On the properties of microstrip directional couplers on magnetized ferrimagnetic layers

The aim of this work is to present a study of microstrip directional couplers on magnetized ferrites. The external dc magnetic field is assumed to be oriented in the y direction and its magnitude can be varied, allowing a magnetic control of the coupler properties. The Hertz vector potentials, oriented along the ferrite magnetization direction, are used to obtain the dyadic Green´s function in an impedance matrix form. The numerical solution is based on Galerkin´s method applied in the Fourier transform domain. Results are included as a function of structural parameters and of biasing magnetic field.