Electromagnetic Filter Research Articles

ЕКСПЕРИМЕНТАЛЬНІ ДОСЛІДЖЕННЯ ПАРАМЕТРІВ ЕЛЕКТРОМАГНІТНИХ ФІЛЬТРІВ

Наведені результати досліджень з розподілу індукції магнітного поля у циліндричному корпусі, заповненому феромагнітною загрузкою, вздовж висоти корпусу при різних діаметрах корпусів. На основі принципу суперпозиції магнітних полів і графічних залежностей встановлено відстані між осердям суміжних електромагнітів при різних діаметрах корпусів. На основі досліджень запропоновано конструкцію електромагнітного фільтра з використанням тангенціальних електромагнітів, розміщених по відношенню до корпусу з загрузкою у взаємно перпендикулярних площинах. Запропоноване технічне рішення дозволяє створити по висоті корпусу у феромагнітній загрузці однакові умови для ефективного осадження магнітних домішок.

Effects of graphene on light transmission spectra in Dodecanacci photonic quasicrystals

We make a theoretical study of light waves, for both TE and TM polarization with oblique incidence. The light waves propagate on SiO2/TiO2 multilayers, organized by Dodecanacci sequence, where we consider a graphene monolayer at the interfaces between distinct layers. We also calculate numerically the optical transmissivity spectrum, by using the transfer matrix method, for the cases with a graphene sheet and without a graphene sheet at the interfaces. Our results indicate that the whole optical spectrum becomes affected by the presence of graphene in the interfaces. Among these effects, we can highlight the shift of bandgaps to high-frequency regions, the emergence of a graphene induced bandgap at low-frequency regions, and the decreasing of transmittance in the whole frequency range considered here. The self-similarity, which is a property that indicates a fractal spectrum, keeps essentially unchanged when we consider graphene sheets between the layers. Our studies can be applied to electromagnetic filters, where an input gate voltage, applied on the graphene sheets, can control the bandgaps which arise on these structures.

Investigation and Modeling of Combined Feedforward and Feedback Control Schemes to Improve the Performance of Differential Mode Active EMI Filters in AC–DC Power Converters

In this paper, the models of active differential mode electromagnetic interference input filters for ac–dc converters are first investigated. The models are developed for active filters with single feedback (FB) and single feedforward (FF) configurations, which include an active filter, passive filters, and the noise model for a converter. To increase the gain of the single active filter, the models for FB–FF, FF–FB, parallel FB, and series feedback (SFB) configurations are developed and investigated. Loop gains and insertion gains for all of these configurations are derived and compared. Stability has been analyzed based on the loop gains and a compensation technique is introduced to ensure stability. Based on the comparison among all these control configurations, it has been found that the SFB configuration can achieve the highest noise reduction. The loop gains and insertion gains of an active filter prototype with the SFB configuration are measured using a network analyzer to validate the developed model and compensation technique. Finally, spectrum measurements with a commercial boost power factor correction ac–dc converter have been conducted to verify the developed modeling and control techniques as well as the predicted performance for the SFB configuration.

P$^{3}$DCT—Partial-Power Pre-Regulated DC Transformer

In this paper, a new approach to regulate the output voltage of a resonant, constant voltage transfer ratio 380 V/48 V isolated dc–dc converter is presented. Rather than applying variable frequency control to the resonant converter, which would result in reactive power processing and a more complicated electromagnetic compatibility filter design, the converter remains in its optimal operating point all time and an additional partial-power (PP) processing auxiliary converter is used to tightly regulate the output voltage. The PP converter, supplied through a tertiary winding of the resonant converter's transformer, regulates the output by adding or subtracting voltage from the dc input and has only a marginal impact on the overall efficiency of the dc–dc converter. The principal of operation is explained in detail including Sankey diagrams to illustrate the power processing of the converter and a feedback control system is proposed to tightly regulate the 48 V output voltage. A hardware demonstrator rated at 1.5 kW is implemented to cope with input voltage variations between 340 and 420 V and experimental results are provided showing that the output voltage can be kept within $\pm {1}{\%}$ of the nominal 48 V even under harsh input voltage and load transients. The realized dc–dc converter with PP pre-regulation features an overall efficiency of 97.7 $\%$ at rated power and a power density of 8.6 kWdm $^{-3}$ (141w/ $^{3}$ in).

