Ferrite Resonator Research Articles

Synthesis and characterization of (Ba2Zn2Fe12O22)1−x(NiFe2O4)x ferrite composites for antenna applications

A series of (Ba2Zn2Fe12O22)1−x(NiFe2O4)x ferrites (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were successfully synthesized by one-pot coprecipitation route. XRD analysis reveals the formation of Ba2Zn2Fe12O22 and NiFe2O4 composite after sintering calcined precursor powder at 1200 °C/4 h. Densification behaviour was evaluated by Archimedes’ principle. Field emission scanning electron microscopy was used to study morphological characteristics. Room temperature magnetization behaviour was evaluated using a vibrating sample magnetometer. In composite, it was observed that the saturation magnetization (Ms) and coercivity (Hc) increased with increasing NiF content. With the increase of NiF in the composite, the permittivity (ε) decreased from 28.6 (for x = 0.2) to 13.6 (for x = 0.8) with the corresponding decrease in dielectric loss (tanδε) at 100 MHz. The permeability (μ) also decreased from 21.3 (x = 0.2) to 17.9 (x = 0.8) with the associated decrease of the magnetic losses (tanδμ) at 100 MHz. Miniaturization factor (n) of 19.2 and characteristic impedance of 1.1 were obtained for x = 0.4 composition at 100 MHz along with low dielectric loss factor (tan δε/ε) and magnetic loss factor (tan δµ/µ). The ferrite resonator antenna was fabricated using FR4 as substrate and ferrite pellet as magneto-dielectric resonator material. The antenna characteristics parameters reflection loss S (1,1) and voltage standing wave ratio (VSWR) were measured by vector network analyser (VNA).

Breaking the limitation of terahertz resonances in ferrites through 4D printing of metamaterials

4D printing allows the creation of 3D-printed structures with a variety of new functionalities that respond to external stimuli, including electromagnetic properties, for which research is limited, such as terahertz resonances in ferrite materials; and therefore holding great promise for a wide range of applications. However, the limited physical properties of ferrite materials, including their anisotropic properties and limited material manipulation space, pose significant challenges to the development of ferrite materials designed for progressively increasing terahertz frequencies. Therefore, this paper proposes a platform for overcoming the limitations of terahertz resonance in ferrites through the 4D printing of metamaterials. Both the elastic and viscous moduli of the slurry are sensitive to the applied shear stress; as this stress increases, these moduli sharply decrease by several orders of magnitude, resulting in the transformation of the slurry into a fluid state similar to the liquefaction of ink. Electromagnetic coupling modes between electric dipoles and magnetic dipoles endow these ferrite metamaterials with induction and switching of terahertz resonances due to orientation stimulation. Our work sheds light on the creation of electromagnetic properties and their control by 4D printing.

Electric field tuning of a nickel zinc ferrite resonator by non-linear magnetoelectric effects

The nature of nonlinear magnetoelectric (NLME) effect has been investigated at room-temperature in a single-crystal Zn substituted nickel ferrite. Tuning of the frequency of magnetostatic surface wave (MSSW) modes under an applied pulsed DC electric field/current has been utilized to probe the effect. The frequencies of the modes at 8–20 GHz were found to decrease by ~ 400 MHz for an applied DC power P of ~ 100 mW and the frequency shift was the same for all of the MSSW modes and linearly proportional to P. A model is proposed for the effect and the NLME phenomenon was interpreted in terms of a reduction in the saturation magnetization due to the DC current. The decrease of magnetization with applied electric power, estimated from data on mode frequency versus P, was − 2.50 G/mW. The frequency tuning efficiency of the MSSW modes due to NLME effects in the ferrite resonator was found to be 4.1 MHz/mW which is an order of magnitude higher than the shift reported for M-type strontium and barium hexaferrite resonators investigated earlier. The spinel ferrite resonator discussed here has the potential for miniature, electric field tunable, planar microwave devices for the 8–20 GHz frequency range.

