Attenuation Of Electromagnetic Waves Research Articles

Mitigation of reentry blackout via gas injection in arc-heating facility

Communication blackouts during atmospheric reentry pose significant challenges to the safety and adaptability of spacecraft missions. This phenomenon, caused by the attenuation of electromagnetic waves by the plasma surrounding the spacecraft, disrupts communication with ground stations or orbiting satellites. Therefore, it is crucial to decrease the plasma density in the vicinity of the spacecraft to ensure an unobstructed electromagnetic wave communication path. This study proposes a methodology that involves the injection of gas from the vehicle’s wall to create an insulating layer near the surface. This thin layer maintains lower temperatures and reduced plasma density, enabling electromagnetic wave propagation without attenuation. Practical experiments were conducted in an arc-heating facility to simulate atmospheric reentry conditions. The results of the experiments provided empirical evidence of the effectiveness of the technique in mitigating communication blackout phenomena. Numerical fluid analysis within the wind tunnel chamber validated the formation of an air film layer near the experimental model owing to the injected gas. Schlieren imaging revealed distinctive jet shapes, which corroborated the findings of the numerical analysis. The wind tunnel tests that simulated atmospheric reentry environments confirmed the formation of an air film layer through gas injection, which substantiates the reduction in communication blackout. These results have the potential to improve communication reliability in space transport.

Molecular Intercalation‐Induced Two‐Phase Evolution Engineering of 1T and 2H‐MS2 (M = Mo, V, W) for Interface‐Polarization‐Enhanced Electromagnetic Absorbers

AbstractPolarization at interfaces is an important loss mechanism for electromagnetic wave (EMW) attenuation, though the motion behavior of carriers in interfaces composed of different types of conductors has yet to be investigated. Tuning the phase structure of transition metal dichalcogenides (TMDs) MS2 (M = Mo, V, W) by organics small molecule intercalation to achieve the modulation of interfacial types is an effective strategy, where 1T‐MS2 exhibits metallic properties and 2H‐MS2 has semiconducting properties. To exclude the contribution of the intrinsic properties of TMDs materials, three TMDs (MoS2, VS2, and WS2), which also possess phase transitions, are investigated. Among them, the 1T‐MS2 composite exhibits excellent EMW absorption performance under the synergistic effect of interfacial polarization and conduction loss. 1T‐MoS2/MOF‐A exhibits the best EMW absorption performance with an RLmin of −61.07 dB at a thickness of 3.0 mm and an EAB of 7.2 GHz at 2.3 mm. The effectiveness of the modulation of the interfacial polarization using 1T‐phase and 2H‐phase MS2 is demonstrated, which is important for the analysis of the carrier motion behavior during the interfacial loss.

MOFs-derived 3D flower-like Y2O3/C microspheres with efficient electromagnetic wave absorption properties

Y2O3 has emerged as a promising material for electromagnetic wave (EMW) absorption due to its excellent dielectric properties. However, the inherent insulating nature and single loss mechanism limit its absorption performance. Research on the microstructure modulation and component regulation of Y2O3-based absorbers remains relatively unexplored. In this work, Y2O3/C composites with flower-like architectures were synthesized for the first time via a metal-organic framework (MOFs) templating method. The effects of pyrolysis temperature on the microstructure, phase composition, and EMW absorption performance of the Y2O3/C composites were systematically investigated. At a pyrolysis temperature of 800 °C, the flower-like Y2O3/C microsphere exhibited optimal EMW absorption performance. The minimum reflection loss (RL) of pristine Y2O3 was only −4.75 dB, while the Y2O3/C composite achieved a minimum RL of −51.77 dB and a maximum effective absorption bandwidth of 4.32 GHz. Moreover, by simply adjusting the matching thickness, the optimal sample exhibited strong absorption (RL < −30 dB) over a wide frequency range of 4–18 GHz. The incorporation of carbon effectively neutralized the insulating nature of Y2O3, thereby optimizing the impedance matching. The synergistic effects of multiple loss mechanisms, including polarization loss, resistance loss, and interfacial polarization, facilitated substantial EMW attenuation. This study provides a promising strategy for the design and fabrication of high-performance rare-earth oxide EMW absorbers with tunable morphologies and properties.

