Precise Control of Ferrite Phase Shifters

Hysteresis and thermal drifts can prevent accurate calibration of ferrite phase shifters. To provide a precise setting of phase in response to a control signal a servo system has been developed. This system utilizes a control frequency to determine uniquely the phase shift in a ferrite element. The desired phase shift is then a function only of control frequency and line length. Performance data are given for various operating conditions of the control system.