Can I use a 5/8th wave vertical designed for 6 metres on other bands?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by 2E0CIT, Jun 29, 2020.

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  1. 2E0CIT

    2E0CIT Ham Member QRZ Page

    I am planning changes to my tiny overcrowded urban antenna farm and have limited options as to how many from my collection of antennas I can put up.

    Scanning my vertical 5/8ths-wave antenna built for the 6 metre band I found it has the following swrs:
    1.5 to 1 on the 10 metre band
    1.5 to 1 on the 15 metre band
    3.5 to 1 on the 12 metre band
    5.0 to 1 on the 30 metre band
    -easily tunable with my atu and using 30 metres of low-loss Westflex 103 coax (though the above readings were taken only 7 metres from the feedpoint.)

    But I realise that low swr is not an indicator of efficient radiation for dx.

    1) Can I use the 6 metre band antenna on any of the of the above bands and expect a good dx radiation pattern or should I also put up my 10 metre band vertical half-wave, etc? (My knowledge of antenna modelling is at the pre-nursery stage!:()

    2) Also, knowing nothing of propagation modes on the 6 metre band, is the 5/8th wave vertical antenna good for dx or would a simple horizontal dipole or loop be better? Currently on a good day and using less than 50 watts from QTH London, it hits stations across Europe, Scandinavia, West coast USA / Canada... and once it even hit Puerto Rico:)

    73 y'all Jeff
     
    Last edited: Jun 29, 2020
  2. KJ4RT

    KJ4RT Ham Member QRZ Page

    I am also going to be interested in this answer. Also what gain if any at the design frequency of 52 Mhz?
     
  3. AF7ON

    AF7ON Ham Member QRZ Page

    It's usual to feed a 5/8 wavelength vertical with a base inductor - usually tapped for best match. This could be the limiting factor in feeding the antenna on other bands. Having said that, the main antenna itself is about a third wavelength on ten meters and about a quarter wave on fifteen. With added radials and attention to matching, it could work acceptably on those bands. It'll get progressively less efficient as the frequency of operation is lowered.

    Most 6-meter operators prefer to use horizontal antennas - I had a home brew-three element beam that wasn't a lot bigger than a TV antenna and worked extremely well. even a Moxon would work better than the 5/8 vertical for DX, in my experience.

    Mike
    AF7ON
     
    AJ5J likes this.
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    When propagation is favorable, or if the "other station" has a great setup (mostly antennas), all kinds of good stuff can happen.

    The advantage of a horizontally polarized antenna sufficiently elevated above ground is it has additional gain (even for a simple dipole) a vertical cannot have, due to ground reflection reinforcement. That happens with all horizontal antennas, but the reinforcement and gain achieved may not be at a favorable radiation angle for "DX" until the antenna is 1/2-wavelength above ground, and 1-wavelength is somewhat better, although that splits the gain lobes into two angles (one which is very low, and good, the other is much higher but can also be good).

    From the U.K., the contacts you mention are "farthest" to the U.S. west coast...Puerto Rico is much closer.
     
  5. KB7WG

    KB7WG Ham Member QRZ Page

    I did for several years in the 70s. I had a radio shack 5/8 ground plane for cb. I only had 10 meter and 40 meter crystals for my heath-kit dx-60. That antenna was fabulous on 10 and 40 meters. I sure wouldn't be afraid to try it. My experience tells me that vertical is best for long skip.
     
  6. 2E0CIT

    2E0CIT Ham Member QRZ Page

    Thanks, I note your comment about additional gain of a horizontal at a half-wave / full wave above ground level, I have a TV antenna rotator so am minded to set up one for 6m and do some comparisons with the 5/8ths wave vertical.
    As for working other bands using the 5/8ths wave for 6 metres....it works ( in terms of low swr)... but I'm but still interested in finding out the radiation elevation angle of its non-6 metre bands radiation as compared to using a dedicated vertical for each band. I guess I'll have to learn how to use MMANA properly to find out! 73 Jeff
     
  7. WA7ARK

    WA7ARK Ham Member QRZ Page

    How well the 6m vertical antenna radiates on the other bands depends a lot on its elevated radials. You didn't describe that aspect of the antenna. A picture would help, as would the height of the base, the number, length, and orientation of the radials, etc.,.,.
     
  8. 2E0CIT

    2E0CIT Ham Member QRZ Page

    Thanks Mike, Your info that most dx operators use horizontals on 6m is noted.
    So maybe the 5/8ths wave 6m vertical was designed for local ops on FM...not DX on SSB though it is supposed to have a low-angle output suitable for dx albeit with vertical polarisation, though not knowing much about VHF propagation I wonder if the polarisation is changed by the signal path the same way HF polarisation is changed or if my signals are staying vertically polarised when they are (poorly) received by other stations' horizontal antennas.
    A moxon on my TV antenna rotator could be fun!
    (The 6m vertical feeds OK on 10m, 15m, 12m ..in terms of low swr...and I have reasonable PSK Reporter hits, but I was wondering what the elevation angle of those bands would be from it compared to elevation angles from dedicated antennas for each band.)
    The question motivates me to get my head around modelling software,-so far I can just do simple dipoles on MMANA....but there's hope for the future!
    73, Jeff
     
  9. 2E0CIT

    2E0CIT Ham Member QRZ Page

    Hi Mike,
    The antenna is currently fixed on a pole, the antenna's base is 6 metres above ground level.
    It has 4 radials set at 90 degrees to each other and they are 90 degrees perpendicular to the length of the antenna. It has a coil of maybe of 3 turns. As it is currently too high for me to climb up and measure I can't say how long it is. Each radial is around 90 cm long.
    I attach photos but realise now that without offering accurate info I cannot expect accurate answers to my questions! Thanks for trying! 73 Jeff
    IMG_20200630_181038.jpg IMG_20200630_181038.jpg IMG_20200630_181229.jpg IMG_20200630_181603.jpg IMG_20200630_181615.jpg IMG_20200630_181628.jpg IMG_20200630_181229.jpg IMG_20200630_181603.jpg IMG_20200630_181615.jpg
     
  10. KI8DJ

    KI8DJ Ham Member QRZ Page

    I think the matching coil acts as a loading coil on 10 meters. Don't know about the other bands though.
     
    2E0CIT likes this.

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