AM antenna out of RG-6 quad-shield coax?

Discussion in 'Home Theater Projects' started by RobertCharlotte, Sep 1, 2005.

  1. RobertCharlotte

    RobertCharlotte Supporting Actor

    Joined:
    Feb 21, 2002
    Messages:
    660
    Likes Received:
    0
    Trophy Points:
    0
    Pardon my electrical ignorance. [​IMG]

    I have seen kits like the Radio Shack 278-758 for constructing antennas, and I was thinking about trying to use this in my attic to get a nice, long AM antenna. Then I thought, what's to keep me from taking a nice long run of RG-6 quad shield coax, stripping 30 feet of it or so it to it's center conductor, and running it straight back to the receiver?

    So, my question is, what's to keep me from doing this? And if the answer is nothing, would the same sort of setup work for an FM antenna?
     
  2. chuckg

    chuckg Supporting Actor

    Joined:
    Apr 27, 2004
    Messages:
    917
    Likes Received:
    0
    Trophy Points:
    0
    That would work fine. A "long wire" antenna is just that - a long wire. You don't even need to strip a long piece of coax, you can just use any old wire tied to the center conductor of the coax. You could use a piece of non-stripped coax, and tie the shield of the "antenna" part to the center conductor of the "run to receiver" part (leaving the "run to receiver" shield not connected)

    An FM antenna is usually a bit more complex, but a long wire will work. You can bring your "run to reciever coax up into the attic, then run a wire from the center conductor ten feet in one direction, and a wire tied to the shield ten feet the other direction and make adecent FM antenna. This might be a bit too directional, though.

    AM and FM stations are usually so powerful that you don't need much antenna, unless you live in the boonies or something. Experiment and see what works! That's how Marconi did it.
     
  3. Elmer Millikan

    Joined:
    Oct 8, 2002
    Messages:
    49
    Likes Received:
    0
    Trophy Points:
    0
    Sorry to pile on here but I have a related question I have meant to ask for some time. I have a Halo T3 tuner in my media room (basement) that I get crappy reception for. I also have an Winegard rooftop antenna for my hdtv reception. Can I split this cable and run one to the T3 for FM radio reception?

    Thanks.
     
  4. Joe L.

    Joe L. Stunt Coordinator

    Joined:
    Oct 18, 2003
    Messages:
    104
    Likes Received:
    0
    Trophy Points:
    0
    If the antenna on the roof used for HDTV is a UHF antenna it probably will not be very effective at FM radio frequencies.

    To be effective for FM it needs to have elements about a 1/4 wavelength long at 98MHz (approx. middle of the FM band)

    Wavelength (in meters) = 300 / frequency (MHz)

    a full wavelength would be roughly 3 meters for the middle of the FM band (300/98) and therefore, to work well in the FM band the elements would need to measure about 1.5 meters (4.9 feet) from end-to-end, or .75 meters (2.5 feet) from the center where the coax connects to each end.

    Joe L.
     

Share This Page