Construction of ZIF/CS and ZIF/CS-derivatives with high-efficiency adsorption for dyes/antibiotics and strong microwave absorption performance

Bimetallic Zn/Co-ZIF was in situ loaded onto the surface of chitosan (CS) to form ZIF/CS composites with high-efficiency adsorption of antibiotics (tetracycline (TC)) and dyes (Congo Red (CR), Malachite Green(MG)). The particle size and surface roughness of Zn/Co-ZIF can be effectively adjusted by changing the mass ratio of Zn and Co in ZIF, which helps to regulate the adsorption active sites on the surface of the composites. Meanwhile, the introduction of CS changes the pore structure of the composites, making the molecules of TC, CR and MG easily enter into the pores of ZIF/CS. When the mass ratio of Zn to Co is 1:1, the ZIF/CS composite has the optimal adsorption performance with the ultra-high adsorption capacity qm of 781.3, 1644.2 and 3243.6mgg-1 for TC, CR and MG, respectively. Impressively, the ZIF/CS-derivative (ZC3-700) from sample ZC3 after calcination at 700 °C under N2 atmosphere owns a good conductive network, which results in its superior microwave absorption performance. Herein, at 30wt% filler loading, the effective absorption bandwidth and RLmin of ZC3-700 reach 5.28GHz at 1.90mm and -68.92dB at 1.83mm, respectively. Analyses on microwave absorption mechanism point out the synergistic effect of conduction loss, dipolar polarization and interfacial polarization and magnetic loss on the attenuation of electromagnetic wave. Therefore, ZIF/CS composites and ZIF/CS-derivatives exhibit superior performance on the removal of water pollutants and the absorption of electromagnetic wave, which essentially reveals a multifunctional application of the ZIF/CS composites in the field of environmental protect.

The hollow cubic octahedral structure of Fe3O4 with excellent electromagnetic wave absorption capacity

The unique nanostructure combined with high dielectric and magnetic losses is essential for electromagnetic wave (EMW) attenuation in microwave-absorbing materials (MAM). In this paper, using cubic octahedral Cu2O as a template, we synthesized hollow cubic octahedral Fe(OH)3 at first. After annealing at 450 °C, the hollow cubic octahedral structure Fe3O4 could be obtained. When the filling ratio was 40 %, the minimum reflection loss (RLmin) reached -66.08 dB, and the maximum effective absorption bandwidth (EAB) was 5.38 GHz at a thickness of 1.84 mm, exhibiting improved EMW properties compared with previous works. The hollow cubic octahedral structure of Fe3O4 enhances EMW absorption characteristics, which is attributed to abundant dipole polarization, interface polarization, and good conduction loss. These results indicate that Fe3O4 with the hollow cubic octahedral structure can be used as potential candidates for efficient and broadband EMW absorbers.

Heterogeneous interfaces in 3D interconnected networks of flower-like 1T/2H Molybdenum disulfide nanosheets and carbon-fibers boosts superior EM wave absorption

