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directional FM antenna + omni-directional DAB/FM antenna spliced together on one coax (sopuli.xyz)
submitted 2 years ago* by to c/amateur_radio@lemmy.radio
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I’m considering building a directional FM antenna for an FM station that has almost no signal in most of the house. Otherwise I must put the receiver near the window and put the antenna in a specific position. (related thread)

At the same time I am also tempted to build a omni-directional FM antenna that would also suit DAB frequencies (if possible). Since I would prefer to only run one coax cable throughout the house I guess I need to know if the directional and omni-directional antennas can simply be spliced together to share the same coax.

Is that feasible?

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[–] 3 points 2 years ago* (1 child)

No, I don't think that would work. Combining two antenna in one coax would combine the waveforms, which could result in destructive interference and much less signal. Even in the best case, you would lose any benefit of the directional antenna.

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  • [–] [S] 1 point 2 years ago (1 child)

    Thanks for the tip. bummer to hear I have to run separate coax cables or come up with some kind of remote switch.

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  • [–] 2 points 2 years ago* (last edited 2 years ago) (1 child)

    A pair of diplexers (specific to the frequency ranges in question) would do the trick.

    But depending on what reception is like in your area it may be the case that your FM aerial fortuitously picks up sufficient DAB signal for a separate DAB aerial to prove unnecessary ?

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  • [–] [S] 3 points 2 years ago

    The idea would be to have one omni-directional antenna for both FM and DAB, and a separate directional one for one particular FM station that’s hard to get. Perhaps I should first build the omni-directional antenna -- and maybe it will prove good enough to pick up the one weak station. If not, then I would build a directional one.

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