Tunable non-reciprocal ferrite loaded SIW phase shifter

In this paper a tunable non-reciprocal Ferrite Loaded Substrate Integrated Waveguide (FLSIW) phase shifter is proposed. It is based on the non-reciprocal properties of an SIW line loaded with a single ferrite slab on one sidewall where the magnetic field strengths are highest. With the application of an external magnetic bias on the ferrite slab, the propagation constant of the FLSIW is tuned, thereby modifying the phase of the FLSIW section. An X-band non-reciprocal tunable phase shifter prototype is demonstrated. It achieves an insertion loss of better than 2 dB, a return loss of better than 10 dB and allows a phase shifting of 400° at 0.24 T of externally applied magnetic field. As an application of the non-reciprocal phase shifter, an isolator is designed and fabricated, which offers an isolation of 20 dB at 12.5 GHz.