End fed wire from attic to outdoors?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by AE4CH, Jun 11, 2021.

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  1. AE4CH

    AE4CH Premium Subscriber QRZ Page

    On a thread here the recommendation was made to use an end-fed wire antenna as a simple HF solution.


    In my home, I imagine I could set up a HF transceiver in the office, and run a coax through the wall up into the attic. There, at the peak of the roof inside the attic, I have a gable vent panel where I could mount the end-fed hardware.

    From that high point, estimated to be at least 33 feet from ground level, I think I could string the antenna wire parallel to the roof truss, below the shingles and plywood decking, inside the attic, then out the roof at the soffit ventilation gap below the aluminum gutter at 90 degrees to the gutter. From that two-story point, the antenna wire would continue downward along the roof line angle (7/12 pitch) to a tree where it would terminate about 12 feet off the ground.

    I'm sure that this mounting would physically be possible, but you all would know if it would even work on 10-40 meters. Looking forward to moving into HF and trying hard to avoid causing concerns from HOA and neighbors.

    Is this concept at all workable?
  2. KC3PBI

    KC3PBI Ham Member QRZ Page

    I think that antenna set-up will work fine for radio purposes, but it's asking for trouble vs. lightning.
    N0TZU, AE4CH and AK5B like this.
  3. AK5B

    AK5B Ham Member QRZ Page

    Of course it will work; as always the question is how well?

    My main concern would be the earthing of your antenna system since it will going outside of your home (and kind of asking for feelers in the process).

    NEC has certain requirements that must be met if you want your insurance to cover any damage from lightning-induced surges or static discharge.

    Read the grounding stuff thoroughly here and in the General Technical Questions forum, too---lots of solid info there.


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  4. K6GBW

    K6GBW Ham Member QRZ Page

    That antenna is just a non-resonant wire with a 9:1 transformer. If you run the wire away from any metal and use at least 35' of coax it should work. You never mentioned the wire length? Is it possible to mount the transformer under the soffit and run the wire from there? That's what I did and it worked well. Keep in mind that non-resonant wire antennas generally have a high SWR and that is normal. You are meant to use an external tuner to bring it down.

    Attached Files:

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  5. WA7ARK

    WA7ARK Ham Member QRZ Page

    Last edited: Jun 11, 2021
    WB5YUZ, N0TZU and AE4CH like this.
  6. W3TKB

    W3TKB XML Subscriber QRZ Page

    Although not identical, my first HF antenna was a wire strung up in my attic. Performance was lackluster and rather disappointing. Once I removed it from inside the attic to outside, setting it up in a simple sloper configuration, my results vastly improved. Even though I had absolutely no metal objects in my attic or along the roof (other than nails) to contend with, the wood and asphalt shingles imposed a detrimental effect to performance.

    I would recommend trying to get your antenna entirely outdoors, or at least as much as possible, more being better than less. Good luck.

    WA8FOZ likes this.
  7. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page


    The antenna system you propose is very difficult to ground for safety. So, instead of trying to put the feed point and coax inside the attic, keep it outside and run the coax down the outside of the wall to the ground. There you can do a proper code-compliant job of grounding it before it enters the house and then continues to the radio room.

    Get a copy of the ARRL book on Grounding and Bonding for Radio Amateurs which will explain in detail why and how to do it correctly to meet or exceed code. The “sticky” thread at the top of this forum has a list of that and many other good resources to help.( And of course many here can help explain things too.)
    Last edited: Jun 11, 2021
  8. K6GBW

    K6GBW Ham Member QRZ Page

    WA7ARK, I see that I read it wrong and he has an EFHW. Regardless, the point was how to mount it and the referenced picture was for the purpose of mounting.
  9. AE4CH

    AE4CH Premium Subscriber QRZ Page

    I appreciate the safety insights! Being new to all this I do need guidance. I like the idea of the EFHW antenna, and have been looking at the house exterior now as the mounting point for the black box. Looks like at the gutter it would be only about 21 feet above ground. I did find a point at the back fence where I could raise a mast to which the free end would be affixed, perhaps 15 feet above ground. I can easily run the coax from the office bedroom up into the attic and across the floor to the soffit vent and outside the home there. I can also hide a ground wire at the corner of the house if that would be appropriate, dropping the ground from the black box down the siding. I'll look at the safety / grounding references you have given!
  10. W9WQA

    W9WQA Ham Member QRZ Page

    life's a gamble, full of risks. for 15 yrs i had a wire only leave a tuner on an outside wall .2nd floor.
    it went ? 88 feet to a weed whacker pullup in a tree,
    tuner did 160 thru 10,sometime 6.
    im surrounded by tall trees. wire 16 ft up max worked 360 degrees. no ground of any type.
    no baluns.
    counterpoise was the big soffit above the wire !!
    no hits...!
    after 16 yrs, whacker broke. gotta string it up again.

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