Wire antennas in trees

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KG4DYN, Dec 31, 2019.

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  1. KG4DYN

    KG4DYN Ham Member QRZ Page

    Happy New Year all! I have some questions about wire antennas and contact with trees, tree limbs, etc. I hope I don’t get flamed for asking these questions (it happened to me before on a different topic). I was out surveying my trees this evening for future antennas since the leaves are off and I can see everything. I live on a small ridge in the middle of oak woods. I have some beautiful trees for wire antennas, but the problem is, there’s a lot of them. And a lot of limbs to work around. I currently have an OCF dipole in an inverted V configuration with the balun at around 42 feet. It works OK, but I want to eventually upgrade to a similar dipole that can handle an amp, and an inverted L for 160 meters.

    My questions are: Do trees limbs contacting wire antennas cause issues at HF frequencies? Could wire contacting small limbs cause problems with high power (1000+ watts). To build an inverted L is it OK for the wire to contact the tree on the vertical part or should it be not contacting the tree at all? I have considered a vertical but it would be almost impossible to run radials straight and they would have to contact roots. Would this be OK for radials?

    I appreciate any suggestions and advice.

    Doug
    Kg4dyn
     
  2. WT4W

    WT4W XML Subscriber QRZ Page

    I've always used THHN insulated wire, and with an 800 watt amplifier have never seen any issues.

    The biggest chance of problems will be at the high voltage points (the ends of a conventional dipole). I've always made sure I have some separation between the ends of my dipoles and any trees.

    As for radials, I can't imagine that coming into contact with roots would be an issue.
     
    WB5THT and KB3UWC like this.
  3. WB5THT

    WB5THT Premium Subscriber QRZ Page

    I have an end fed dipole draped over oak trees and 800 or 900 watts does not seem to impact them in any way.
     
  4. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    This topic was discussed about 3 weeks ago and detail do a search you'll find lots of good answers
     
    AK5B and KG4DYN like this.
  5. N1OOQ

    N1OOQ Ham Member QRZ Page

    AK5B, KG4DYN and K0UO like this.
  6. KG4DYN

    KG4DYN Ham Member QRZ Page

    Thanks guys! I found the previous discussions!

    Happy New Years!
    Doug
    Kg4dyn
     
  7. KC8QVO

    KC8QVO Ham Member QRZ Page

    I have 150ft of wire, end fed with a remote tuner, going up in to 2 trees. The run to the first tree is a bit of a low angled sloper. Then the antenna bends 90deg for the rest of the run. I have it held up with braided dacron fishing line (30-50lb test I think). The wire is resting against part of the AC, the roof, and the last tree (there is enough slack in the support line in the 1st tree that the wire is held out of the branches - the last tree is too close to do the same when I originally put the antenna up). It runs the low bands fine.

    If you are going to put up a big antenna for low bands (specifically 80 and 160) and you are in a wooded area I would highly recommend using a copper clad steel wire. The reason for this is branches and limbs come out of trees quite frequently. With a light wire you can run in to problems with things breaking easier. From a strength perspective - 14 or 12 gauge solid copper clad steel would be my ideal recommendation. However, you aren't likely to find that as insulated wire. If insulation is important then you may look in to Silky Wire from The Wireman. It is jacketed copper clad steel stranded wire with a high break strength. You can get it in 13 gauge with a 400lb break strength.

    https://thewireman.com/product/antenna-wire-13-awg-copper-clad-steel-stranded-jacketed/

    I have a spool of the 26 gauge Silky wire (what I made my wire antenna from, as well as a few other portable antennas over the years) and a spool of the 18 gauge. I have had plans to build a field day jumper dipole with the 18 gauge that runs 160-20 meters or so. One of these days. Thing is I need to be somewhere where I can put it up to build it - and I can't put it up here.

    On a side note - somewhat related to the strength point above and breakage - another thing you should consider is that copper can stretch. I'm sure someone will post on here about how their solid copper or stranded copper THHN wire has been up for 15 years without much trouble. However, any type of all copper construction (hard drawn copper, what have you) will stretch over time just by being in the air. If you have anything that falls on it (tree limbs) - if the event doesn't break the antenna it will strain connections and the wire itself, stretching them, and weakening them some. Over time that will cause the antenna to fail. Copper clad steel is your best defense against this - in any form, though solid wire is the best (heavier and harder to work with, but it will be the strongest). Below is an example:

    https://thewireman.com/product/antenna-wire-12-awg-copper-clad-steel/
     
  8. K8JD

    K8JD Ham Member QRZ Page

    Almost all my current HF antennas have portions of the wire draped over tree limbs up a high as I could get them. They are mostly Coax fed dipoles so I have the far ends well inslulated and tied off with rope. The Wire is 600 Volt rated THHN insulated #16. I have no problems with them.
    One more antenna is a 40 M horiz square loop antenna and there are likely to be several high voltage points on the wire but have seen no arcing thru the insulation to tree limbs yet.
    I use a 6 position coax switch to accomodate most the coax runs coming into the radio room.
     
  9. KG4DYN

    KG4DYN Ham Member QRZ Page

    Thanks for the great info. I didn’t think it would be an issue at 100 watts pep, but wasn’t sure about higher power. I think I’m going to build a 160 meter inverted L soon. My plan is to shoot a messenger line through the fork in a nice, high white oak for the vertical and then run the remaining horizontal length to another tall white oak with 550 cord.
     
  10. BG4INK

    BG4INK Ham Member QRZ Page

    新年快乐Happy New Year
     

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