Metal Roof vs Antenna

Discussion in 'Ham Radio Discussions' started by K8IYO, Jun 25, 2017.

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  1. KA0USE

    KA0USE Ham Member QRZ Page

    i've lived in old houses with 'tin' roofs. the sound they make when it rains really helps me sleep well.
     
    K4AGO likes this.
  2. KF5LJW

    KF5LJW Ham Member QRZ Page

    Pretty simple metal roofs are just like whole house generators. They put a great big smile on your face. When golf ball to tennis ball sized hail falls on your roof, you laugh at all your neighbors while their roofs are destroyed.

    When a hurricane or summer thunderstorm comes and knocks your power out for a week, you just laugh all day long looking out your window in a nice cool air conditioned home lit up watching your neighbors suffer through the heat and darkness.
     
  3. K4AGO

    K4AGO Ham Member QRZ Page

    A metal roof lasts more than 50 years. A composite roof is good for about 25 years.
    John
     
  4. KL7AJ

    KL7AJ Ham Member QRZ Page

    At that distance, I would suspect that it would not be much of a reflector UNLESS the roof happens to be resonant....not terribly likely My infallible opinion says you won't notice any difference at all. :) MCMV (My credibility may vary)
     
    K7TRF likes this.
  5. KA0GKT

    KA0GKT Ham Member QRZ Page

    Years ago, my Uncle had an 80 - 40 trap dipole a HyTower and a TH-6 on a crank-up tower. You could watch the VSWR shift on the dipole as the beam was rotated. Ron and I had a regular sked on 40 CW but his dipole wasn't tuned to the novice portion of the band. A slight rotation of the beam brought the VSWR down.

    A metal roof might change the resonant point of your antenna, or it might not. Either way the problem won't be insurmountable.
     
  6. KN6SD

    KN6SD Premium Subscriber QRZ Page

    The Tri-bander will electrically see the metal roof a little bit... Is the fan dipole running over the roof???
     
  7. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Yeah, you probably won't even notice the roof. Whether it impacts your antenna pattern is a different question and harder to assess but I suspect your antenna tuning will be fine or perhaps need only a small tweak.

    Our house has an all metal roof and my primary antennas have always been right up above the roof. I've found that on 20m and higher frequency bands I find that the antenna tuning is impacted if they're much less than about 10 to 12 feet above the roof but once I get that high or higher the tuning doesn't change. I've seen that with several different antennas I've had up there including dipoles, a Cobweb and a Moxon, lower them to less than 10 feet above the metal roof and the antenna tuning changes, but once they get up to 10 to 12 feet or so above the roof their tuning doesn't noticeably change as I raise them higher.

    I suspect you'll be fine with 25 to 30 feet of clearance to the metal roof.
     
  8. W5LZ

    W5LZ Ham Member QRZ Page

    Take this for what it's worth. I have used a dipole antenna that partial ran over the top of a metal roof. It had to be adjusted for that. but it worked just fine. At most there was maybe 10 feet of clearance maybe. That 'just fine' thingy amounted to making contacts, talking to people, etc. Was it the best that was possible? I really doubt it, but it was good enough. If you expect perfection you have some adjusting to reality to do. Sorry, but you ain't never going to see perfection.
     
  9. AG5WT

    AG5WT Ham Member QRZ Page

    I just installed a G5RV that was gifted to me on a standard tv antenna pole, about 25' at the feed point. One wire is sloping down over my house, coming about 2' above my metal roof at the closest point. The other line is in open air going to a nearby shed. It's the best I can do until I get a legitimate tower put up. I haven't been able to test it yet as my coax wasn't quite long enough, but I don't expect the performance to be that great. I also put a 2M/6M vertical ground plane antenna on top of the pole, and was able get a couple of contacts on a repeater about 70 miles from my location on 2M @ 20 watts with that antenna.
     
  10. WZ7U

    WZ7U Ham Member QRZ Page

    Since its been over two years since Cathy posted, I wonder how it went?
     

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