Electromagnetic Filter Research Articles

Anderson localization of circularly polarized waves in a gyrotropic superlattice with correlated disorder

In this paper, we explore the transmission of circularly polarized electromagnetic waves through one-dimensional random periodic-on-average photonic crystals containing layers of magneto-optical material in Faraday geometry. Driven by evidence that long-range correlations crucially influence wave localization within certain spectral ranges, our study aims to harness these effects for the development of novel electromagnetic wave filters tunable via a dc magnetic field. We base our study on a model of light propagation through a finite array of alternating dielectric layers with random thickness variations and layers of gyrotropic material of equal thickness. Assuming weak positional disorder, we employ analytical and numerical methods to analyze the inverse localization length and assess filter performance. Our results demonstrate that specific correlated disorder introduced into periodic systems can enhance or suppress the transmissivity for a wave of a given frequency in any desired interval of the magneto-optical parameter q. Additionally, we show that the Anderson localization can be resonantly suppressed when the thickness of each gyrotropic layer accommodates an integer number of half-wavelengths.

Three-dimensional quantum Hall states as a chiral electromagnetic filter

Three-dimensional quantum Hall states as a chiral electromagnetic filter

Ultra-wideband terahertz absorber with switchable multiple modes based on graphene and vanadium dioxide metamaterials

This article proposes a dynamic switchable broadband absorber based on graphene and vanadium dioxide (VO2). The temperature could adjust the conductivity of VO2, and external voltage could alter the conductivity of graphene. Therefore, they can be used for broadband absorption that can be switched between low and high frequencies and for achieving coupled ultra-wideband absorption. When the Fermi level of graphene is 0.9eV and VO2 is in a non-metallic state, the absorber can achieve absorption of over 90% in the range of 2.55THz-4.86THz. When the Fermi level of graphene is 0.1eV and VO2 is in a metallic state, the absorber can achieve absorption of over 90% in the range of 4.30THz-9.40THz. When the Fermi level of graphene is 0.6eV and VO2 is in a metallic state, the absorber can achieve absorption of over 90% in the range of 2.32THz-9.80THz. The absorber only partially depends on the incident angle of the incident light, simulation results show that when the incident angle is below 50 degrees, more than 90% of the absorption bandwidth changes less. The absorber has no relation to the polarization angle of the incident light, and can keep its original property at any polarization angle. This structure has potential applications in electromagnetic wave stealth devices, optical switches and filters.

Smart Transfer Planer with Multiple Antenna Arrays to Enhance Low Earth Orbit Satellite Communication Ground Links

In this study, we propose a smart transfer planer equipped with multiple antenna arrays to improve ground links for low Earth orbit (LEO) satellite communication. The STP features a symmetrical structure and is strategically placed on both ends of a window, serving both indoor and outdoor environments. Using the window glass as a medium, energy transmission occurs through a coupling mechanism between the planers. The design focuses on large array antenna design, beamforming networks, and coupler design on both sides of the glass. Beamforming networks enable the indoor and outdoor antenna arrays to switch beams in various directions, optimizing high-gain antennas with narrow beamwidths. Through electromagnetic induction and filter couplers, a robust signal transmission channel is established between indoor and outdoor environments. This setup significantly enhances communication efficiency, particularly in non-line-of-sight environments.

High attenuation electromagnetic interface filter for effective processing of audio signals