With the wide application of electromagnetic waves in national defense, communication, navigation and home appliances, the electromagnetic pollution problem is becoming more and more prominent. Therefore, high-performance, and low-density composite wave-absorbing materials have attracted much attention. In this paper, three-dimensional (3D) network structures of flower-like 1T/2H Molybdenum disulfide nanosheets anchored to carbon fibers (1T/2H MoS2/CNFs) were prepared by electrostatic spinning technique and calcination process. The morphology and electromagnetic wave absorption properties were tuned by changing the content of flower-like MoS2. The optimized 1T/2H MoS2/CNFs composite exhibits superior electromagnetic wave absorption with minimum reflection (RLmin) of −42.26 dB and effective absorption bandwidth (EAB) of 6.56 GHz at 2.5 mm. Multi-facts contribute to the super performance. First, the uniquely designed nanosheet and 3D interconnected networks leads to multiple reflection and scattering of electromagnetic waves, which promotes the attenuation of electromagnetic waves. Second, the propriate content of CNFs and MoS2 with different phase regulates its impedance matching characteristic. Third, Numerous heterogeneous interfaces existed between CNFs and MoS2, 1T and 2H MoS2 phase results in interface polarization. Besides, the 1T/2H MoS2 rich in defects induces defect polarization, improving the dielectric loss. Furthermore, the electromagnetic wave absorption performance was proved via radar reflectance cross section simulation. This work illustrates 1T/2H MoS2/CNFs is a promising material for electromagnetic absorption with wide bandwidth, strong absorption, low density, and high thermal stability.

Two-phase magnetic nanospheres with magnetic coupling effect encapsulated in porous carbon to achieve lightweight and efficient microwave absorbers

Component selection is crucial for microwave absorbents. Multi-component absorbers are increasingly useful and can be prepared through the rational design and control of various electrical, magnetic, and other auxiliary components. In this paper, Ni3Fe/NiFe2O4 nanospheres with two-phase magnetism were designed for use as a multi-component absorber. Specifically, a Ni3Fe/ NiFe2O4@SPC composite with 3D networks was successfully fabricated by hydrothermal method, high-temperature carbonization for activation, and electrostatic self-assembly. The contact interface and coupling effect between the two magnetic components can promote the attenuation of electromagnetic waves. Moreover, the introduction of porous carbon successfully inhibits the easy aggregation of the magnetic particles. Impressively, with a filling load of 10 wt%, the optimal RL of the prepared Ni3Fe/NiFe2O4@SPC composite reaches −60.6 dB, and the effective absorption bandwidth is 5.2 GHz at 2 mm. The combination of two magnetic components and porous carbon in this multiphase microwave-absorbing composite demonstrates a feasible strategy for designing efficient microwave absorbers in the future.

Integrating high-efficiency thermal channel construction and structural wave absorption design within vertically oriented SiC-coated carbon fibers/silicone resin composites

To match the increasing miniaturization and integration of electronic devices, higher requirements are put forward for the electromagnetic wave absorption (EWA) and thermal conductivity (Tc) of heat conduction-microwave absorption integrated materials (HCMWAIMs) to overcome the problems of electromagnetic wave (EMW) pollution and heat accumulation. Herein, a simple and efficient shear force induction technique is used to construct a carbon/magnetic isolation network within the silicone resin matrix, where ferrite particles are well dispersed in vertically oriented SiC-coated carbon fibers array. Benefiting from the orderly interconnection of CFs@SiC in the array, the prepared composites have a high Tc of 7.86 W m-1 K-1. The introduction of magnetic ferrite particles within the CFs@SiC array can induce electrical-magnetic coupling, optimize impedance matching, and enhance EMW attenuation. This synergy of V-CFs@SiC/ferrite isolation network structure gives the composites an excellent effective absorption bandwidth (EAB) of 5.88 GHz and a minimal reflection loss (RLmin) of -47.5 dB at a thickness of 1.5 mm. Moreover, the as-prepared composites exhibit outstanding elastic compressibility of 43.2% and rebound rate of 45.1% under a pressure of 35psi. This strategy offers a distinguishing understanding of preparing high-performance HCMWAIMs in modern electronic devices.