Evaluation of MnFe2O4-SiO2 composite dielectric resonator synthesized from in natura ores

We present the evaluation of a ferrite resonator antenna designed from MnFe2O4-SiO2 composite. The composite was synthesized from in natura ores, extracted in the state of Rio Grande do Norte, by solid state reaction. Two pellets were manufactured using 370 MPa and 740 MPa. Dielectric characterizations were performed previously, and new results are presented. Pressure increment led to a growth in MnFe2O4 phase, from 88.7% to 90.1%, and a decrease in ferrite and cristobalite crystallite size. Dielectric constant presented well-defined behavior close to 5.0 and agreement with morphological characteristics. Ferrite resonator was simulated according to the dielectric characterizations and magnetic properties estimative. TM110 theoretical results are presented and compared with the presented resonator. Reflection coefficient measurements are presented and compared to simulations. The error achieved in resonance frequency was lower than 0.15%, simulated radiation patterns presented low cross-polarization, below −55.33 dB. Simulated directivity, gain and efficiency are presented and discussed.

Y-type hexagonal ferrite-based band-pass filter with dual magnetic and electric field tunability

This work is on the design, fabrication and characterization of a hexagonal ferrite band-pass filter that can be tuned either with a magnetic field or an electric field. The filter operation is based on a straight-edge Y-type hexagonal ferrite resonator symmetrically coupled to the input and output microstrip transmission lines. The Zn2Yfilter demonstrated magnetic field tunability in the 8–12 GHz frequency range by applying an in-plane bias magnetic field H0 provided by a built-in permanent magnet. The insertion loss and 3 dB bandwidth within this band were 8.6 ± 0.4 dB and 350 ± 40 MHz, respectively. The electric field E tunability of the pass-band of the device was facilitated by the nonlinear magnetoelectric effect (NLME) in the ferrite. The E-tuning of the center frequency of the filter by (1150 ± 90) MHz was obtained for an input DC electric power of 200 mW. With efforts directed at a significant reduction in the insertion loss, the compact and power efficient magnetic and electric field tunable Zn2Y band-pass filter has the potential for use in novel reconfigurable RF/microwave devices and communication systems.

A Low-Profile, Electrically Small Ferrite Core-Loaded Grounded Split Ring Resonator Antenna for Military VHF/UHF Communication

A Low-Profile, Electrically Small Ferrite Core-Loaded Grounded Split Ring Resonator Antenna for Military VHF/UHF Communication

MgFe1.98O4 – BaFe12O19 magneto-dielectric composites based ferrite resonator antenna for super-high frequency applications

The structural, morphological, and wideband electromagnetic response of ( 1-x) MgFe 1.98 O 4 + x BaFe 12 O 19 composites with x = 20, 40, 60, and 80 wt percent (wt%) were investigated. The composites' sintering temperature was optimised to be 1250 °C for 2 h. The phase purity and independent existence of the end members in the composites were verified using XRD, Raman and FTIR spectroscopy. The microstructures of the sintered composites indicate the effect of grain growth on the density and grain packing efficiency. The relative permittivity of the composites is in the 9–11 range, while the relative permeability is between 1.4 and 2.8. The increase in BaFe 12 O 19 concentration from 20 to 80 wt% resulted in a dilution effect in permeability and enhanced saturation magnetization and coercive field strength. The composites with 20–80 wt% BaFe 12 O 19 possess a characteristic impedance ranging from 0.55 to 0.38 and a miniaturisation factor ranging from 5.16 to 3.82 at 900 MHz. The composites containing 20 and 40 wt% BaFe 12 O 19 exhibited appreciable miniaturisation factors of 5.16 and 5.24, respectively, with characteristic impedances of 0.55 and 0.47. Furthermore, these composites have low magnetic and dielectric losses of the order of 10 −1 and 10 −3 , respectively, making them suitable candidates for resonator antenna applications. A magneto-dielectric resonator antenna using the composite comprising 40 wt% BaFe 12 O 19 , with a density greater than 95%, was designed, simulated and fabricated. The fabricated magneto-dielectric resonator antenna resonated at a frequency of 14.7 GHz, with a significantly low return loss of −44 dB and wide impedance bandwidth of 1.44 GHz, suggesting the application potential of the dual-ferrite composite in the Ku-band frequency range.