Suppressing the noise or unwanted signal from the raw signal makes the system work efficiently. Electromagnetic interface (EMI) can cause the system/device to lose the data, damage the electronic equipment, interrupt the audio, or video signals, lead to poor reception, etc EMI filters are used in telecommunications, military equipment, satellite communication, etc At the industry level, EMI filters are used for home appliances, medical equipment, motor controls, test equipment, etc In this paper, active and passive EMI filters are designed to avoid or attenuate EMI or noise (unwanted EMI signal) and implemented on Xilinx Nexys 4 Artix 7 FPGA board. The filters provide a significant improvement in the attenuation of the EMI. MATLAB tool is used to design the filters, which are highly immune to undesired signals, give better stability, and perform over a wide range of frequencies. Depending on the filters’ coefficients, the frequency response will be changed. Phase response and amplitude response of the EMI filters are calculated. Insertion loss of the active filter is 1.5836, and for the passive filter, 1.9382. The gain of active and passive filters is 0.7359 and 0.912 respectively. The return loss of the active and passive EMI filters is 20 dB. HDL code is generated using MATLAB for the implementation of filter on FPGA. Using MATLAB HDL coder for implementing is new and it simplifies the design, as a result development time is reduced. Xilinx Vivado tool is used for the implementation of active filter. The total on-chip power is 0.146 W. Dynamic power is 0.049 W, and device static power is 0.097 W. The utilization of LUTs and slice registers are less, compared to the previous filter implementation, which leads to reduce the cost of hardware implementation.

Exact Synthesis of Hybrid Acoustic–Electromagnetic Filters With Wideband Chebyshev Responses

Exact Synthesis of Hybrid Acoustic–Electromagnetic Filters With Wideband Chebyshev Responses

A Systematic Methodology for Parasitic Capacitance Estimation and Validation of Multichip Modules

This paper proposes a method for extracting parasitic capacitances from die terminals to baseplate in a multi-chip-module (MCM). The parasitic capacitors constitute the common mode (CM) equivalent circuit model enabling filter design. While traditionally simple open module die area measurements are used to calculate capacitance from concerned nodes to baseplate, such methods result in breaking the module or contamination, rendering the module useless. This is especially concerning for high voltage (HV) rated modules (> 10 kV) where cost can be a deciding factor. Hence, a non-intrusive double pulse test method is developed to extract the parasitic capacitance from specific nodes to ground without physical damage to the module. Consequently, the proposed method is verified using a series of tests and open module measurements. The distributed capacitors can be transformed into lumped capacitors for electromagnetic compatibility (EMC) simulations and filter design. The proposed method is analyzed on a Three-Level Neutral Point Clamped (3L-NPC) phase leg module and compared against traditional method. Finally, the impact of estimation errors on the proposed method are discussed.

Some Procedures in Mitigating Conducted Electromagnetic Interference

In our opinion, the problem of conducted interference generated by power converters, represents not a simply mater of harmonics or even interharmonics, as usually is considered, but really a broader issue, which requires a careful treatment of a continuous spectrum of frequency, extending until 30MHZ. The following paper presents a conducted electromagnetic interference problem in the case of a power converter, included in one kinetic therapy equipment (actually a treadmill). Analysis is made, considering only conducted emissions at the mains supply port of the equipment. Tests carried out, outlined a few procedures in the analysis and mitigation of electromagnetic conducted interferences using electromagnetic interference mains filters. Virtually all products contain a power supply filter as the last circuit that noise currents pass through before they exit the product through the power cord. Sometimes, properly designed transformers can provide inherent filtering, and so can obviate the need for an intentional filter. In other cases, like the one presented in the paper, mains filters are not enough for mitigating conducted interferences and they must be replaced, or simpler retrofitted by an additional one, the filters’ cascade being able more often to mitigate perturbations. Mains passive EMI filters carry potentially high currents at dangerously high voltages, so the choice of these filters is an essential issue. From the paper it can be seen that the EMI filter issues should be considered with careful attention by designers, because they are not only ancillary devices, as they are more often treated.

Systematic pole-zero sorting method for neuro-TF modeling of electromagnetic response.

