Accurate modeling of nonreciprocal microwave devices based on magnetic opal nanocomposites

A numerical technique for the accurate modeling of nonreciprocal microwave devices (MDs) based on magnetic nanocomposites by using rigorous mathematical models to solve the 3D diffraction boundary problems is developed. The models are based on the solution of Maxwell´s equations with electrodynamic boundary conditions complemented by the Landau-Lifshitz equation with the exchange term. Using the decomposition algorithm based on the projection method by autonomous blocks with magnetic nanoinclusions and virtual Floquet channels (MFABs) the elements of multimode multi-channel scattering matrix of magnetic opal nanocomposite-based circulators were calculated at microwave frequencies. The waveguide transmission and reflection measurements of scattering parameters of the circulators based on magnetic opals were performed at frequencies from 14 GHz to 38 GHz. The numerical technique shows an excellent agreement with experimental data. It is shown that the magnetic opal nanocomposite-based circulators have improved performances: bigger isolation, smaller insertion losses and a wider pass band as compared to ferrite-based MDs.