Three New Ferrite Phase Shifters

Three new devices for the electrical control of microwave phase shift are discussed. The first of these, the bucking rotator phase shifter, is a reciprocal unit. It employs two series ferrite rotators, the field coils of which are connected so as to produce opposing longitudinal magnetic fields. It is shown that the total rotation is zero independent of coil current, whereas the phase shift is a function of the current. The operation and limitations of the device are discussed. Curves of phase shift vs coil current for several configurations are presented. The other two devices are based on the use of a circular polarized phase shifter between quarter wave plates. In the new types, a reflection technique is described wherein only one quarter wave plate is required and the phase shift section is used twice. A nonreciprocal phase shifter and an electrically controllable short circuit based on this technique are described. The principles of operation are discussed, and the devices are compared with other types as to performance, size, and bandwidth.