Neuro-transfer functions (neuro-TF) modeling method has been developed as one of the popular methods for parametric modeling of electromagnetic (EM) filter responses. The discontinuity issue of zero and pole data caused by extraction using vector fitting w.r.t. geometrical parameters change affects the neuro-TF training process and limits its modeling accuracy. This issue is addressed by this paper which proposes a novel systematic pole-zero sorting method for neuro-TF parametric modeling. The proposed method can obtain continuous pole-zero data which change much more smooth w.r.t. geometrical parameters change than the existing neuro-TF method, especially solves the difficulty of disorder of positive and negative values due to small values. The proposed systematic sorting method can substantially improve the modeling accuracy during the establishment and training of neuro-TF model over the existing neuro-TF method without systematic sorting.

Morphology dependent negative dielectric permittivity in spinel ferrite nanostructures

Metamaterials with negative dielectric permittivity has become a research hotspot due to their potential efficacy in various electromagnetic utilizations, such as, filter and antenna design, novel capacitance and inductor design, electromagnetic absorber etc. This study unfurls immense possibilities of inducing metamaterial properties such as negative dielectric permittivity in Magnesium Ferrite, a naturally occurring compound, just by restructuring the morphology. Herein, we report the correlation between structural, dielectric, and magnetic properties of the system in the same chemical composition but different morphologies, namely, nano solid spheres (NSSs) and nano hollow spheres (NHSs). Strikingly, only NHSs show negative dielectric permittivity owing to the Lorentz dielectric resonance in the vicinity of a metamagnetic transition. Further investigations show that the hollow cores and greater number of interfaces in NHSs, in comparison to NSSs, cause the uncompensated charges to accumulate within them and release at some frequencies and temperatures, leading to the backscattering of dipoles, which in turn induces the resonance. NSSs with stronger anti-ferromagnetic interaction and impermeable morphology do not show any sign of negative dielectric permittivity.

Magneto-Mechanical Metamaterials: A Perspective

Abstract Magneto-mechanical metamaterials possess unique and tunable properties by adjusting their shape configurations in response to an external magnetic field. Their designs and functionalities are diverse and are utilized in a wide variety of applications, such as highly tunable elastic and electromagnetic wave filters and targeted shape morphing. In this perspective, we examine the general background of magneto-mechanical metamaterials and their diverse applications. The possible future directions in the field are also thoroughly discussed.

A Proposed Frequency Selective Surface (FSS) using Bio-Inspired Element for Wi-Fi 6E Applications

Recently bio-inspired elements with shapes or geometries found in nature have received special attention, both for applications in antennas and in electromagnetic filters, the unit cell of the proposed FSS consists of a modification in a bio-inspired shaped element. A single and multilayered band-stop Frequency Selective Surface (FSS), with polarization independence, is proposed to be used in frequency applications at 6.0 GHz (Wi-Fi 6E). In the industry, Wi-Fi 6E is the name that identifies those Wi-Fi devices that operate in the 6.0 GHz band, designed to improve efficiency and more capacity than previous standards. Band-stop frequency responses for the single and multilayer structures are presented. The simulated frequency responses show bandwidth values for inhibit transmission about of 1.75 GHz and 3.15 GHz, respectively for single and multilayer structures. Furthermore, good agreement between simulated and measured results is shown for the single bio-inspired FSS. The proposed FSS structure presents features that allow its use as an electromagnetic filter or its integration with microstrip antennas developed for applications in the same standard.

Metamaterial inspired electromagnetic bandgap filter for ultra-wide stopband screening devices of electromagnetic interference

Presented here is a reactively loaded microstrip transmission line that exhibit an ultra-wide bandgap. The reactive loading is periodically distributed along the transmission line, which is electromagnetically coupled. The reactive load consists of a circular shaped patch which is converted to a metamaterial structure by embedded on it two concentric slit-rings. The patch is connected to the ground plane with a via-hole. The resulting structure exhibits electromagnetic bandgap (EBG) properties. The size and gap between the slit-rings dictate the magnitude of the reactive loading. The structure was first theoretically modelled to gain insight of the characterizing parameters. The equivalent circuit was verified using a full-wave 3D electromagnetic (EM) solver. The measured results show the proposed EBG structure has a highly sharp 3-dB skirt and a very wide bandgap, which is substantially larger than any EBG structure reported to date. The bandgap rejection of the single EBG unit-cell is better than − 30 dB, and the five element EBG unit-cell is better than − 90 dB. The innovation can be used in various applications such as biomedical applications that are requiring sharp roll-off rates and high stopband rejection thus enabling efficient use of the EM spectrum. This can reduce guard band and thereby increase the channel capacity of wireless systems.

