Performances of the planar ferrite phase shifters based on microwave garnets

Control of the digital phase shifters can be achieved with help of a d.c. biasing magnetic field applied to a ferrite inside a rectangular waveguide. The garnet ferrites are used to manufacture tunable bandpass filters where the resonant frequency is tuned in order to obtain different vales of the phase shifting over the frequency band of interest. The Trans-Tech microwave garnets (calcium vanadium substituted YIG) were studied comparatively, in the planar phase shifter configuration, by simulation methods (HFFS Ansoft). Results indicate that the permeability evolution of the ferrite slab versus frequency can be shifted with circa 20 %, due to the dependence of the ferrimagnetic resonance on the biasing field (0-2 kOe) and also the insertion loss. The phase shifting is also a function of frequency, over the considered frequency band for tuning (4-12 GHz for the Trans-Tech garnets).