Whispering-Gallery-Mode Microwave Sensing Platform for Oil Quality Control Applications

A growing demand has been established over the recent years for quick and inexpensive oil adulteration detection testing to convoy the automated and computerized processes in the industry. This research study presents a practical application of a simple low-resource microwave sensor of small size and high sensitivity to rapidly identify oil types, and monitor its quality and authenticity without having to open any bottles off-shelf. The sensor utilizes the nonreciprocal whispering-gallery-modes (WGMs) traveling on a ferrite ring resonator (FRR) when coupled to a microstrip line (MTL). The magnetic anisotropy of the ferrite is exploited to acquire four sensitive WGM resonances of nonreciprocal nature in the 22–32-GHz spectrum. A fabricated prototype is practically tested for identifying oil samples of different ingredients and brands, when loaded onto the FRR at consistent volume inside glass bottles of identical geometry. The measured scattering responses have shown a high detection sensitivity for the small contrast between the edible oils as demonstrated by the explicit frequency shifts in magnitude and phase of both S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> and S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> . The article also discusses a generalized concept for the complementing system layers in an Internet of Things (IoT) architecture for potential implementation in the industry.

Ferromagnetic Resonance-Enhanced Electrically Small Antennas

It is proposed that ferromagnetic resonance (FMR) of thin-film ferrites can be utilized to simultaneously improve the radiation efficiency and input impedance matching of electrically small antennas (ESAs). To validate the concept, the role of FMR in radiation is first derived analytically with an ideal thin-film ferrite radiator. It was concluded that the Gilbert damping of the ferrite, determining the quality factor of FMR, directly impacts on the radiation efficiency of the antenna. A practical example is proposed in the form of an electrically small single-loop antenna loaded with a thin-film yttrium-iron-garnet (YIG) core. The prototype has been designed, fabricated, and evaluated through both full-wave simulations and experiments. The simulation results match well to the experimental results, demonstrating the efficacy and significance of the idea. In addition, broadband equivalent circuit models are derived to model both the electrically small loops with and without the FMR enhancement and to provide additional insights into the design. The circuit models prove to be effective in predicting the input impedance and radiation efficiency of FMR-enhanced ESAs at a precision comparable with full-wave simulations.

Quadrupole resonator mode versus dipole one in photonic crystal ferrite circulators

We propose a photonic crystal circulator based on quadrupole resonance of a magnetized ferrite cylinder. This device consists of a T-junction composed by three waveguides in a two-dimensional photonic crystal with square lattice. The ferrite cylinder is placed in the center of the T-junction. The scattering matrix, analytical model and the numerically calculated frequency characteristics of the circulator for the central frequency 94.5 GHz are presented. This device is compared with the previously suggested T-type circulator based on the dipole resonance mode. In particular, we show that the use of the quadrupole resonance permits to reduce the necessary DC magnetic field in comparison with dipole mode case by six times and this is important at THz frequencies where the necessary field is excessively high. Besides, quadrupole resonance requires the higher diameter of the ferrite resonator. The ferrite cylinders are produced by a special technology, and higher dimensions lead to a better reproducibility of such elements. However, these advantages are achieved at the expense of higher insertion losses and lower bandwidth of the circulator.

Surface Electromagnetic Wave-Based Wireless Communication System for Mines

The paper discusses the advantages and shortcomings of resonance and single-frequency single-wire induction communication systems for mines. The issues of creating a magnetic induction communication system based on the twin transmission line (the MIKON-Tel queuing system) and the prospects for using small antennas to arrange two-way communication channels through the rock have been considered. The possibility of creating a multichannel queuing system for subscribers, which operates in a wide frequency band using a twin induction transmission line and small ferrite resonator antennas, is shown. The antenna designs used for magnetic induction communication in mines have been considered. High level of radio frequency signals has experimentally been proven when using a twin line and small antennas. The specific signal attenuation along the route in the coal mine was 4 dB/km. The results obtained prove the fundamental possibility of designing multichannel induction communication systems with a guaranteed communication range of over 4 km from the base station.

Design and analysis of nickel ferrite resonator antenna for C band applications

AbstractThis article shows the design of dielectric resonator antenna with nickel ferrite as dielectric material. Its main characteristics and measurements are described. Nickel ferrite was synthetized by sol–gel modified by ionic coordination reaction technique. Calcination was performed at 1100°C (10 h, 10°C/min step), followed by compression procedure at 227 MPa, to manufacture the bulk. Sintering process was applied at calcination temperature, for 4 h, to ensure bulk's physical resistance, and its electrical characterization was performed for antenna design and simulations. Simulated radiation patterns are presented, as reflection coefficient, which is compared with measurements. Measured reflection coefficient presented good agreement with performed simulations, with a difference of 0.74% in resonance frequency. Simulated radiation patterns also presented good results, with relatively high gain in co‐polarization planes, 2.11 dB for E plane, and low cross‐polarization E plane value, −47 dB.

