Stainless steel vs copper for invisible antenna

Discussion in 'Ham Radio Discussions' started by KB7QPS, May 18, 2019.

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  1. KB7QPS

    KB7QPS Ham Member QRZ Page

    So, I am considering making an invisible antenna for our HOA-restricted property using 1/32" stainless steel wire rope (7 strand). I am wondering if there is any analytical information on whether it would work? I plan on running between 15 watts and 1000 watts of output power. I've never come across any design guidelines as to the minimum thickness of wire.

    I know that stainless steel is not as preferable for antenna material, but it would be a whole lot better than copper in the house, right? Any information on copper versus stainless steel for antennas?
     
  2. WZ7U

    WZ7U Ham Member QRZ Page

    You are doing the engineer thing here Greg; over-analyzing it. Copper will work just fine, for a lot less money and hassle. Smaller gauge wire works fine to full limit, it's the environment that messes with it. You know; wind, birds, etc. You put up a 14 ga stranded wire with gray insulation and most people will be hard pressed to see it at height. Wireman has lots of examples that would work fine and if high enough, xyl proof.
     
    W2AI, NL7W and KK5JY like this.
  3. WF7A

    WF7A Subscriber QRZ Page

    WZ7U likes this.
  4. W1VT

    W1VT Ham Member QRZ Page

    If you have an EZNEC model of a copper or aluminum antenna it is reasonably simple to model how it works with another material. The losses can be high.
     
    Last edited: May 18, 2019
  5. WD3N

    WD3N Premium Subscriber QRZ Page

    American Fishing Wire 1x7
    45# test 600 feet
    BCU45-7
    $27
     
  6. WQ6N

    WQ6N XML Subscriber QRZ Page

    I was looking for phosphor bronze kite wire. The same stuff that was used for the old Gibson Girl emergency box kite wire. Super small gauge, strong and corrosion resistant. I never considered copper fishing wire that is 20AWG. I settled on the 26AWG Poly-Stealth kite wire. It's a little more expensive and the breaking strength is #25. One can still see the wire when standing underneath and it was suggested to throw the wire in a box and spray it light/winter grey.
    I use the lengths suggested in the Balun Designs document "Wire Lengths for 4 and 9-1 ununs" of 53ft (with a 4:1 unun) and 124.5ft (with a 9:1 unun). So far my experience is with the 9:1 unun and the 124.5ft wire attached to a wooden fence with small 1/4 screws that are 6in. long using black tie-wraps with screw hole for mounting. I found that a manual tuner does better than a auto-tuner on 80m. I had set the power levels for 50w but have gone up to 70w on occasion. I have plans to test the 4:1 unun with the 53ft length while camping this summer. Park Rangers here will not let anyone connect/touch any wire or stay to the trees so I use a combo of a pushup mast and stacked 4ft. military tent poles. The coax line is the counterpoise with a 1:1 inline choke at the building/radio end. Not perfect by any means, but it does work.
    My concern with small wire antennas is for possible harm to the larger birds. Although the smaller birds will land on anything. Wind and elements for me are minimal. The sun will cook anything over time.
    I use 14AWG Flex-Weave and a OCF balun for a 40m OCF antenna (very happy with this antenna) which will handle more power than the smaller gauges (although not so stealthy).
    My challenge is finding a method of getting the wire up in the air without the aid of a tree or tower without being an eye sore. Nothing that can be seen is xyl proof (at least for me anyways). Always like to read others inputs. 73, JohnF
     
  7. WG8Z

    WG8Z Ham Member QRZ Page

    ^^^ What he said ^^^
     
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  8. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    https://thewireman.com/antennap.html

    534
    [​IMG]
    'Invisible' Toughcoat 'Silky' 26 AWG, 19 strand 40% copper-clad steel (OD 0.020") with the same jacket as 531 (Nominal OD, 0.050" including 0.015" jacket, but super small for that 'low profile' antenna or pocket 'weekender' long wire. Weighs less than one pound per 1000 feet! Not recommended for 160 meters.Break strength 25 lbs 0.28 0.25 0.23 0.22
     
    NL7W likes this.
  9. KK5JY

    KK5JY Premium Subscriber QRZ Page

    One thing to keep in mind about bare copper is that it will very quickly turn brown (and a little green) when exposed to the weather. That will render it at least as well-camouflaged as any other metal, and probably better than any other bare metal.

    Bare copper will also tend to corrode when exposed to the weather. That's usually not a problem, but for very thin wire, it might compromise the mechanical strength over time.

    Then again, if you buy a huge roll of it, let it corrode, and then replace it. :)
     
  10. WE4E

    WE4E Premium Subscriber QRZ Page

    I used 14ga thhn stranded in black for a 160m full wave loop. I can point to it and you'll have a hard time seeing it. I've only ever seen one bird light on it, and it was a hummingbird. $45 at Lowes for 500 feet.
     
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