scholarly journals Frequency dispersion model of the complex permeability of soft ferrites in the microwave frequency range

Author(s):  
Antonio Barba‐Juan ◽  
Andrés Mormeneo‐Segarra ◽  
Nuria Vicente ◽  
Juan Carlos Jarque ◽  
Carolina Clausell‐Terol
2011 ◽  
Vol 2011 (CICMT) ◽  
pp. 000224-000231
Author(s):  
Nelu Blaž ◽  
Andrea Marić ◽  
Goran Radosavljević ◽  
Nebojša Mitrović ◽  
Ibrahim Atassi ◽  
...  

Complex magnetic permeability and hysteresis characteristic are key parameters that determine properties of ferrite components. This paper offers effective, accurate and simple method for complex permeability determination of LTCC (Low Temperature Co-fired Ceramic) ferrite sample at wide frequency range (up to 1 GHz). Presented research can be found to be of importance in fields of ferrite components design and application, as well as RF and microwave engineering. The characterization sample is a stack of LTCC tapes forming a toroidal shape structure. Commercially available ferrite tape ESL 40012 was used and standard LTCC processing applied for the sample fabrication. Permeability is determined in the frequency range from 10 kHz to 1 GHz and characterization procedure is divided in two segments - for low and high frequencies. Low frequency measurements (from 10 kHz to 1000 kHz) are performed using LCZ meter and discrete turns of wire, while a short coaxial sample holder and Vector Network Analyzer were used for the higher frequency range (from 1000 kHz to 1 GHz). Hysteresis properties of this material are also determined. B-H hysteresis loops were measured with BROCKHAUS Tester MPG 100D system using the maximum excitation of 2 kA/m and frequencies of 50 Hz, 500 Hz and 1000 Hz. In addition, we presented another important factor in the practical design, the temperature variation of the permeability dispersion parameters. Obtained results show good agreement with datasheet values given by the manufacturer at lower frequencies and are in good correlation with results extracted from developed dispersion model at higher frequencies.


2019 ◽  
Vol 28 (7) ◽  
pp. 451-461
Author(s):  
Habib Khouni ◽  
Nacerdine Bouzit

The principal subject of the present article is the study of the phenomenon of dispersion as well as the effect of the concentration of strontium titanate (SrTiO3) and carbon black on the complex permittivity of ternary composites: epoxy resin–SrTiO3 –black carbon. The relative permittivity of the mixtures as a function of volume fraction of SrTiO3 was modeled by the modified Lichtenecker mixing law (MLL). A new dispersion model, based on the Lorentzian resonance model, has been proposed to describe the frequency behavior of complex permittivity. For these ternary composites, the frequency dispersion behavior of the complex permittivity that exhibits both relaxation and resonance spectra with increasing SrTiO3 concentration has been showed. The new empirical equation proposed in our work has been well describing the complex permittivity of resonance type for the SrTiO3 and carbon black composites. The effects of SrTiO3 content on the electromagnetic properties and absorption characteristics of electromagnetic waves of epoxy resin composites were studied. As the volume fraction of SrTiO3 increases, it was confirmed that the complex permittivity of the composites follows the MLL and the resonant frequency shifted toward the high frequency range. The resonance frequency of the composites was estimated in good agreement with the theoretical values calculated by the second new equation proposed in this article. Complex permittivity is measured using time domain spectroscopy in the frequency range direct current (DC) to 30 GHz.


Author(s):  
Hyung Do Choi ◽  
Kyoung Sik Moon ◽  
In Soo Jeon ◽  
Wang Sup Kim ◽  
Tak Jin Moon

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 125
Author(s):  
Yuqi Jin ◽  
Yurii Zubov ◽  
Teng Yang ◽  
Tae-Youl Choi ◽  
Arkadii Krokhin ◽  
...  

An acoustic metamaterial superlattice is used for the spatial and spectral deconvolution of a broadband acoustic pulse into narrowband signals with different central frequencies. The operating frequency range is located on the second transmission band of the superlattice. The decomposition of the broadband pulse was achieved by the frequency-dependent refraction angle in the superlattice. The refracted angle within the acoustic superlattice was larger at higher operating frequency and verified by numerical calculated and experimental mapped sound fields between the layers. The spatial dispersion and the spectral decomposition of a broadband pulse were studied using lateral position-dependent frequency spectra experimentally with and without the superlattice structure along the direction of the propagating acoustic wave. In the absence of the superlattice, the acoustic propagation was influenced by the usual divergence of the beam, and the frequency spectrum was unaffected. The decomposition of the broadband wave in the superlattice’s presence was measured by two-dimensional spatial mapping of the acoustic spectra along the superlattice’s in-plane direction to characterize the propagation of the beam through the crystal. About 80% of the frequency range of the second transmission band showed exceptional performance on decomposition.


2004 ◽  
Vol 42 (5) ◽  
pp. 383-385 ◽  
Author(s):  
Asier Ibáñez Loinaz ◽  
Carlos del Río Bocio

Geophysics ◽  
1984 ◽  
Vol 49 (9) ◽  
pp. 1556-1557
Author(s):  
Heikki Soininen

The authors discussed the behavior of the resistivity spectra by means of the Cole‐Cole dispersion model. They also discussed the corrections with which the petrophysical resistivity spectrum can be reduced into an apparent resistivity spectrum caused by a polarizable body embedded in an unpolarizable environment. The application of the Cole‐Cole dispersion model is a marked step forward in spectral IP analysis. However, closer attention must be paid to the assumptions and approaches on which the authors base the relations between the petrophysical and apparent spectra. The authors based their relations between the true and apparent spectra on the use of the dilution factor [Formula: see text]. In accordance with the definition by Seigel (1959), they assumed that [Formula: see text] is a real constant (independent of frequency) over the whole frequency range under consideration. First consider the justification for the assumption of the existence of a constant factor [Formula: see text] in the light of an example calculated for phase spectra. Similar considerations could also be made with the aid of amplitude spectra.


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