Development of high frequency ferrite phase-shifter

A phase-shifter was fabricated on a c-texture Zn/sub 2/Y (Zn/sub 2/Ba/sub 2/Fe/sub 12/O/sub 22/) single crystal substrate, and tested over microwave frequencies from 2 to 35 GHz and for biasing magnetic fields from 0.2 to 5 kOe. The differential phase-shift rate was 90/spl deg//kOe.mm at a microwave frequency of 20 GHz and a magnetic bias-field of 1.3 kOe. This device showed that it is possible to reduce the bias-field requirement efficiently and simply by utilizing the large in-plane anisotropy in Y-type hexaferrites and magnetostatic modes. A simple model based on the conjugate method for a TEM wave gave a reasonable match with the measured performance of the device, when the uniaxial magnetic anisotropy and magnetostatic modes were included.