Experimental study of electromagnetic disturbances in common and differential modes in a circuit based on two DC/DC boost static converter in parallel

Introduction. An electronic control and closing control at the switch (MOSFET) will allow a parallel connection of two DC/DC boost converters. The reason for paralleling converters is to increase the efficiency of the power conversion process. This means that the overall power loss on the main switches is half the power loss on the main switch of a converter. It has been proven that DC-DC converters operating in parallel have different dynamics than a single converter. In this paper, the study is based on a system of two boost converters operating in parallel under current mode control. Although two converters operating in parallel increase the efficiency of the system, if the control parameters are not chosen correctly, the system becomes unstable and starts to oscillate. Purpose of this work is to present the analysis of high frequency electromagnetic disturbances caused by the switching of power switches in DC/DC boost static converters mounted in parallel in the presence of cables. We will study the improvement of the electromagnetic compatibility performances which can be brought by the choice of a static converters for industrial use. Methods. For the study of the path of the currents in common mode and in differential mode, it was possible to evaluate experimentally the electromagnetic compatibility impact in common mode and in differential mode of two boost converters connected in parallel in an electric circuit in connection with the source through a printed circuit board of connection between the source and the load, while using the two basic methods, namely the prediction of the conducted electromagnetic interference, the temporal simulation and the frequency simulation. Results. All the obtained results are validated by experimental measurements carried out at the Djillali Liabes University Sidi-Bel-Abbes in Laboratory of Applications of Plasma, Electrostatics and Electromagnetic Compatibility (APELEC). The experimental results obtained in common mode and in differential mode at low, medium and high frequencies are compared between the parallel boost test with and without electromagnetic compatibility filter.

MODULATION OF NEGATIVELY CHARGED PARTICLE FLUX FROM PENNING DISCHARGE WITH METAL HYDRIDE CATHODE

The features of modulation of negatively charged particle flux extracted along the magnetic field from Penning discharge with metal hydride cathode have been investigated. The separation of negative ions from coextracted electrons was performed by an electromagnetic filter with efficiency not worse than 90 %. It is shown that electrons in the extracted flow are deeply modulated with the frequency of the diocotron instability of the anode layer, while negative ions are not. An increase in the interelectrode distance and anode length resulted in a more pronounced expression of this effect due to the minimization of the influence of the magnetic field of the filter on the discharge.

Electromagnetic Filtering with High Performance by one Dimensional Defective Comb-Like Waveguides Structure Using the Transfer Matrix

In this paper, we study the propagation of electromagnetic waves in 1D photonic comb-like waveguides (CWGs) structure. This CWGs structure is constituted by a periodicity of segments of length d1 and grafted in each site by one resonator of length d2. This system creates the pass bands separated by large photonic band gaps where the electromagnetic waves cannot propagate. Our study focuses on the impact of a geometrical defect on the transmission spectrum. The creation of a defect of length d02 at the resonator in a perfect structure makes it possible to identify localized modes (defect modes) in the bandgaps. In this research, we demonstrate that a single defect at the resonator can lead to the filtering of two or more frequencies. The analytical calculation is performed using the transfer matrix method. This method aims to calculate the dispersion relation and the transmission rate. This structure has potential applications as an electromagnetic guiding, filtering and demultiplexing.