Periodic Metallo-Dielectric Structures: Electromagnetic Absorption and its Related Developed Temperatures.

Multi-layer, metallo-dielectric structures (screens) have long been employed as electromagnetic band filters, either in transmission or in reflection modes. Here we study the radiation energy not transmitted or reflected by these structures (trapped radiation, which is denoted—absorption). The trapped radiation leads to hot surfaces. In these bi-layer screens, the top (front) screen is made of metallic hole-array and the bottom (back) screen is made of metallic disk-array. The gap between them is filled with an array of dielectric spheres. The spheres are embedded in a dielectric host material, which is made of either a heat-insulating (air, polyimide) or heat-conducting (MgO) layer. Electromagnetic intensity trapping of 97% is obtained when a 0.15 micron gap is filled with MgO and Si spheres, which are treated as pure dielectrics (namely, with no added absorption loss). Envisioned applications are anti-fogging surfaces, electromagnetic shields, and energy harvesting structures.

Paper-based metasurface: Turning waste-paper into a solution for electromagnetic pollution

Paper-based electronics offer a simple and cost-effective means to fabricate flexible devices. Here, we report an efficient pen-on-paper approach to construct metasurfaces on paper with silver units. Further, paper-based metasurfaces are employed to shield the electromagnetic interference which create new opportunities in turning waste paper into a solution for eliminating electromagnetic pollution. Experimental measurements and simulations show that waste paper-based metasurface manufactured in this way exhibits remarkable electromagnetic shielding properties with small thickness (thickness reduced more than 90% compared with that of traditional shielding materials), which makes it an ideal candidate for specific frequency electromagnetic filters. In addition, it can be readily extended to other regions of the electromagnetic spectrum, widened the shielding band by simply scaling the silver units' sizes and utilizing appropriate three-dimensional structures. Having taken performance into consideration, production is also taken into account. Paper-based shields offer both economic and energy benefits when considered on electronic printing, in addition, environment friendly nature and pliability of paper as well as simple fabrication procedure make paper-based metasurfaces promising candidates for the future ‘green’ electronics.

A New Method for Dimensioning and Designing the Zero-Sequence Electromagnetic Filter Considering System Displacement Power Factor

This paper proposes an innovative method for dimensioning and designing the zero-sequence electromagnetic filter applied to three-phase four-wire distribution power systems. As premises, the optimum ratio between zero-sequence and positive-sequence impedances of the filter must be established in order to potentiate the filtering percentage of zero-sequence currents and ensure the quality of the supply system displacement power factor. The calculations are based on the sequential harmonic transmittances of the equivalent circuit reduced to the coupling point of the electromagnetic filter. To validate the proposed method, the results obtained with the application of the electromagnetic filter designed in a test system using the MATLAB software are compared to the results of the system modeled in the PSIM software.

The increasing of H−current from Penning ion source with electrically biased metal hydride cathode

The possibility of the current increasing of negative hydrogen ions H− extracted in the longitudinal direction from gas-feed-free Penning type ion source with metal hydride cathode by the electric cathodes bias has been investigated. The separation of negative ions from the extracted flux of charged particles was performed by an electromagnetic filter, which consists of a magnetic coil for electron diverting and a grid under positive potential for positive ion reflection. The optimum for the effective extraction of H− ions has been determined. The H− ion current of 10 μA was obtained at an input power of 6 W.

Rapid and high-performance processing technology for large-area frequency selective surfaces

Frequency selective surfaces (FSSs) with periodic smart structures have widespread applications in many areas, especially in electromagnetic wave filters. In this paper, a rapid and high-performance processing technology for large-area FSSs was presented. This novel technology combined laser direct writing lithography (LDWL) with wet chemical etching (WCE) (i.e., LDWL + WCE). Basing on experiments and in the condition of optimal parameters (i.e., 40 mW laser power, 1000 mm/s scan speed, single scan, 20 μm hatch space, pattern-profile scan path, and ferric chloride aqueous solution as etchant) of LDWL + WCE, a large-area (200 × 200 mm2) aperture type FSS with 625 square-loop units was fabricated within 8 min on a FR-4 copper-clad plate (with 12 μm-thickness copper layer). When the same FSS was prepared by commonly-used laser direct ablation (LDA) technology with itself optimal processing parameters, it needed about 62 min (nearly 8 times as much time as the former). Scanning electron microscopy (SEM) and surface probe profilometry analyses showed that the edges of the square-loop patterns fabricated by LDWL + WCE were steeper and smoother, and the FR-4 substrate had no damage. In an anechoic chamber, the electromagnetic wave filtering performances of the as-prepared FSSs were tested, and the results indicated that the FSS fabricated by LDWL + WCE had a bandpass response at 7.08 GHz with a transmittance of 97.75%. Its frequency response curve was in better agreement with the simulation result. The technology of LDWL + WCE also has the potential to rapidly fabricate large-area and/or non-planar FSSs with high performance.

