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Author Topic: Metal roof ground plane  (Read 7722 times)
N0NZG
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Posts: 115




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« Reply #15 on: March 08, 2013, 06:34:59 PM »

I used a 20m vertical on top of a 30x60 foot metal building and it worked like gang busters. The ridge cap with extra screws in it did a good job of bonding it all together. I have NEVR had a vertical work any better.  Corrosion from steel on steel joints even galvanized steel are unlikely to cause rectification issues and RFI. Aluminum connected to steel or any other dissimilar metal connections with corrosion will cause RFI issues.   
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KD2DBM
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Posts: 27




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« Reply #16 on: March 10, 2013, 07:54:20 AM »

Not for nothing, but I agree with those who are utilizing a metal roof for a ground plane. I have a 14 x 70 mobile home with a tip out and a 9 foot by 18 foot add on room, both, (tip out and add on room), having metal roofs. The main roof is asphalt shingled, I have a 5 BTV mounted on an old satelite dish mount on the edge of the shingled roof in between the tip out and add on room, (there is a 3 foot space in between the two to allow for access under the mobile home), and I worked Sweden with a 30 over signal last nite on 20 SSB.

No wire ground plane, no counterpoise. Now, it is possible I guess for the metal roofs to act as a counter poise but i doubt thats that's the case, but I could be wrong and would be the first to admit if that is the case. So, I believe a metal roof can be used as a ground plane. As an aside, each metal roof is 8 inches away at a 45 degree angle from the feed point of the 5BTV. 5BTV works BETTER than my 160 meter dipole which I put up in a triangle closed loop configuration on the west side of the shingled roof.

Just my 0.02 cents.

Bill, KD2DBM
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KQ6Q
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Posts: 965




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« Reply #17 on: March 11, 2013, 08:59:48 PM »

The factory (Bencher) suggestion about the small diameter wires under is all you need. I have a comparable arrangement - 24x56' mobile home with a metal roof. I use triple magmounts, with Hustler masts and resonators, and at least two radial-cut wires for the bands on the resonators (some masts have more than one) just laid out across the roof. Works well enough for me, the SWR is easily handled by the auto-tuner in my 746Pro.
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