Abstract: A four-state phase shifter for UHF waves comprises two O-.pi. phase-shifting elements of planar structure on a common substrate, these phase-shifting elements including a symmetrical and an asymmetrical transmission line which can be selectively coupled in one of two ways by the alternate blocking and unblocking of respective diodes for a relative phase reversal. The two phase-shifting elements are linked by two further transmission lines of different propagation constants which can be selectively activated, again with the aid of diodes, and which may be disposed on opposite faces of the substrate or may form part of a coplanar conductor array on the same substrate face.