Simulation of Rainfall Attenuation Prediction Models for the Optimization of High-Speed Links in Millimeter Bands (80GHz): Tropical Regions’ Case

We deal with the problem of attenuation of electromagnetic waves due to precipitation. Indeed, the millimeter wave frequency (30&amp;ndash;300 GHz) is a promising candidate for broadband wireless networks (4G and beyond), but atmospheric elements limit radio links to this frequency band. Precipitation is the important atmospheric element that causes the attenuation of a wave during its propagation and should therefore be estimated for the proper functioning of a link. It is with this in mind that our study focuses on the choice of an appropriate model for predicting the attenuation of a radio link after simulation of several models proposed in the literature in order to assess the impact of precipitation in the tropical region. The method used to achieve this objective consists firstly of analysing existing models and determining theoretical and actual unavailability using ITU-R methods and the Nomad monitoring tool; then secondly, we develop an application to evaluate the attenuation due to rain using the Da Silva, Mello and ITU-R models. The calculated attenuations were compared to experimental measurements, and Da Silva&amp;#39;s model was found to be the best fit. On a local level, these results have a significant impact on the planning and optimization of communications infrastructures, enabling better performance of networks using millimeter waves. At the national level, this contributes to improved telecommunications networks and more reliable connectivity. Globally, this research can aid the development of high-frequency wireless communications in tropical regions, thereby promoting large-scale technological and economic advancement.

Controlled growth of polyaniline nanofibers on the surface of alkali pre-treated PI fabric as electromagnetic wave-absorbing fabrics

The electromagnetic wave attenuation network composed of PANI NFs is an efficient wave-absorbing structure. Constructing PANI NFs networks on the surface of flexible fabrics is a potential approach to improve the wave-absorbing properties of fabrics, but there are few related reports on this. In this paper, we proposed a facile method to grow PANI NFs (average diameter of 80–100 nm) on the polyimide (PI) fabric surface through a controlled nucleation and growth process. The results of FESEM, FTIR, XPS, and UV–vis indicated that the PANI and PI may first combine at the initial nucleation centers through electrostatic interactions, hydrogen bonding, and π-π stacking, and then the PANI grows linearly into elongated nanofibers under suitable polymerization conditions. As expected, the PANI NFs coated fabric achieved a strong reflection loss (RL) of -34.20 dB (>99.999 % absorption) and a broad effective absorption frequency band of 5–18 GHz. The excellent absorption performance originated from the conduction loss, scattering loss, and polarization relaxation loss of the PANI NFs network. In addition, the fabric exhibits good thermal stability (Td beyond 570 °C) and long-term stability ((90.57 % retention of conductivity after 500 bending cycles). This study provides a viable approach for designing next-generation microwave-absorbing fabric.

Compositional design of C-coated multi-elemental alloy nanoparticles for superior microwave absorption

Exploring improved electromagnetic wave absorption performance in magnetic components involves capitalizing on dual dielectric relaxation and multiple magnetic resonances, ultimately giving rise to a dielectric-magnetic matching effect. Herein, a one-step Metal-organic Chemical Vapor Deposition (MOCVD) method has been utilized to fabricate C-coated ternary and quaternary alloy nanoparticles (FeCoNi, FeCoNiCu, FeCoNiMg, and FeCoNiMn) with tunable magnetization. The results affirm that the capabilities of impedance matching and electromagnetic wave attenuation can be significantly regulated by compositing nanoparticles with different elements. The optimized C-coated FeCoNiMg nanoparticles demonstrate an exceptional capacity for electromagnetic wave attenuation, achieving a reflection loss value of −51.8 dB at a matched thickness of 2.9 mm. Moreover, the absorption bandwidth significantly broadens to 7.60 GHz (10.4 – 18.0 GHz) with a thickness of 2.7 mm. The exceptional performance in electromagnetic attenuation is credited to the dielectric loss and improved impedance matching characteristics induced by the C-coated FeCoNiMg nanoparticles. The findings from this study will be beneficial in the development of lightweight and highly effective electromagnetic wave absorbers using magnetic alloy nanoparticles.

