Three-terminal magnonic demultiplexer, power divider, and circulator

•A conceptual prototype of a three-terminal magnetic device with three functions is presented.•These magnonic functions are realized in the “tuning fork” shaped magnetic waveguide through the chiral spin wave modes.•The function of demultiplexer: the dual-frequency spin waves can be effectively separated into the two fork arms.•The function of power divider: the single-frequency spin wave can propagate into fork arms with equal amplitude.•The function of power circulator: spin waves in different ports propagate nonreciprocally with a field-controlled chirality.