Attic antenna - Foil on insulation

Discussion in 'TiVo Coffee House - TiVo Discussion' started by dfreybur, Jul 19, 2019.

  1. dfreybur

    dfreybur Active Member

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    Jan 27, 2006

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    We're building a new house and the insulation on the ceiling of the attic has foil.

    Does this mean we'll need to mount the antenna outside on the roof?

    We'll go tomorrow to measure the exact angle to most of the transmitters but I think the corner of the house in that direction is the opposite of the point the cable/network/coax enters the house. I didn't think to ask about that when we ordered the new construction.

    According to antennaweb.org we are antenna class yellow for most of the OTA channels we watch. I'll get a better antenna than that anyways. But it it would work in the attic that's the best choice.
     
  2. TivoJD

    TivoJD Active Member

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    I had a roofover done a year or two ago that has a foil/metallic barrier on the insulation pieces that they put under it. It killed my signal.
     
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  3. Adam C.

    Adam C. Active Member

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    There are too many variables for anyone here to give you a definitive answer. Strength of signal, type/size of antenna, length of coax, amplifiers, etc. You'll need to play around with the setup and see what works.
     
  4. dlfl

    dlfl Cranky old novice

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    You might get away with locating the antenna at the point closest to the antenna towers and running high quality coax across the attic to the drop point -- and possibly using an amplifier. As @Adam C. said, no one can predict performance in your situation.

    And then there are metal roofs. ;)
     
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  5. wizwor

    wizwor Well-Known Member

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    I suspect you are going to have to put your antenna on the roof. Blocked and bouncing signals could be a problem depending on the material.

    When I had my house sided, I asked the contractor for a section of the insulation so I could test attenuation. There was none. If the signal is important to you, and you are not willing to put the antenna on the roof, I would get some of the foil backed insulation and do your own test. If you are planning to have an antenna, have the builder run a lot of RG6 from your antenna's location to the place where they distribute service throughout the house. For instance, you might have him bring three in from the roof to the attic (uhf, vhf-high, and vhf low) so you can keep your splitters/joiners/preamps in the house. You might want to have a half dozen go from the attic to the basement. Have the electrician put an outlet wherever you plan to install hardware.

    Use a GPS [app] to get the coordinates of any likely location. Use TVFool to assess the general situation. The channel data is a little dated, but you can tell where the broadcasters are relative to your antenna and what is between you and them.

    Measure the attic and post a tvfool link then we can discuss antennas.
     
  6. DocNo

    DocNo Member

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    BTW - keep the foil insulation; it makes a dramatic difference on attic (and house!) temperatures. Do not bother with an attic fan - waste of power. Foil will do more than anything else.

    And as others said, foil will almost ensure you will need an external antenna. Oh well - it's not really that big a deal. The energy savings from foil will more than likely be way more important long term :)
     
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  7. Fernwood

    Fernwood Member

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    New build, absolutely install an outdoor antenna.
     
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  8. videobruce

    videobruce OTA is still alive

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    Install an outdoor antenna, period! New or old build. ;)
     
  9. wizwor

    wizwor Well-Known Member

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    My first antenna was installed in February during a winter storm that knocked out power and cable for a week. I hung the DB8 from the rafters with string and snaked a coax from the attic to my bedroom tv. Later that year, I installed a mast on the north peak of my house and put another antenna above the roof line. I had both antennas up for years -- switching to one while working on the other, trying out different antennas, or just messing around. I got an HDHomeRun so I could 'measure' the differences. A 91XG worked marginally better above the roof line and variations of a DB8 (I use a DB8e right now) worked marginally better inside the attic. When I sided the house, I permanently removed the mast. Even in summer, I prefer to open a door and climb some stairs to working on the roof. Of course, protected from the weather, I never actually have problems to work on. I can use inexpensive RCA pre-amps instead of metal clad outdoor equipment. Frankentenna would have been very expensive to build and maintain outside. Piece of cake in the attic.

    Lots of reasons to be open minded about antenna installation options. Pros 'walk the roof' to find a 'sweet spot'. No reason not to walk around the attic as well.
     
  10. BobCamp1

    BobCamp1 Well-Known Member

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    The OP is going to have to do this, because even on the roof the foil in the attic will most likely negatively impact his OTA reception.

    He'll probably end up putting the antenna on the corner of his house that is closest to the towers.
     
  11. Intheswamp

    Intheswamp Active Member

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    I agree that the antenna will need to be outside the new Faraday cage, er, I mean foil insulation. ;)

    But, I will say that it can make a difference, sometimes significantly as to the location of the antenna in regards to perimeter of the house. 10' left or right can make a notable difference (or not). Raising the antenna or lowering it 5' or so can also make a difference. Television signals are radio waves...that come is specific "waves". You want the wave to hit the antenna elements, not go above or below. Naturally obstructions, trees, mountains/hills, etc., come into play, too. A smaller antenna (set of rabbit ears?) attached to a long pole to move around the perimeter with might work to "fish" for a signal with. When you find a "hot" spot, and it works ok aesthetically and is practical then try your big antenna. Pay attention to whether your desired channels are low-VHF, high-VHF, UHF, or all three...purchase the appropriate antenna. I'm not crazy about TVFool's data, their database is out of date...it will not even show my strongest channel. :confused: It was great while its database was current, though!

    Best wishes on your antenna system *and* house!!!!
    Ed
     
  12. BobCamp1

    BobCamp1 Well-Known Member

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    It's worse than that. He's got crooked ground planes. The signal will reflect off of the roof back towards the antenna, creating interference. This can be mitigated if necessary by mounting the antenna perpendicular to the roof instead of the ground.
     
  13. Intheswamp

    Intheswamp Active Member

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    The roof will be sloping away from antenna if the antenna is ground mounted on a mast against an outside wall. Radio waves *should* hit the sloped roof at an angle to reflect them on beyond the antenna rather than back to the antenna. "Should" being the key word there...we really don't know. ;) But, it's all the more reason to "go fishing" around the perimeter to find the sweet spot for reception. By the time the signal gets to his "yellow" antenna location it will probably already have been bounced and reflected to the point that it will be trial an error to find a spot where a good signal can be received. Multi-path is a given so an antenna with good front-to-back performance (DB8e?) would be good. Lots of factors to consider. But, yes, the foil will have an effect...to what degree, who knows? :)
     
  14. mdavej

    mdavej Well-Known Member

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    I’m still not seeing how the foil could affect the signal at all. Every house I’ve ever seen had insulation on the ceiling, not the roof. So the antenna would be above the foil and would be unaffected.
     
  15. Intheswamp

    Intheswamp Active Member

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    I'm thinking a lot of construction now tries to insulate the roof before the heat gets into the large attic area. I know retrofit rolls of foil backed "bubble wrap" was available at one time to tack to the rafters. Rigid foil-backed styrofoam insulation is used, too. Heat would be trapped between the actual roof layer and the insulation...then vented to the peak of the roof where ridge vents are installed. I'm no builder and I'm sure that's a very crude not-very-accurate description that I gave but it's my take on it. Insulation on top of the ceiling is still done, too.
     

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