Hysteresis effects in non-reciprocal and rotary field ferrite phase shifters

Reciprocal and non-reciprocal ferrite phase shifters are commonly used in single and two axis electronic scanned phased array antennas where the individual elements operate at moderate or high peak and average power levels. Hysteresis effects can have a significant impact on the overall phase accuracy performance of the phase shifter. Factors influencing the phase error caused by hysteresis are discussed in this paper. Results are presented on two different classes of ferrite phase shifter, both operating with C band. The first is the classic non-reciprocal toroidal phase shifter and the second the reciprocal rotary field device. Different drive techniques for both phase shifters are discussed and measured phase errors presented. The results indicate that phase errors due to hysteresis can be reduced significantly at the expense of switching speed, power consumption and driver complexity. Furthermore careful selection of the region of the hysteresis loop in which the phase shifter operates can further reduce the error