Multi-interfacial bridging engineering of flexible MXene film for efficient electromagnetic shielding and energy conversion

Accompanied by the progressive development of electronic equipment, excellent electromagnetic interference (EMI) shielding materials display a satisfying prospect in protecting electronic devices against electromagnetic pollution/radiation, while integrating energy conversion. Heretofore, it remains a conundrum to availably construct thin films with multi-interfacial bridging engineering as multifunctional shielding devices. To effectively achieve electromagnetic wave attenuation and integrate energy conversion, a co-mixed vacuum-assisted filtration strategy is designed to synthesize Au@MXene/cellulose nanocrystal/dodecylbenzenesulfonic acid-doped polyaniline (AMCP) films. Profited from the interfacial engineering, the total EMI shielding effectiveness (SE) can be increased by 27 % with the highest value of 67.9 dB. MXene with localized surface plasmon resonance characteristics gives the composite films good energy conversion performance, that is, the composite film can be rapidly heated up to 100 °C under the irradiation of an infrared lamp, and its surface temperature remains stable after continuous irradiation. Additionally, the infrared emissivity is as low as 0.173 within the 8–14 μm, which is necessary to adapt various application scenarios. Therefore, it is reliable that the AMCP films constructed by multicomponent offer a facile strategy for MXene-based EMI shielding devices with integration characteristics.

The Electron Migration Polarization Boosting Electromagnetic Wave Absorption Based on Ce Atoms Modulated yolk@shell Fex N@NGC.

The electron migration polarization is considered as a promising approach to optimize electromagnetic waves (EMW) dissipation. However, it is still difficult to realize well-controlled electron migration and elucidate the related EMW loss mechanisms for current researches. Herein, a novel Fex N@NGC/Ce system to construct an effective electron migration model based on the electron leaps among the 4f/5d/6s orbitals of Ce ions is explored. In Fe4 N@NGC/CeSA+Cs+NPs , Ce single-atoms (SA) mainly represent a +3 valence state, which can feed the electrons to Ce4+ of clusters (Cs) and CeO2 nanoparticles (NPs) through a conductive network under EMW, leading to the electron migration polarization. Such electron migration loss combined with excellent magnetic loss provided by Fe4 N core, results in the optimal EMW attenuation performance with a minimum reflection loss exceeds -85.1dB and a broadened absorption bandwidth up to 7.5GHz at 1.5mm. This study clarifies the in-depth relationship between electron migration polarization and EMW dissipation, providing profound insights into developing well-coordinated magnetic-dielectric nanocomposites for EMW absorption engineering.

Use of the 433MHz band for underwater communications in controlled environments

This research aims to design and implement an underwater communication system using radio frequency modules and Arduino. Underwater wireless communication is challenging due to the attenuation of electromagnetic waves in water. However, radio frequency signals in the 433MHz range and the added antenna have shown successful data transfer. For this purpose, measurements are made at different distances, and data is collected in the aquatic environment and free space. A comparative analysis of the values of arrival powers and losses in the studied environment is carried out to verify the efficiency of this study in terms of range, transmission speed, and reliability.

Layered composites made of polymer derived SiOC/ZrB2 reinforced by ZrO2/SiO2 fibers with simultaneous microwave absorption and thermal insulation

To simultaneously improve the microwave absorption and thermal insulation properties of the ceramic materials for stealth high-speed vehicles, layered composites made of polymer-derived SiOC/ZrB2 reinforced by ZrO2/SiO2 fibers were reported in this work. The composites possess a continuous multilayer structure, which was fabricated via the precursor impregnation assisted by hot press curing and pyrolysis using the transparent ZrO2/SiO2 fibers and polymer-derived SiOC and nano ZrB2. The layered composites show an effective absorption band (EAB) of 4.2 GHz at a thickness of 2.9 mm and a minimum reflection loss of –59.34 dB. The exceptional electromagnetic (EM) wave attenuation capability is ascribed to the impedance matching as well as massive EM wave loss caused by the multilayers in which the nano ZrB2 provides interfacial polarization and electrical conduction loss. With a design of the multi-curvature arch structure, a remarkable reduction of radar cross section can be achieved. Besides, the layered composites exhibit good oxidation resistance and thermal insulation when exposed to the dynamic heating environment, demonstrating the potential application in harsh environments used for multifunctional electromagnetic absorbing materials.

