Metal Roof vs Antenna

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

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  1. K8IYO

    K8IYO Ham Member QRZ Page

    I have a tower 45 feet tall with a 3-element tri-bander and fan dipole at the top by another foot or so. A few more feet up is a 2 meter vertical. I'd like to put a new metal roof on my home but am concerned how this will affect radio operations. The antenna is probably 25-30 feet above the pitch of the roof. Will I still be able to operate effectively?

    Cathy, K8IYO
     
  2. KY5U

    KY5U Subscriber QRZ Page

    My guess is it will be a bigger factor on 40 meters where 32 feet is a quarter wave. Might be a big reflector. Above 40 meters it may effect your swr. Some folks here may have more experience with metal roofs.
     
    K8IYO likes this.
  3. WA9WVX

    WA9WVX Ham Member QRZ Page

    Hello Cathy,

    Depending on where your tower and antennas are in relationship to the Steel roof, i.e. located near the back of your house or along side the house (if the 45' tower is bracketed to the house) you may find that the Steel roof may effect the direct of the RF signal. I wouldn't worry that much about this taking place because of the distance between the antennas and the roof line is 25 to 30' for the TriBander. As far as your fan dipole it may effect the VSWR, again depending on where those wires are located, i.e. strung across the roof wouldn't be the best situation. You shouldn't have any problems with your 2 m vertical.

    Dan
    WA9WVX
     
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  4. W5TTP

    W5TTP Ham Member QRZ Page

    When, and if you do, go forward with the roof project, please report back on your experience. After operating for a while on you favorite bands, you should, hopefully, be able to share with us some comparisons. Looking forward to it.

    Chuck
     
    K8IYO and K2HAT like this.
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I doubt it will really make any difference.

    The "ground reflection" we gain with horizontal antennas like dipoles and beams is based on "earth" going out many wavelengths beyond the antenna installation point, not directly beneath it. What's directly beneath the horizontal antenna may impact NVIS, which is pretty much a "10 MHz and below" propagation method, and the metal roof might actually improve that if you work 30/40/60/80 meters -- but probably not notably. Often, the critical frequency for NVIS is below 40m (like 5 MHz and down).

    Don't sweat it, I doubt you'll notice any difference at all.
     
    K0UO, WE4E, AE9AM and 1 other person like this.
  6. KD4CX

    KD4CX Premium Subscriber QRZ Page

    I have a metal roof with a Hustler BTV (10-40 meters) installed on the roof. It seems to work well. I have been told the metal roof acts as the needed radials. I wouldn't worry about it. I am sure the home is more important than ham radio so take care of the home then worry about the ham radio. You can probably modify the radio equipment a lot cheaper than you can a house unless you have other options.
     
    K8IYO likes this.
  7. KM1H

    KM1H Ham Member QRZ Page

    At a past work location the radio club installed a 30' tower and TH-7 in the center and over a metal roof 12 story building. Performance was dismal on DX and USA contacts.

    Moving it to a corner edge opened up a new world over that azimuth range.

    A vertical will work fine over metal as it establishes a conductive ground reference and reduces ground losses. A horizontal sees the metal as ground and the antenna performs as a 30' should.....poorly compared to the actual 150' height over real ground down in the parking lot.

    Carl
     
    K8IYO likes this.
  8. K7MH

    K7MH Ham Member QRZ Page

    I am just wondering why a metal roof is chosen over a composite roof. I know they are much more expensive usually. In my neighborhood there is only one metal roofed house. I don't think you see metal roofed houses around here very much.
     
  9. KA4DPO

    KA4DPO Platinum Subscriber Platinum Subscriber QRZ Page

    One thing to keep in mind here. A metal roof can be seen as a sort of artificial ground and can cause unwanted current to flow on the coax shield (ground loop). If you do not already have a Balun at the feed point of your antenna I would recommend that you install a 1:1 current Balun (line isolator) at the feed point. The W2DU isolators are good and can take full legal power without getting warm.
     
  10. KI5BLJ

    KI5BLJ Ham Member QRZ Page

    Here in SCentral Texas, golf ball to tennis ball size hail is regular occurrence. Hail this size tears up an asphalt roof very quickly and insurance won’t cover it if the damage happens more than once every five years. Metal roofs only dent which only affects their appearance so are ideal for protection from hail. We’ve had 4+ damaging hail events at my house in the last 6-7 years. I switched to metal roof after the first time it happened to me. I saw all the asphalt roofs getting replaced and no damage at all to the metal roofs, so do the math, metal roof always works out cheaper.
     
    ND6M and WA9SVD like this.

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