Analysis of microstrip circulator with a ferrite sphere

A novel microstrip circulator with a magnetized ferrite sphere is proposed for millimeter wave communications. A three-dimensional finite-difference time-domain (FDTD) approach for the analysis of this ferrite sphere based microstrip circulator is presented. The electromagnetic fields inside the ferrite junction are calculated using special updating equations derived from the equation of motion of the magnetization vector and Maxwell´s curl equations in consistency. Frequency dependent insertion loss, isolation and reflection loss of the circulator are calculated over a wide band of frequencies with a single FDTD run. Experimental results at Ka band are presented and compared with theoretical simulation. As a result, a good agreement is found between them.