Notice of Retraction: Multiple Objectives Optimization for an EBG Common Mode Filter by Using an Artificial Neural Network

One of the recent frontiers of the multiple objectives optimization strategies is the introduction of an artificial neural network in place of a more time-consuming numerical tool or approach to compute the cost functions. This paper describes the development of a multiple objectives optimization strategy for an electromagnetic bandgap common mode filter by using an artificial neural network. The network training, that is to say the evaluation of the internal weights and biases, is optimized by a genetic algorithm. The results are discussed and also compared with those stemming from an already developed multiple objective sequential optimization strategy applied to the same common mode filter. In both strategies, the cost functions are the same and the optimization algorithm is a differential evolutionary one.

Adjoint Technique for Sensitivity Analysis of Coupling Factors According to Geometric Variations

A physical interpretable equivalent electrical network and its parameters are extracted from a 3-D finite-element model formulated by Darwin’s approximation to the Maxwell equations. In this paper, we add a sensitivity analysis procedure to the extraction of inductive parasitics, relying upon the adjoint technique for the extracted partial inductances and coupling factors. The resulting algorithm is an efficient way to calculate the sensitivities with respect to a large number of parameters. In an example, we use the gradient information to guide the geometrical optimization of an electromagnetic compatibility filter.

Controllable frequency and polarization THz filter based on graphene fish‐scale metamaterial

AbstractIn this work, we propose and numerically analyze a new electromagnetic polarization filter in THz region based on graphene fish‐scale structure. The array is composed by graphene strips placed on a metallized dielectric substrate. The filter can operate in two different frequency regions that can be shifted in frequency by appropriate choice of width of the graphene ribbons. We present as an example, at f1 = 0.483 THz, the structure possesses the reflection coefficient of −0.38 dB for the incident waves with x‐polarization and −48.05dB for the y‐polarized ones, while at f2 = 0.792 THz, the reflection coefficients are −47.25 dB for x‐polarization and −0.86 dB for y‐polarization. The physics of the device is based on surface plasmon polariton (SPP) resonances in the graphene. The central frequency can be dynamically adjusted by changing the chemical potential (ie, by an external voltage for example) of the graphene strips.

Effect of metal-hydride hydrogen activation on longitudinal yield of negative ions from PIG

We present the results of the study of activated hydrogen, desorbed from a metal hydride cathode, effect on a PIG ability to emit negative hydrogen ions H− in the longitudinal direction. It becomes possible due to a change in the discharge properties with the further output of negatively charged particles together with positive ions along the magnetic field. The separation of negative ions from an extracted flow of charged particles was carried out by an electromagnetic filter. The efficiency of the filter was investigated and the optimal external parameters for H− ions separation were determined. The beam current of H− ions has been obtained at the level of 5 mkA at an average discharge current 2 mA and a discharge voltage 5 kV.

The dependence of the structure and mechanical properties of thin ta-C coatings deposited using electromagnetic venetian blind plasma filter on their thickness

In this paper, we present the results of studies determining the optimum thickness of amorphous tetrahedral carbon (ta-C) thin films for industrial applications. ta-C coatings from 50 to 1000nm thickness were synthesized by a pulsed vacuum-arc method using a water-cooled electromagnetic Venetian blind plasma filter. Systematic studies of the thickness dependence of the microstructure and mechanical properties showed that the content of sp3 bonds in all the deposited coatings are equal (about 68%), but the 300nm thick coatings exhibited the best mechanical properties (hardness H>50GPa, adhesion Lc2=48N). These coatings were deposited on industrial cutting taps with 2 and 2.5mm diameters and tested in industrial conditions. The results of the threading tests performed with Inox stainless steel showed that the durability of the ta-C coated tools were significantly higher compared with the uncoated ones. These real-world industrial tests confirmed the usefulness of the electromagnetic Venetian blind plasma filter for synthesizing thin ta-C coatings with excellent physico-mechanical characteristics.