Microstrip Ferrite Circulator Design With Control of Magnetization Distribution

This article presents a study of the impact of different external magnetic bias field (MBF) distributions on Y-junction microstrip ferrite circulator performance. By using magnetostatic, full-wave, and circuit commercial simulation tools for a circular ferrite disk, several permanent magnet (PM) configurations are investigated for unsaturated and nonuniform bias conditions. Eigenmode simulations are used to analyze the circulator bandwidth over a range of MBF intensities. We show in simulations and experiments that different bias conditions can result in an operating frequency range from 1.5 to 7GHz using the same 9.7-mm-diameter commercial ferrite disk resonator.

A magnetoactive metamaterial based on a structured ferrite

Subject and Purpose. The use of spatially structured ferromagnets is promising for designing materials with unique predetermined electromagnetic properties welcome to the development of magnetically controlled microwave and optical devices. The paper addresses the electromagnetic properties of structured ferrite samples of a different shape (spatial geometry) and is devoted to their research by the method of electron spin resonance (ESR). Methods and methodology. The research into magnetic properties of structured ferrite samples was performed by the ESR method. The measurements of transmission coefficient spectra were carried out inside a rectangular waveguide with an external magnetic field applied. Results. We have experimentally shown that over a range of external magnetic field strengths, the frequency of the ferromagnetic resonance (FMR) of grooved ferrite samples (groove type spatial geometry) increases with the groove depth. The FMR frequency depends also on the groove orientation relative to the long side of the sample. We have shown that as the external static magnetic field approaches the saturation field of the ferrite, the FMR frequency dependence on the external static magnetic field demonstrates "jump-like" behavior. And as the magnetic field exceeds the ferrite saturation field, the FMR frequency dependence on the groove depth gets a monotonic character and rises with the further growth of the field strength. Conclusion. We have shown that the use of structured ferrites as microwave electronics components becomes reasonable at magnetic field strengths exceeding the saturation field of the ferrite. At these fields, such a ferrite offers a monotonically increasing dependence of the resonant frequency on the external magnetic field and on the depth of grooves on the ferrite surface. Structured ferrites are promising in the microwave range as components of controlled filters, polarizers, anisotropic ferrite resonators since they can provide predetermined effective permeability and anisotropy

Nickel ferrite powder resonator antenna capsuled by low permittivity wood materials

AbstractThis article presents the synthesizing of nickel ferrite by sol‐gel modified ionic coordination reaction technique with application in millimetric wave Ferrite Powder Resonator Antenna device fed by a coaxial probe. The ferrite powder was morphologically characterized by X‐rays diffraction, energy dispersive X‐Ray spectrometer, and scanning electron microscopic image; hysteresis loop was also obtained to analyze static magnetic field application and powder's electrical characterization was performed. Ferrite powder electric characterization displayed consistent data, including a material resonance phenomenon around 7.4 GHz. The ferrite powder resonator antenna was designed according to IEEE 802.11a/n protocol and, at resonance frequency around 2.8 GHz, the reflection coefficient results presented a noninfluence of wood material in antenna response, along with a good agreement between experimental and simulated results, reaching a maximum relative error of 1.82%, indicating a promising application of ferrite powder as a resonator.

Calculation and experimental measurement of the spectra of natural vibrations of ferrite resonators of nonreciprocal waveguide devices microwave and EHF

In the proposed work, in the approximation of magnetic walls, an equation is obtained for determining the natural frequencies of the resonator, which can be used in the design of both E- and H-planar devices. The main laws of the spectra of natural vibrations of ferrite resonators and their influence on the electrodynamic parameters of nonreciprocal devices are revealed. Experimental results for E- and H-plane circulators are presented and discussed. The optimal procedure for configuring nonreciprocal ferrite devices is described.

