Sunday, April 18, 2021

Antennas, Antennas, Antennas

  When the ES season will arrive exactly is always a surprise. But we expect it at the end of April, or sometimes earlier. So, this is the time to get the antennas ready. My 4 element LFA beam was in a state of pity, the front director and the reflector were both loose and shifted after the last storm. I borrow this LFA from the PA6AA contest group and had to ask the owner (PB7Z) if I could make some reinforcements since I'm not that impressed about the quality of this antenna. Bernard told me it is no problem at all. So a few brackets were fabricated to reinforce the mounting of the elements to the boom. 

The video shows what the problem is. Tightening the clamps will only give a temporary solution.



Solution made with extra clamps. This was made for the reflector and 2 directors.

I did another last experiment with my multiband vertical. I made 5 quarter wave counterpoises instead of using the tower as "countercapacity" for the vertical. It didn't seem to help at all. I see no difference in SWR and/or performance. The idea of cutting quarter wave wires for the vertical is not needed at all. You can do fine with just one wire and tune it with the autotuner, it will not make any difference in my opinion.

What I really want to try if time allows is the 5 band square halo PA9X experimented with. He wrote the antenna does better as his 5/8 wave vertical on 20m. I would like to confirm that and compare it with my multiband vertical. I have the parts.....but time is a issue. I want too many things.

Tower summer 2020

The 4/6m duoband beam has the same element mounting as the LFA. Though the elements are way shorter and weight a lot less. So, no problems with it at all. Besides that I don't have this beam up in the tower in the winter and storm season...


G0VXE's quad

I've been e-mailing a with a owner of a 5 band DK7ZB quad a while ago. Dave G0VXE has a beam like that on his tower. I've asked about some details for constructing one myself. He used capacitors made from coax to tune his reflectors. Tuning the reflectors will actually be the most difficult for this antenna. I'm not shure how to do it? Since tuning at low height will probabely not give the same results as if it is on top of my tower at full height. I probabely keep myself to the calculated lengths on the DK7ZB 5 band quad website, if I'm not satisfied with the f/b ratio I can always try to tune things. I might use a scaffold to get on the right height...

For those that question the ladderline he used at the director cross....it is for lineair loading and use on 30m. But it seems a full size dipole works better after all is what he told me.

That's me. To get an idea of the antenna size...

I wrote this blogpost mainly for myself since I've too many ideas. I don't want to forget what I learned and how I think about antennas right now. Originally I was planning to build the 5 band quad this summer. But I already see other more important chores coming. I might try a prototype square halo for 20m on a separate mast just as experiment.

Ready for the ES season 2021

6 comments:

  1. Some very impressive antenna work Bas and the picture of you and the antenna in the background sure brings things into perspective to it's size!
    73,
    Mike
    VE9KK

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    Replies
    1. And this is only the size of a 4m/6m beam and a 10m beam. Imagine a 5 element 20m beam, it's twice the size. It would be a big challenge to get such a antenna in my tower ;-). 73, Bas

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  2. Hallo Bas, lekker bezig. Je begint een echte pro te worden. Daar kom ik dan met m'n draadje. ;-) 73 Paul

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    Replies
    1. Ach Paul, pro niet hoor. Ik rommel ook maar wat aan. Maar houd wel van een experimentje. Het pakt niet altijd goed uit hoor. Maar de 6m/4m combi antenne heeft zijn kunnen wel laten zien vorig jaar. Dus we doen het nog een keer. Ik heb natuurlijk ook wel de ruimte hier. Maar ook met een draad kun je hele leuke dingen werken natuurlijk. 73, Bas

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  3. Bas, you have some really tall antennas there in the background. Are they on your property and available to use as supports?

    73,
    John

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    Replies
    1. Hello John, the trees are not on my property. However, if I would ask I think it would be possible to use them. I always ask my neighbours when I need to cut some branches from those trees overgrowing my garden. Till now I only used one tree to for experimenting loading it as a antenna. I probabely do that again somewhere in the future. But for now I have enough other experiments I want to do....73, Bas

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Thanks for your comment. Bedankt voor je reactie. 73, Bas