Studi Penurunan Kadar Logam Besi (Fe) dan Logam Mangan (Mn) pada Lempung terhadap Perubahan Arus Listrik dalam Solenoida

In the soil there are many compound of Fe and Mn as well as in the clay. Those two compounds need to be reduced to improve the resistive value of the clay. One method to reduce those compounds is by electromagnetic filter using solenoid. From the experiment circuit, it was found that the resistive value was 4.5 Ohm with maximum current of 5 Ampere. Concentration of Fe and Mn after filtered were 0.46 ppm and 0.40 ppm respectively.

A laser-assisted process to produce patterned growth of vertically aligned nanowire arrays for monolithic microwave integrated devices

An experimental process for the fabrication of microwave devices made of nanowire arrays embedded in a dielectric template is presented. A pulse laser process is used to produce a patterned surface mask on alumina templates, defining precisely the wire growing areas during electroplating. This technique makes it possible to finely position multiple nanowire arrays in the template, as well as produce large areas and complex structures, combining transmission line sections with various nanowire heights. The efficiency of this process is demonstrated through the realisation of a microstrip electromagnetic band-gap filter and a substrate-integrated waveguide.

Ferromagnetic Nanorods in Applications to Control of the In‐Plane Anisotropy of Composite Films and for In Situ Characterization of the Film Rheology

Ferromagnetic nanorods play important roles as active fillers in multifunctional composite films. Many composite films used as inductors and antennae, as recording media, or electromagnetic (EM) filters and polarizers, require the nanorod alignment in a certain direction. The strategy for the in‐plane alignment of nanorods has not been established yet. Since the composite assumes a multistep processing when the material rheological properties change in time, in situ characterization of the film is required. Magnetic rotational spectroscopy (MRS) with ferromagnetic nanorods offers flexibility and accuracy providing desired spatial and temporal resolution in characterization of submicron thick films. Herein, recent progress in understanding of the basic physical principles is presented guiding the nanorod alignment in thin films by external magnetic field and characterization of these films by MRS.

Miniaturized dielectric waveguide filters

ABSTRACTDesign techniques for a new class of integrated monolithic high-permittivity ceramic waveguide filters are presented. These filters enable a size reduction of 50% compared to air-filled transverse electromagnetic filters with the same unloaded Q-factor. Designs for Chebyshev and asymmetric generalised Chebyshev filter and a diplexer are presented with experimental results for an 1800 MHz Chebyshev filter and a 1700 MHz generalised Chebyshev filter showing excellent agreement with theory.

FPGA-based self-organizing fuzzy controller for electromagnetic filter

Electromagnetic filters (EMF) are used to clean magnetic particles in industrial liquids which play important roles to sustain the high-quality material production in industrial fields. In this study, an FPGA-based adaptive fuzzy controller is realized to sustain high performance of an EMF. An experiment is performed by using realized adaptive controller on an EMF set. The results obtained from the experiment are compared with the results of the conventional fuzzy controller. It is observed that adaptive fuzzy controller is performed better than the conventional fuzzy controller.

Removal of Iron Oxide With Superconducting Magnet High Gradient Magnetic Separation From Feed-Water in Thermal Plant

By the accident of Fukushima Daiichi Nuclear Plant, all the nuclear plants have stopped in Japan. As a result, the operation rate of thermal power plants has been increased. It caused growth in CO 2 emission, which requires some kind of countermeasure. We focused on the iron oxide scales deposited on the piping system and boiler which declines the heat exchange efficiency of thermal power plants. In this study we attempt to remove the iron scales from the piping system and the boiler to maintain the power generation efficiency. In the current thermal plant treated by All Volatile Treatment (AVT) the iron elutes to the feed water in the low-temperature part which changes into iron ion or the paramagnetic fine iron oxide particles. On the other hand at the high-temperature part the main component of the scales is large ferromagnetic particles of magnetite. Therefore the magnetic separation at the high-temperature part is the more effective to remove the scale than that at the low-temperature part. For the reason, the existing method using the electromagnetic filter placed in the low-temperature part is not effective to remove the scales. We studied the high gradient magnetic separation (HGMS) at high-temperature part to remove a large amount of the scale. In this study, we assumed to install the HGMS system using the superconducting magnet at the inlet of the boiler.