In this work, a compact finite-difference time-domain (FDTD) algorithm with a memory-reduced technique is proposed for the dispersion analysis of rectangular waveguides either fully or partially loaded with longitudinally-magnetized ferrite. In this algorithm, the divergence theorem is used to eliminate the longitudinal components of the electric and magnetic flux densities. The mobius transform (MT) technique is applied for the first time to obtain the equations relating the magnetic field to the magnetic flux density in a ferrite medium. Some examples are presented to validate the obtained algorithm with numerical results: good agreement is obtained with a significant reduction in the memory space requirement compared to the conventional algorithm.
In this paper, the constitutive relation of longitudinally magnetized ferrites (LMF) is simplified and transformed to an equivalent relation involving tensors with first-order dispersive components more suitable for use in the time domain analysis. Further treatment leads to a diagonal permeability tensor that yields approximating formulas to relate the magnetic field to the magnetic flux density, which allows eliminating this later and reducing the number of field variables involved. Later, a similar result is achieved using a variable transformation. This reveals that magnetized ferrites actually have a permeability tensor simpler than the Polder tensor, in addition to a permittivity tensor with first-order dispersive components, which contradicts the known theory about ferrites. Finally, it is shown that the results obtained for the LMF case could be extended to the transversely magnetized ferrite case and to the general case of arbitrary state of magnetization. Some examples are presented with numerical results to validate the proposed formulations.
Index Terms-Dispersion, finite-difference time domain (FDTD), gyromagnetic resonance, magnetized ferrites, Polder tensor.0018-9464
In the title paper, two efficient time-domain equations and new permeability and permittivity tensors with dispersive components were obtained for the analysis of magnetized ferrite. In this work, we will show that this is due to the use of a reference rotating around the axis of magnetization of magnetized ferrite with the resonance frequency, instead of the usual fixed reference.
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