Ferrite resonators for mm-wave range devices

2016 ◽  
Author(s):  
Петров ◽  
V. Petrov ◽  
Гаценко ◽  
A. Gatsenko
Keyword(s):  
Magnetic Anisotropy ◽  
Saturation Magnetization ◽  
Line Width ◽  
Communication Systems ◽  
Anisotropy Field ◽  
Hexagonal Structure ◽  
Microwave Devices ◽  
Starting Point ◽  
Wave Range ◽  
Frequency Selective

Currently on the way are R&D works targeted to expand operational frequencies of microwave devices, including frequency selective ones. The expansion occurs both at low and at high end of the frequency range. Due to the microwave communication systems trend of increasing transmitted data flow rate and volume, as well as for precise object resolution by the vision systems, one needs to shift microwave device operational frequencies to the mm-wave range. Operational frequencies of mm-wave range microwave devices are defined by crystallographic magnetic anisotropy field and magnetic activity of the ferrite material (4πМS/ΔH), related with saturation magnetization and ferromagnetic resonance (FMR) line width. For creation of mm-wave range frequency selective devices are needed the ferrite resonators made of materials with high crystallographic magnetic anisotropy field values, as well as high saturation magnetization and narrow FMR line width. R&D works undertaken in the institute show that such materials can be created on the basis of ferrites with hexagonal structure. As a starting point for the development of the material was taken barium hexaferrite with M-type structure (BaFe12O19). Single crystals with composition BaFe12-xAlxO19 and BaFe12-xScxO19 were received from a solution in melt. By this way one may create materials with anisotropy field values from 5 to 50 kÖe, saturation magnetization from 3900 to 4700 Gauss, narrow FMR line width, and Curie temperature from 370° to 445° С. The dependencies of crystallographic magnetic anisotropy field and saturation magnetization vs diamagnetic dilution and temperature are investigated, as well as FMR line width vs temperature, density and orientation of the growing grains.

The Effect of Introduced Defects on Saturation Magnetization and Magnetic Anisotropy Field of L1$ _{0}$ FePt

2011 ◽  
Vol 47 (10) ◽  
pp. 2422-2424 ◽  
Author(s):  
Lei Shen ◽  
Zhi-Min Yuan ◽  
Jing Qiang Goh ◽  
Tiejun Zhou ◽  
Bo Liu ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Saturation Magnetization ◽  
Anisotropy Field

scholarly journals Small-angle neutron scattering correlation functions of bulk magnetic materials

2015 ◽  
Vol 48 (5) ◽  
pp. 1437-1450 ◽  
Author(s):  
Denis Mettus ◽  
Andreas Michels
Keyword(s):  
Magnetic Field ◽  
Correlation Function ◽  
Magnetic Anisotropy ◽  
Neutron Scattering ◽  
Saturation Magnetization ◽  
Applied Magnetic Field ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Anisotropy Field ◽  
Two Dimensional

On the basis of the continuum theory of micromagnetics, the correlation function of the spin-misalignment small-angle neutron scattering cross section of bulk ferromagnets (e.g.elemental polycrystalline ferromagnets, soft and hard magnetic nanocomposites, nanoporous ferromagnets, or magnetic steels) is computed. For such materials, the spin disorder which is related to spatial variations in the saturation magnetization and magnetic anisotropy field results in strong spin-misalignment scattering dΣM/dΩ along the forward direction. When the applied magnetic field is perpendicular to the incoming neutron beam, the characteristics of dΣM/dΩ (e.g.the angular anisotropy on a two-dimensional detector or the asymptotic power-law exponent) are determined by the ratio of magnetic anisotropy field strengthHpto the jump ΔMin the saturation magnetization at internal interfaces. Here, the corresponding one- and two-dimensional real-space correlations are analyzed as a function of applied magnetic field, the ratioHp/ΔM, the single-particle form factor and the particle volume fraction. Finally, the theoretical results for the correlation function are compared with experimental data on nanocrystalline cobalt and nickel.

THE INCREASING OF DATA TRANSFER NOISE IMMUNITY IN DEPARTMENTAL COMMUNICATION SYSTEMS OF SHORT-WAVE RANGE

2018 ◽  
pp. 7-19
Author(s):  
B. G. Shadrin ◽  
◽  
D. E. Zachateyskiy ◽  
V. A. Dvoryanchikov Dvoryanchikov ◽  
◽  
...  
Keyword(s):  
Communication Systems ◽  
Noise Immunity ◽  
Data Transfer ◽  
Short Wave ◽  
Wave Range

scholarly journals Propagation Channel Measurements in the mm- and Sub-mm Wave Range for Different Indoor Communication Scenarios

2021 ◽  
Vol 42 (4) ◽  
pp. 357-370
Author(s):  
M. A. Salhi ◽  
T. Kleine-Ostmann ◽  
T. Schrader
Keyword(s):  
Wireless Communication ◽  
Communication Systems ◽  
Wireless Communication Systems ◽  
Electromagnetic Spectrum ◽  
Channel Measurements ◽  
Frequency Range ◽  
Propagation Channel ◽  
Data Rates ◽  
Indoor Wireless ◽  
Wave Range

AbstractIncreasing data rates in wireless communications are accompanied with the need for new unoccupied and unregulated bandwidth in the electromagnetic spectrum. Higher carrier frequencies in the lower THz frequency range might offer the solution for future indoor wireless communication systems with data rates of 100 Gbit/s and beyond that cannot be located elsewhere. In this review, we discuss propagation channel measurements in an extremely broad frequency range from 50 to 325 GHz in selected indoor communication scenarios including kiosk downloading, office room communication, living rooms, and typical industrial environments.