Analysis of the probing field in magneto-dipolar-mode microwave microscopy

Abstract The research of chiral materials in microwaves is attractive in a lot of physical disciplines. Compared to the field of optics, where many theoretical and measurements analysis tools and techniques exist, in microwaves, the study is at its initial stages of development. Recently, microwave devices based on a ferrite disk resonator with magneto-dipolar-mode (MDM) oscillations that allow creation of near fields characterized by helical structure have been developed. These near fields, called magneto-electric (ME) fields, are essential for the chirality characterization of the sample. For effective focusing of the ME fields a special microwave device based on a metallic wire positioned above a ferrite disk was developed. Such a device allows to narrow down the effective area of the ME fields by more than an order. In this work, we show a theoretical analysis of the localized ME fields generated by a metallic wire on a ferrite disk operating as the microwave microscope. Realization of such localized ME fields is an important step in the development of a microwave sensor for effective sensing of natural and artificial enantiomeric materials.

Method for Computing Frequency Response and Radiation Pattern of Magnetized Cylindrical Ferrite Resonator Antenna

This paper presents a theoretical model of a cylindrical ferrite resonator (FR) antenna that predicts resonance frequencies, the frequency tuning range, and radiation patterns. The FR antenna is placed on a PEC ground plane and is excited by a coaxial probe with a dc magnetic bias field applied in the direction transverse to the ground plane. An open-boundary model to predict the resonance frequency is introduced and compared with the measured results. The all-boundary model is in good agreement with the measured results compared with the other models. The discrepancy of the proposed model is less than 3%. The ${\text {HE}}_{11\delta }$ mode-splitting behavior caused by the tensor nature of the permeability of a biased ferrite is investigated. It is shown that the frequency and polarization of the antenna are tunable. The operating frequency can be chosen in the range from 8.54 to 10.115 GHz. In addition, the linear polarization is radiated at no bias, while the circular polarization is radiated at the magnetized case. The results of the theory correspond approximately with the measured and simulated results for radiation patterns.

A Multiscale Unconditionally Stable Time-Domain (MUST) Solver Unifying Electrodynamics and Micromagnetics

A rigorous yet computationally efficient 3-D numerical method has been proposed based on modified alternatingdirection-implicit finite-difference time-domain (ADI FDTD) methods. It has the capability of modeling the anisotropic and dispersive properties of magnetic material. The proposed algorithm solves Maxwell's equations and Landau-Lifshitz-Gilbert equation jointly and simultaneously, requiring only tridiagonal matrix inversion as in ADI FDTD. The accuracy of the modeling has been validated by: 1) the nonreciprocity of an X-band ferrite resonance isolator; 2) the attenuation constant of a magnetically tunable waveguide filter; and 3) the dispersive permeability of a 2-μm-thick magnetic thin film. Time steps that are up to 5000 times larger than the Courant-Friedrichs-Lewy limit have been used in these simulations without encountering stability issues. The simulation results agree with the predictions made from the theory, the commercial software or the experiments. Moreover, the algorithm has been applied to predict the effect of high permeability thin films in platform effect reduction. An electric current sheet close to a perfect electrically conducting plane coated with a 2-μm-thick magnetic thin film is simulated, which exhibits an enhanced surface resistance by three orders of magnitude higher than that without the magnetic thin film.

Cavity magnon polaritons with lithium ferrite and three-dimensional microwave resonators at millikelvin temperatures

Single crystal lithium ferrite (LiFe) spheres of sub-mm dimension are examined at mK temperatures, microwave frequencies, and variable dc magnetic field, for use in hybrid quantum systems and condensed matter and fundamental physics experiments. Strong coupling regimes of the photon-magnon interaction (cavity magnon polariton quasiparticles) were observed with coupling strength of up to 250 MHz at 9.5 GHz (2.6%) with magnon linewidths of order 4 MHz (with potential improvement to sub-MHz values). We show that the photon-magnon coupling can be significantly improved and exceed that of the widely used yttrium iron garnet crystal, due to the small unit cell of LiFe, allowing twice the spins per unit volume. Magnon mode softening was observed at low dc fields and, combined with the normal Zeeman effect, creates magnon spin-wave modes that are insensitive to first-order magnetic-field fluctuations. This effect is observed in the Kittel mode at 5.5 GHz (and another higher order mode at 6.5 GHz) with a dc magnetic field close to 0.19 tesla. We show that if the cavity is tuned close to this frequency, the magnon polariton particles exhibit an enhanced range of strong coupling and insensitivity to magnetic field fluctuations with both first-order and second-order insensitivity to magnetic field as a function of frequency (double magic point clock transition), which could potentially be exploited in cavity QED experiments.