A New Technique in Ferrite Phase Shifting for Beam Scanning of Microwave Antennas

A reciprocal ferrite phase shifter for 3-cm wavelength has been developed which makes use of a new design technique for obtaining large phase changes per unit length by electrical means. The device consists essentially of a longitudinal magnetic field applied to a ferrite rod centrally located inside a rectangular waveguide excited in the TE10 mode. With a proper choice of rod diameter and impedance matching elements, phase shifts of greater than 250¿ per inch and variations in transmitted power of less than ±0.2 db have been obtained with external control fields as low as 60 oersteds. Zero-field insertion loss of less than 0.1 db per inch has been measured. These characteristics, along with its geometrical configuration and small size, make this electrically controlled ferrite device useful in the design of rapid-scanning antennas or any similar microwave system requiring phase modulation.