Characterization of LTCC-Based Ferrite Tape in ${X}$ -band and Its Application to Electrically Tunable Phase Shifter and Notch Filter

In this paper, low temperature cofired ceramic compatible ferrite tape (ESL 40011) is characterized in X-band to study the properties of the tape in the demagnetized state. Data obtained are used to design an electrically tunable ferrite phase shifter and a tunable notch filter. These components are made electrically tunable by winding the bias coils around the ferrite substrate. They operate in the partially magnetized state at the magnetic fields <;100 Oe. This biasing mechanism eliminates the use of external biasing magnet for tuning. The phase shifter occupies a total volume of ~2 cm
³
including the bias circuitry and the test fixture. For a biased current of 700 mA, the measured differential phase shift of 215° having a figure of merit of 48°/dB is achieved at 10.6 GHz. Tunable reflection-type notch filter is designed using the same method of biasing. Center frequency of the notch is observed at 12.35 GHz. A tunability of 3.5% is achieved by varying the bias current from 50 to 450 mA. Simulation of the structures in a 3-D electromagnetic simulator shows good agreement with the measured results. High power measurements carried out up to a 2 W of input power show good stability in the performance of these components.