oh wow, this is like an RF Circulator - https://en.wikipedia.org/wiki/Circulator - which are wacky enough in themselves.
> three- or four-port device that only allows a microwave or radio-frequency (RF) signal to exit through the port directly after the one it entered
Perhaps only superficially related (IANAElectricalEngineer) but that makes me think of multi-phase mercury arc-rectifiers.
https://en.wikipedia.org/wiki/Mercury-arc_valve
alt Hacker News
> three- or four-port device that only allows a microwave or radio-frequency (RF) signal to exit through the port directly after the one it entered
Perhaps only superficially related (IANAElectricalEngineer) but that makes me think of multi-phase mercury arc-rectifiers.
https://en.wikipedia.org/wiki/Mercury-arc_valve