Research on the Attenuation of Electromagnetic Waves Suppressed by Traveling Magnetic Fields in Plasma

Research on the Attenuation of Electromagnetic Waves Suppressed by Traveling Magnetic Fields in Plasma

Enhancement of electromagnetic attenuation of network CNT-Carbon microsphere nanocomposites derived from phenolic resin

Carbon nanocomposites have attracted extensive attention due to their excellent electromagnetic attenuation (EMA) properties. Herein, carbon nanocomposites containing the carbon nanotube (CNT)-carbon microsphere (CS) network derived from phenolic resin are prepared, and their EMA properties are investigated. The results show that the microstructure of these carbon nanocomposites can be regulated by a catalyst to transform CSs into CNTs, which ultimately results in the networks forming a “resistor-capacitor” structure. As a result, the minimum reflection loss (RLmin) is −60.77 dB at 2.80 GHz, which is within the S-band, and the maximum effective absorption bandwidth (EAB) is 5.77 GHz. The excellent EMA properties can be attributed to the synergistic effect of heterogeneous interfacial and conduction networks, which induces abundant interfacial polarization and conduction loss. A new solution for achieving a wide absorption band for carbon and high electromagnetic wave attenuation in carbon nanocomposites is proposed.

Synthesis of (WZrNbTaM)C (M = Cr, Ni, Ti) ceramic powders and the electromagnetic wave absorption in 2–18 GHz

AbstractWith the advent of the 5G era, while enjoying the convenience of information in our daily lives, we also face the challenge of dealing with increased and more complex electromagnetic (EM) radiation issues. Therefore, finding EM wave absorbing materials for the operating frequency range (2–18 GHz) of most electronic products has become an important aspect of ensuring human health and environmental safety. In this study, a variety of elements were incorporated into (WZrNbTaM)C powders by calculation and design, where M is Ni, Cr, or Ti. Phase and microstructural analysis demonstrated the successful preparation of a single‐phase solid solution with uniform elements distribution. The magnetic properties of the powders containing Ni and Cr elements exhibited significant improvement. Further analysis revealed that both the impedance matching and EM wave attenuation capabilities of (WZrNbTaCr)C and (WZrNbTaNi)C were enhanced, thereby improving their absorption performance. Compared to (WZrNbTaTi)C, (WZrNbTaCr)C and (WZrNbTaNi)C exhibit a significant improvement in minimum reflection loss (RL), with an increase of 27.1% and 37.2%, reaching −45.21 and −48.79 dB, respectively. The maximum effective absorption bandwidth (EAB) has also increased by 22.9% and 48.6%, reaching 3.44 and 4.16 GHz, respectively. It is noteworthy that (WZrNbTaCr)C and (WZrNbTaNi)C achieved these excellent absorption properties while maintaining a matching thickness of 1.07 and 1.17 mm. This lightweight and thin performance meets the requirements for use in special scenarios while ensuring the outstanding absorption performance.

Strategies to construct conductive structures of polymer-based electromagnetic wave attenuation composites

Varied structure design and preparation approaches of polymer-based composites for electromagnetic wave attenuation.

Attenuation of electromagnetic waves in liquid foams in the frequency range of 1 – 1250 MHz

The purpose of this work is to study the attenuation of electromagnetic waves in the megahertz range (1 – 1250 MHz) in liquid foam structures. We consider issues related to shielding electromagnetic sources and reducing the visibility of metal objects from radar detection and tracking in this range, since such problem is poorly researched. A method of measuring the attenuation of foam structures in segments of strip lines of this range is proposed. Measurements are carried out using an experimental setup based on avector meter and an original strip cell of samples of foam structures with different foaming ratios in the ranges of 13 – 15, 28 – 30, and 50 – 51 units for different foaming agents. The dependencies of foam attenuation on frequency and the dependence on salt additives with concentrations of 1%, 4%, and 6% are found.