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Small tribander model

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by UA3TW, Jul 13, 2018.

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  1. UA3TW

    UA3TW Ham Member QRZ Page

    This is MMANA model of a tribander that has the size of a 15-10m dualbander that is added by 20m Moxon.
     

    Attached Files:

    SP3L likes this.
  2. UA3TW

    UA3TW Ham Member QRZ Page

    The first phase is over: the base dualbander is ready and well. On picture the SWR curves for 15 and 10 meters. Blue is MMANA simulated curve. Red is real measured curve at the height 10m over the roof. Measured through the coax repeater 13.8m long of the solid polyethylene (V factor 0.66) The antenna required no tuning after the model.
     

    Attached Files:

    Last edited: Aug 12, 2018
    SV1IYF likes this.
  3. SV1IYF

    SV1IYF Ham Member QRZ Page

    Nice design Nick,
    Thanks for sharing.
    73 Nikos SV1IYF
     
    UA3TW likes this.
  4. UA3TW

    UA3TW Ham Member QRZ Page

    Hi Nikos, I like MMANA because the built antenna coinsides with it's model 100 per cent. One can not simulate such an antenna in EZNEC, me failed at least.
    I hadn't attached the model of the base dualbander. Here it is.
     

    Attached Files:

    KE0EYJ likes this.
  5. KE0EYJ

    KE0EYJ XML Subscriber QRZ Page

    I miss my moxon. I took it down because it was a 20m on PVC and Fiberglass, without a true tower. I was worried about weight in spring typhoons. I replaced with a basic 2-el. The moxon was better, overall. I could also tune 17m from my 20m moxon, and it was still very effective.
     
  6. UA3TW

    UA3TW Ham Member QRZ Page

    Small pentabander model performance. The pentabander is having same footprint as the base dualbander.
     

    Attached Files:

  7. UA3TW

    UA3TW Ham Member QRZ Page

    It happened that the tribander from #1 has been working over almost a month and operated in a few contests but I couldn't measure the SWR reliably - had to build the SWR meter with mighty drive, othervice the nearby 9.5 kW FM station caused distortion.
    This morning I took IC-718 and the meter on the roof and did the measurements.
    On picture the blue line is the model SWR. The colored boxes are measured SWR points.
     

    Attached Files:

  8. UA3TW

    UA3TW Ham Member QRZ Page

    Today Roman RA3TE made pictures of the antenna. I attach one of them.
     

    Attached Files:

  9. KA2RRK

    KA2RRK Platinum Subscriber Platinum Subscriber QRZ Page

    Okay, I would like a pair of stacked pentagram antennas. I need it by October 26 @ midnight and it's okay
    also if it is covered with antique gargoyles...

    Here is a drawing of the antenna .


    KA2RRK prod_16334752210.jpeg
     
  10. UA3TW

    UA3TW Ham Member QRZ Page

    14 april I finished rebuilding the small tribander into small pentabander. 19 april Roman RA3TE took pictures of the antenna, 20 april I measured the SWR and compared it with model SWR. As expected the worst incoincidence
    took place for the bands 12 and 10 meters where the driven elements are "open sleeve" ones. Still the SWR is reasonably good everywhere and I let it be as it is. Even at 24990 the SWR is less than 2.
    It still remains to measure the radiation pattern but no go yet.
    Here I attach the MMANA model, the pictures and SWR curves where red are measured curves black are model curves. The MMANA model contains the comment in Russian and in English.
     

    Attached Files:

    KO6WB likes this.

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