3.7¿4.2 GHz 90° coaxial ferrite differential phase shifter

Nonreciprocal ferrite phase shifters usually rely for their operation on the two different scalar permeabilities exhibited by counter-rotating circularly polarised magnetic waves in a magnetised ferrite medium. One classic way to establish planes of circular polarisation in a coaxial transmission line is to partially load it with a dielectric material. Although this structure has been widely used in the construction of coaxial resonance isolators, it has not been experimentally employed in the design of nonreciprocal ferrite phase shifters. This paper describes the development of a 3.7¿4.2 GHz 90° phase shifter with a figure of merit of 600°/dB using a half-dielectric-filled coaxial line suitably loaded with ferrite sheets.