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This article describes a new set of tools developed to improve the conception and modeling of nonsaturated ferrite-based devices such as twin toroid phase shifters. These new simulation tools benefit from a generalized permeability tensor model able to describe the permeability tensor of a ferrite sample whatever its magnetization state. This model is coupled to a homemade 3D multi-scale magnetostatic analysis program, which describes the evolution of the magnetization through the definition of a hysteresis loop in every mesh cell. These computed spectra are then integrated into 3D electromagnetic simulation software that retains the spatial variations of the ferrite properties by using freshly developed macro programming functions. This new approach allows the designers to accurately model complex ferrite devices such as twin toroid phase shifters. In particular, we demonstrated a good agreement between simulated and measured phase shifts as a function of applied current values with a predicted maximum phase shift of 0.96 times the measured value. [ABSTRACT FROM AUTHOR]

A numerical procedure to predict vibration and acoustic noise due to electromagnetic excitation forces in an axial flux motor (AFM) is presented and applied to a motor with ferrite magnets for electric vehicles. The methodology includes the calculation of radial magnetic forces exerted on stator inner surfaces using electromagnetic solver to account for vibration and noise of the motor. Fundamental and high-order harmonics of the magnetic forces are then obtained via fast Fourier transform process. Structural analyses such as modal and harmonic analysis are conducted to investigate natural resonant frequencies of the motor system and modal shapes highly responsible for vibration of the frame and acoustic noise. Magnitudes of vibration displacement on the motor housing surface and sound pressure level at a given point in the space are predicted using harmonic and acoustic analyses, respectively. Motor performance tests were conducted to validate the model, and the results showed that the model predictions agree well with the observations from the experiments. [ABSTRACT FROM PUBLISHER]

Switch mode power supplies are the predominant form through which power conversion is currently implemented in electronic equipment. Within such power supplies, ferrite cored magnetic components are commonly placed under dc bias conditions which, due to magnetomechanical effects, can result in higher than expected core losses. This paper presents measurements that show the impact of magnetomechanical effects on the losses of a MnZn ferrite core material under low ac excitation and high dc bias conditions. The measurements are made using an accurate measurement circuit, and the results show the impact on losses of magnetomechanical resonance. In addition distorted, figure-eight shaped B-H loops are measured, which are also believed to manifest from magnetomechanical interactions. These B-H loops show that, on a transient basis, magnetomechanical interactions may take place in a manner that is not only lossless, but returns energy back to the excitation supply. [ABSTRACT FROM AUTHOR]

This paper introduces the use of Viscous Plastic Processing (VPP) for the production of microwave ferrite materials and components. Conventional ceramic processing methods produce bulk ferrite materials restricted to relatively simple shapes and that can possess significant micro-structural defects resulting in poor mechanical properties. Using VPP the microstructures and physical strength of ferrite materials can be substantially enhanced and entirely new and unique device geometries produced, such as those based on ferrite helices. Ferrite Materials produced by VPP, such as lithium based ferrites, will be compared to those produced by standard methods of production such as powder pressing. [ABSTRACT FROM AUTHOR]

In this paper, a nonreciprocal left-handed transmission line has been investigated. It is composed of a normally magnetised ferrite microstripline periodically loaded with lumped capacitances and inductive stubs. Based on the simple equivalent circuit model for a predominant edge guided mode, the dispersion relation of the ferrite left-handed transmission line has been estimated, providing the backward wave characteristic in the positive and negative permeability frequency regions. With the aid of the finite element method, it is confirmed that specific three-dimensional structures do show left-handed characteristics as well as the nonreciprocity. Nonreciprocal transmission characteristics with the isolation of more than 30 dB are obtained numerically and demonstrated experimentally in the positive and negative permeability frequency regions, for the edge guided modes. It is explained that the nonreciprocity of the ferrite left-handed transmission line is caused by the leaky wave phenomenon from the microstrip to the ferrite substrate. [ABSTRACT FROM AUTHOR]

