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I wish to erect two separate antennas, one 20 meter dipole and one 40 meter dipole. My property has 3 trees that are the correct distance apart from each other. They are oriented such that when the dipoles are in place, one end of each dipole will be connected to opposite sides the same tree (the middle tree) and the two antennas will be at a 90 degree right angle to each other. They could easily be at different heights above ground.

My question is, will having one end of each antenna being only about two feet apart and being at almost perfectly 90 degrees to each other cause any problems?

Thanks!

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  • $\begingroup$ My gut feeling is that they will be fine. You slso might consider a fan dipole, where both antennas are parallel to each other, spaced apart, and are fed with the same feedline. $\endgroup$
    – Mike Waters
    Commented Jun 16 at 13:01
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    $\begingroup$ Why would you want to put up two antennas to double the cost and not buy yourself anything? You can put 20 and 40-meter elements on the same coax without issues. $\endgroup$
    – user23405
    Commented Jun 16 at 16:00
  • $\begingroup$ @Dereck That's why I suggested a fan dipole. However, it's possible that he's doing it to cover different directions (areas) on each band. $\endgroup$
    – Mike Waters
    Commented Jun 16 at 19:31
  • $\begingroup$ If I had EZNEC working here, I would have modeled the two antennas. :-) $\endgroup$
    – Mike Waters
    Commented Jun 16 at 19:32
  • $\begingroup$ Who said the two could not be in different directions? Think of an X orientation. The trick with fan dipoles is to separate the elements from each other. The two dipoles at right angles are as far apart as possible. $\endgroup$
    – user23405
    Commented Jun 16 at 23:58

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It sounds like your trees are a little too close together. If you're going to be transmitting with these antennas, keep in mind that the ends of the dipole are high-impedance points — high voltage and tiny current. You really don't want these points within one foot of a (grounded) tree trunk.

Your antennas should be constructed with an insulator at each end, with enough support wire attaching it to the tree to keep the active end well away from the tree and its foliage.

If you do this, your actual question becomes moot.

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  • $\begingroup$ Well, this is kind of obvious. I just assumed it was implied that there is extra room between the trees for the insulating support wires. $\endgroup$
    – Tony565
    Commented Jun 19 at 13:23
  • $\begingroup$ So then what exactly did you mean by "one end of each antenna being only about two feet apart"? $\endgroup$
    – Dave Tweed N3AOA
    Commented Jun 19 at 20:56

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