Effect of Thickness on Mechanically Tunable Magnetic Anisotropy of FeGa Thin Films Deposited on Flexible Substrates

2015 ◽  
Vol 815 ◽  
pp. 227-232 ◽  
Author(s):  
Ying Yu ◽  
Shu Hong Xie ◽  
Qing Feng Zhan
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Effective Strain ◽  
Anisotropy Field ◽  
Saturation Field ◽  
Effective Anisotropy ◽  
Magnetostriction Constant ◽  
The Difference ◽  
Different Strains

A practical way to manipulate the magnetic anisotropy of magnetostrictive FeGa thin films grown on flexible polyethylene terephthalate (PET) substrates is introduced in this study. The effect of film thickness on magnetic properties and magnetostriction constant of polycrystalline FeGa thin films was investigated. The anisotropy field Hk of flexible FeGa films, i.e., the saturation field determined by fitting the hysteresis curves measured along the hard axis, was enhanced with increasing the tensile strain applied along the easy axis of the thin films, but this enhancement via strain became unconspicuous with increasing the thickness of FeGa films. In order to study the magnetic sensitivity of thin films responding to the external stress, we applied different strains on these films and measure the corresponding anisotropy field. Moreover, the effective magnetostriction constant of FeGa films was calculated from the changes of both anisotropy field and external strain based on the Villari effect. A Neel’s phenomenological model was developed to illustrate that the effective anisotropy field of FeGa thin films was contributed from both the constant volume term and the inverse thickness dependent surface term. Therefore, the magnetic properties for the volume and surface of FeGa thin films were different, which has been verified in this work by using vibrating sample magnetometer (VSM) and magneto-optic Kerr effect (MOKE) system. The anisotropy field contributed by the surface of FeGa film and obtained by MOKE is smaller than that contributed by the film volume and measured by VSM. We ascribed the difference in Hk to the relaxation of the effective strain applied on the films with increasing the thickness of films.

VOLTAGE CONTROL OF MAGNETISM IN MULTIFERROIC HETEROSTRUCTURES AND DEVICES

SPIN ◽  
2012 ◽  
Vol 02 (03) ◽  
pp. 1240004 ◽  
Author(s):  
NIAN X. SUN ◽  
GOPALAN SRINIVASAN
Keyword(s):  
Magnetic Field ◽  
Communication Systems ◽  
Recent Progress ◽  
Phase Shifters ◽  
Ultra Wideband ◽  
Superior Performance ◽  
Microwave Devices ◽  
Multiferroic Materials ◽  
Multiferroic Heterostructures ◽  
Rf Microwave

Multiferroic materials and devices have attracted intensified recent interests due to the demonstrated strong magnetoelectric (ME) coupling in new multiferroic materials and devices with unique functionalities and superior performance characteristics. Strong ME coupling has been demonstrated in a variety of multiferroic heterostructures, including bulk magnetic on ferro/piezoelectric multiferroic heterostructures, magnetic film on ferro/piezoelectric slab multiferroic heterostructures, thin film multiferroic heterostructures, etc. Different multiferroic devices have been demonstrated, which include magnetic sensors, energy harvesters, and voltage tunable multiferroic RF/microwave devices which are compact, lightweight, and power efficient. In this progress report, we cover the most recent progress on multiferroic heterostructures and devices with a focus on voltage tunable multiferroic heterostructures and devices with strong converse ME coupling. Recent progress on magnetic-field tunable RF/microwave devices are also covered, including novel non-reciprocal tunable bandpass filters with ultra wideband isolation, compact, low loss and high power handling phase shifters, etc. These novel tunable multiferroic heterostructures and devices and tunable magnetic devices provide great opportunities for next generation reconfigurable RF/microwave communication systems and radars, Spintronics, magnetic field sensing, etc.

Mechanochemical Synthesis of Hexagonal Ferrites BaFe12O19

2018 ◽  
Vol 781 ◽  
pp. 119-124 ◽  
Author(s):  
Viktor Zhuravlev ◽  
Anna Nevmyvaka ◽  
Volya Itin ◽  
Dmitry Velikanov
Keyword(s):  
Phase Composition ◽  
Saturation Magnetization ◽  
Mechanochemical Synthesis ◽  
Annealing Temperature ◽  
Structural Parameters ◽  
Anisotropy Field ◽  
Magnetic Characteristics ◽  
Hexagonal Ferrites ◽  
Increasing Temperature ◽  
Synthesized Materials

The phase composition, structural parameters, and basic magnetic characteristics of BaFe12O19 hexaferrites prepared by the mechanochemical synthesis with subsequent annealing at a temperature of 1000°С and 1100°С for 1 h are investigated. The influence of the annealing temperature on the properties of synthesized materials is analyzed. Values of the saturation magnetization and the anisotropy field are determined. It is established that annealing temperature in the interval 1000 - 1100 °C does not significantly affect on the phase composition and the size of nanoparticles. The value of the anisotropy field increases substantially with increasing temperature.

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