We investigated the complementary effects of TiO2 and MoO3 additives on the magnetic properties, the core loss, and the dielectric properties of MnZn ferrites. We analyzed the composition factors influencing the penneability of MnZn ferrites. A high initial penneability base ZnO-MnO-Fe2 O3 composition ratio was selected. Electrical and dielectric analyses indicated that the introduction of TiO2 can improve the high-frequency loss properties of MnZn ferrite cores, but such introduction will also have a negative effect on the magnetic properties of the sintered sampies. Introduction of MoO3 can alleviate the negative influence of TiO2 and also reduce the internal polarization intensity. As a result, the dielectric constant and corresponding dielectric loss may be reduced. We give experimental results in the paper. [ABSTRACT FROM AUTHOR]

We investigated the complementary effects of TiO2 and MoO3 additives on the magnetic properties, the core loss, and the dielectric properties of MnZn ferrites. We analyzed the composition factors influencing the penneability of MnZn ferrites. A high initial penneability base ZnO-MnO-Fe2 O3 composition ratio was selected. Electrical and dielectric analyses indicated that the introduction of TiO2 can improve the high-frequency loss properties of MnZn ferrite cores, but such introduction will also have a negative effect on the magnetic properties of the sintered sampies. Introduction of MoO3 can alleviate the negative influence of TiO2 and also reduce the internal polarization intensity. As a result, the dielectric constant and corresponding dielectric loss may be reduced. We give experimental results in the paper. [ABSTRACT FROM AUTHOR]

recently, various microwave absorbers have been studied and developed for electromagnetic interference problems. One of the important materials for absorbers is ferrite in which the high-frequency magnetization mechanism consists of a superposition of the motion of the magnetic wall and the rotation of the magnetization. Its complex permeability has a frequency dispersion; therefore, it is difficult to develop a rigorous theoretical analysis as a absorber. if a numerical analysis based on a simulation model is possible, the design of the absorber will be expedited. in the paper, the spatial network method is used for treating the hysteresis characteristics of the shift of the magnetic domain wall and the relaxation characteristics with an absorbing characteristic for the rotation of magnetization. A basic equivalent circuit model is proposed in which both are combined, and then this model is used to analyze the frequency characteristics of the reflection coefficient of a plane wave. The results based only on the basic relaxation model are shown to agree well with the theory. The basic validity of the model is verified by showing that the reflection coefficient is reduced at less than the matching frequency due to the hysteresis loss, and the matching frequency and the tendency agree with the experimental results by Ishino et al. [ABSTRACT FROM AUTHOR]

Microwave devices comprising magnetized ferrite in contact with superconductor circuits designed to eliminate magnetic field penetration of the superconductor have demonstrated phase shift without significant conduction losses. The device structures are adaptable to low- or high-T/sub c/ superconductors. A nonoptimized design of a ferrite phase shifter that employs niobium or YBCO meanderlines has produced over 1000 degrees of differential phase shift with a figure of merit exceeding 1000 degrees/dB at X band. By combining superconductor meanderline sections with alternating T junctions on a ferrite substrate in a configuration with three-fold symmetry, a low-loss three-port switching circulator has been demonstrated. [ABSTRACT FROM AUTHOR]

Two types of magnetic tape were produced by oblique sputtering with the incident angle of 65±5°. One consists of a 180-nm Cr underlayer layer and 20-nm Co layer. The other consists of a 90-nm NIAI seed layer, 90-nm Cr intermediate layer, and 20-nm Co layer. It is shown that the use of NiAI seed layer allows further reduction of the Co grain size and improves the film smoothness. The fine microstructure obtained in the NiAl seed layer resulted in smaller Co grains with more uniform size distribution. This caused the switching field distribution to become narrower, while the values of the squareness and coercivity remained high. The recording performances were also improved for the tape with N1Al seed layer. [ABSTRACT FROM AUTHOR]

Presents a phase-adjusted technique of the digital-latching ferrite phase shifter. Use of the perturbation approach; Voltage standing-wave ratio; Insertion loss.