I understand the reason repeaters can't operate simplex transmitting and receiving at the same time is because they will pick up their own signal. Lets say two people are on different sides of a mountain and 2 Uni-Directional antennas were pointed two different directions, one for each side of the mountain.

Would this enable SIMPLEX same-time repeating or would it be impossible to filter out the signal from the other antenna?

  • $\begingroup$ I believe the term you are looking for is "passive repeater". $\endgroup$ – user Nov 17 '13 at 13:03

"Uni-directional" antennas are usually not truly "uni"-directional - that is, they don't only radiate signal in a single direction. Instead, they radiate much more strongly in their frontal direction, with a weaker degree of radiation in other directions.

As such, if you have two uni-directional antennas near each other but pointed in different directions, you're still going to get signal between them due to their relative proximity. You could try to diminish the signal still further (e.g. by placing other things that would block the signal between the two antennas to further attenuate strength), or you could try spacing the antennas further apart (perhaps via feed lines) to put the mountain itself between them, but just having two separate antennas would not be enough.

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  • $\begingroup$ I guess parabolic dishes could get you pretty close, but that's probably not what the OP has in mind. $\endgroup$ – user Nov 17 '13 at 13:03
  • $\begingroup$ @MichaelKjörling Most of the parabolic dishes I've seen have in the vicinity of a 30-35 dB front-to-back ratio. So yeah, closer, but still not perfect. $\endgroup$ – Amber Nov 17 '13 at 17:44

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