Spatial separation of undesired particle components from high energy kaon, pion, and antiproton beams is achieved by means of an rf separator consisting of two transverse deflectors, set 40 m apart and operated at 2.856 GHz. Elimination of two contaminants is possible if their difference in transit time between deflectors equals a multiple of one rf cycle. In the system described this occurs, for example, at 12.80, 9.04, and 7.38 GeV/c if kaons are desired. The actual useful beam system involves the magnetic optics necessary to form a momentum analyzed beam with &Dgr;p/p=1% and to transport the particles over 129 m between an external target at the Brookhaven Alternating‐Gradient Synchrotron and the 80 Inch Bubble Chamber. The design of the magnetic optics for the momentum analysis section, the separator stage, and the post analysis section is discussed. For proper operation, the rf beam separator described requires deflectors which are capable of imparting a transverse momentumpT≥18 MeV/c to traversing particles. A 3 m long iris‐loaded structure operating in a backward wave hybrid mode with dipole character was selected. The necessary multi‐MW rf pulses are generated by a microwave system which consists of a phase locked source, TWT, triode, and klystron amplifiers, as well as associated modulators. A phase servo maintains the prescribed phase relationship between deflectors. The separated beam has been tested and run as kaon and pion beams. The system has, in general, performed according to expectations. Preliminary performance data indicate for example at 12.8 GeV/c an average yield of eight K−mesons per pulse with 0±15% background.