A three-step unconditionally stable locally one-dimensional finite-difference time-domain method is proposed to represent an arbitrarily magnetized lossy ferrite medium. The small loss in the saturated ferrite is introduced to the algorithm through a simple explicit relation. A step-by-step procedure is established to minimize the number of operations and variables. It is shown that the processing time and occupied memory variables in the proposed method are about 90% and 50% of those of the one-step leapfrog alternating direction implicit method, respectively. The accuracy and stability of the method are verified through the simulation of wave propagation in two ferrite-loaded devices, including a microstrip phase shifter, and a stripline circulator.
