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distance from tower to vhf/uhf vertical antenna?

Discussion in 'General Ham Radio Discussion' started by Alain Theriault, Aug 18, 2018.

  1. Alain Theriault

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    hello everyone..



    I'm a fairly new amateur radio operator and I've purchased a Comet GP15. I have a tower here at my QTH and I've side mounted the antenna. I'm at about 5 or so feet away from the tower. I've read that it needs to be a certain distance from the tower so it doesn't affect the performance as much. I'm not sire what the exact distance should be for optimum performance. I'm unable to mount the antenna at the top of the tower because I already have an antenna there. What are the affects of the antenna being there? Thanks for taking the time to explain and answering my question..

    Al
     

  2. nomadradio

    nomadradio Analog Retentive

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    Conventional wisdom is a half wavelength or more, pretty sure. Don't remember a rule for "optimum", just for minimum distance.

    Sounds like you're outside that guideline already. Should be good to go.

    73
     
  3. Hurricane145

    Hurricane145 Active Member

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    Around here there are some public utility services antenna towers with a few side mounted antennas. The side mounted antennas are not very far out from the tower, just a few feet.
    Do what you can and see how it goes. Maybe make improvements later on.
    Antennas don't have to be textbook perfect to work well. Since you are going to be using it for 2 or 440 FM mostly, the repeaters are going to be doing most of the work.
    You are probably not going to be doing any weak signal work on FM where you need to get everything you can from the GP-15.
     
    #3 Hurricane145, Aug 18, 2018
    Last edited: Aug 18, 2018
  4. Blackcat630

    Blackcat630 Sr. Member

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    My comet 333 is on a homemade standoff using 2 6ft angle iron pieces and some old mast pipe & ubolts. This puts it about 4-5 ft out in a southerly direction. Never had any reflect or swr issues. Seems to work just fine in all directions as it should..
     
    binrat likes this.
  5. Blackcat630

    Blackcat630 Sr. Member

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    I first thought I may experience a null on the comet vertical toward the tower (north) but nothing that I really notice.. The discone (scanner use only) is less than 3 ft off the side and it actually works a little too well. I have to attenuate certain channels to only hear local public service traffic and not stuff 40-50 miles away. 20180818_224652.jpg
     
    Shadetree Mechanic and fogdog like this.

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