three-decibel coupler

three-decibel coupler

[′thrē ¦des·ə·bəl ′kəp·lər]
(electromagnetism)
Junction of two waveguides having a common H wall; the two guides are coupled together by H-type aperture coupling; the coupling is such that 50% of the power from either channel will be fed into the other. Also known as Riblet coupler; short-slot coupler.