Система обеспечения параметров воздуха в помещении для содержания крупного рогатого скота

Creating comfortable conditions for animals ensures their longevity and high productivity. Artificial ventilation, which includes supply and exhaust systems and a control system, minimizes the influence of the human factor on maintaining the indoor air parameters. The proposed system of indoor air-conditioning for the loose cattle housing layout was developed based on the analysis of ventilation systems of livestock premises and studies proving the effectiveness of dehumidification in winter using a regenerative heat exchanger. The system for providing indoor air parameters was developed using the computer-aided design program “Compass” (CAD) of the “Askon” company. The developed system for providing indoor air parameters for keeping cattle includes an electrofilter and a coarse filter, fans, a plate heat exchanger, a turbodefector; temperature, humidity, and air flow velocity sensors, dust collectors, a pump, a tank with a disinfectant, and a mechanism for shutting down supply air and recirculated air. The use of a recuperative dehumidification system at low outdoor temperatures helps maintain the relative indoor humidity within the regulatory limits (75…40%) and reduce the concentration of carbon dioxide by 20…45%. To ensure these indoor air parameters without dehumidification, 200 kW of thermal power is needed to heat the supply air. The proposed combined energy-saving all-season climate control system provides monitoring of indoor air parameters and energy saving through the use of a turbo deflector, disinfects the ventilation air, dehumidifies the air in the cowshed in winter and cools in summer, and also partially removes dust from the air with an electromagnetic filter.

Dynamic algorithm for fitness function greatly improves the optimization efficiency of frequency selective surface for better design of radar

Multiple objectives optimization of frequency selective surface (FSS) structures is challenging in electromagnetic wave filter design. For example, one of the sub-objectives, the sidelobe level (SLL), is critical to directional anti-interference, which is complicated and becomes the bottleneck for radar design. Here, we established a dynamic algorithm for fitness function to automatically adjust the weights of multiple objectives in the optimization process of FSS structures. The dynamic algorithm could efficiently evaluate the achieving probability of sub-objectives according to the statistical analysis of the latest individual distribution so that the fitness function could automatically adjusted to focus on the sub-objective difficult to optimize, such as SLL. Computational results from the dynamic algorithm showed that the efficiency of multi-objective optimization was greatly improved by 213%, as compared to the fixed-weighted algorithm of the fitness function. Specifically for SLL, the efficiency rate increased even better, up to 315%. More interestingly, the FSS structures were most improved while picking median value or golden section value as the reference value. Taken together, the current study indicated that the dynamic algorithm with fitness function might be a better choice for FSS structural optimization with SLL suppression and potentially for the better design of lower SLL radar.

Modeling and Minimization of the Parasitic Capacitances of Single-Layer Toroidal Inductors

High-frequency power converters need electromagnetic interferences filters using common and differential mode chokes with low parasitic capacitance to comply with the electromagnetic compatibility standards. This article proposes a modeling method of this capacitance and ways to minimize it. The studied components are ring core inductors with magnetic materials considered as perfect conductors or with high permittivity, such as nanocrystalline material and most Mn-Zn ferrite materials. In comparison to other work in the literature, the proposed approach takes into account the curvature of the turn, in addition to the coating of the core and the insulation layer of the wire. The hypotheses, used in this article to simplify the real geometry, are compatible with two-dimensional (2-D) approaches to compute the parasitic interturns and turn–core capacitances. These capacitances are evaluated thanks to the 2-D finite element method. The obtained model allows accurate evaluation of the effect of turn–core space on the parasitic capacitance, and enables to reduce its value with a limited impact on the volume of the magnetic component.

Magnetically Actuated Reconfigurable Metamaterials as Conformal Electromagnetic Filters

Electromagnetic Filters In article number 2200106, Renee Zhao and co-workers report reconfigurable electromagnetic metamaterials based on magnetically responsive lattices. The magnetic actuation enables fast and programmable structural reconfigurations between flat deployed/folded and curved deployed/folded states for both conformal and freestanding metamaterials. The integrated customizable subwavelength patterns effectively switch the metamaterial between accepting and rejecting incident electromagnetic waves upon structural reconfiguration.