but if the Signal /
                        Noise is already high you probably wouldn't notice it!

                        Don't forget though, that on Rx the Hex is also giving you the
                        benefit of its F/B. So two signals (in front and behind you) might be
                        equal strength on the dipole but 16dB different on the Hex.

                        And finally, there will be some locations that a Hex will fit that a
                        dipole wouldn't - remember, its half the turning radius!

                        73,
                        Steve G3TXQ
                      • wd4elg_base
                        John, My 20m hex is at 32 feet here in central NC, surrounded by trees and hills to the S and SW and NW. Had good results in April with my 100 watts until
                        Message 11 of 20 , May 3, 2007
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                          John,

                          My 20m hex is at 32 feet here in central NC, surrounded by trees and
                          hills to the S and SW and NW. Had good results in April with my 100
                          watts until this past weekend's CME and high solar wind:

                          CW: UN7, 9H1, SV9, ST, GJ, ZB, HC, UA0, R1(Franz Josef), 6V, 4L, TA, ZS

                          SSB: ZP8, OH, GD, ST, SV9, TA, 5B, UA0, T7

                          RTTY (35 W): VP5, UA, S5, 9A, ER, IS0, PZ, SV, OM

                          PSK (35W): ZL

                          HUGE CW CW PILEUP, GOT HIM ON FIRST CALL: KH8/AI4VU

                          HUGE PILEUP, GOT HIM ON SECOND CALL: N8S

                          (John, the SteppIR guys get to brag by posting on the DX cluster when
                          they do well. So we HEX owners should get to brag once in awhile too!)

                          [:D]



                          Mark , WD4ELG


                          --- In hex-beam@yahoogroups.com, tim lindstrom <hambeemer@...> wrote:
                          >
                          > Goodmorning!
                          > Sunspots are kind of low. However my homebrew Hex at 20 feet has no
                          problem reaching europe. that is If I can find the time to play radio! I
                          live in the metropolitan area of Minneapolis MN.
                          > I did talk to Italy but that was almost 6 months ago.
                          > Would be nice to have this hex at 30 feet. Not sure if it will do any
                          better.
                          > tim lindstrom, ab0ts
                          > columbia heights, mn
                          >
                          >
                          > ----- Original Message ----
                          > From: John bicyclepeddlers@...
                          > To: hex-beam@yahoogroups.com
                          > Sent: Sunday, April 29, 2007 7:39:25 AM
                          > Subject: [hex-beam] Hex Beam - Effective height
                          >
                          > Hello,
                          > I have my 5 Band Hex on a home built 26 ft tower. Increasing the
                          > height of that tower is not possible at this time.
                          > My other tower is Rohn 45G at about 50 ft. Lowering it is possible but
                          > wonder if it's worth it? It now holds a TET 43SP which is outdone by
                          > the Hex.
                          > Would like to put the Hex on top of the 45G but the story line is that
                          > 40 ft is max height for the Hex. Are any of you operating with your
                          > Hex beam at 50-52 ft? If so, what results to you get?
                          > 72/73,
                          > John N0LT
                          >
                          >
                          >
                          >
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