Tunable isolator using a coupled microstrip line with an obliquely magnetised YIG substrate

A tunable isolator using a symmetrically coupled microstrip line is proposed. The even and odd mode dispersion characteristics of the symmetrically coupled microstrip line printed on a YIG substrate are obtained using a full wave spectral domain approach. The nonreciprocal coupling between the two-microstrip lines on a ferrite substrate can be exploited to achieve an isolation behaviour. The tunability is obtained by varying the applied angle of the DC bias magnetic field at the YIG substrate. Hence, a frequency tunable isolator is designed for use at the microwave frequency band.