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MP3 Automotive Antenna

Discussion in 'Radio and Communications' started by TP380Z, May 9, 2016.

  1. TP380Z

    TP380Z New Member

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    Location:
    Fort Erie, ON
    I have an AM radio in my 65 Barracuda that I've upgraded with an Aurora Design FMC-1 FM tuner. This upgrade also includes an auxiliary input that I'm planning to use with my MP3 player. The radio shop will add a couple of RCA female jacks for the auxiliary input and I need to get a cable with male RCA plugs on one end and a 3.5mm plug on the other.

    My MP3 player (a smart phone) has a built-in FM tuner that uses the headphone cord as the FM antenna. While it's redundant to have both, I thought it might be more convenient sometimes to leave my radio in auxiliary mode and use the phone's FM tuner instead.

    When I search for suitable adapter cables, I see that they are generally available multiples of 1m and a 1m would be a good fit in my application. Would there be any advantage with respect to FM reception by using a 2m adapter cable instead?
     
    Last edited: May 10, 2016
  2. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    Your smart phone FM tuner will not work properly without an external antenna mounted on the outside of the car. The wavelength of the radio signal at FM frequencies is about 3meters. The windows into a car (with the possible exception of the windshield) are less than 1/4 wavelength across, and they greatly attenuate the FM signal. The car body makes a very effective Faraday cage. For a radio wave to propagate through an opening in metal, the opening must be > ~1/2 wavelength.

    I know this from trying to transmit/receive from inside a car or aircraft using a 147MHz VHF walky-talky (adjacent to the FM band, wavelength is 2m) .

    Receiving FM broadcasts inside my all-metal aircraft hangar doesn't work well either, at least not until I open the hangar door, which is about 7 wavelengths across at 100MHz
     
    Last edited: May 9, 2016
  3. TP380Z

    TP380Z New Member

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    A 1m long cable should reach from the top rear of the radio all the way up to the top of my dash board so it would seem to be the neater length.

    Many years ago, we got the kids each an FM radio from the dollar store. With the headphone cord/antenna, their radios seemed to work well enough inside the car so I figured the FM tuner in my phone would work at least as well.

    Would there be any way to connect the adapter cable to my car's external antenna?
     
  4. dave

    Dave New Member

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  5. Mikebits

    Mikebits Well-Known Member

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    I tried to view the FMC tech manual in order to see the best way to connect your external ant. but to do so requires a password :banghead:
     

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