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An analytical method is introduced to assess the susceptibility of radio altimeter (RA) receivers to adjacent-band fifth-generation (5G) signal interference and to quantify its impact on RA performance. The power-series method is employed to analyze the intermediate frequency (IF) signal gain compression effect of 5G signal interference on RA receivers. A behavioral-level simulation model of the RA receiver’s radio frequency (RF) front-end is constructed based on the advanced design system (ADS), and a 5G signal injection simulation is performed. The simulation results indicate that 5G signals can induce nonlinear effects in the RF front-end circuit of the RA, leading to IF signal gain compression, thereby affecting the subsequent signal processing of RA receivers. The interference effect on the RA receiver is influenced by factors such as the power and frequency of the 5G interference signal. To investigate this, an interference injection test was conducted on a specific RA receiver to validate the aforementioned interference mechanisms. The test results indicate that when the average power of the injected 5G signal at a frequency of 4000 MHz reaches −16 dBm, the IF signal power is significantly reduced. As the power of the 5G signal increases, this nonlinear effect becomes more pronounced. Furthermore, the height error ratio significantly increases, with consistent trends observed across different test frequencies. The interference threshold for the RA is lower when the signal frequency is closer to the RA operational signal frequency. Our research results demonstrate the efficacy of this method, providing a reference basis for studies on interference mechanisms and the evaluation of interference effects related to RA receivers within the electromagnetic environment of 5G signals.

Skin depth is a fundamental material property that governs the electromagnetic behavior of materials. Unfortunately, there are significant and common pitfalls in the analysis of the experimental results on electromagnetic absorption for the purpose of determining skin depth. This commentary is aimed at covering theses pitfalls for the first time.

Herein, we report terahertz (THz) shielding of flexible MXene (Ti 3 C 2 T x )/MWCNT/PVA polymer composite films by using THz time-domain spectroscopy (THz-TDS) in 0.1–2.0 THz frequency range. The polymer composite with 42 µm thickness exhibited an excellent shielding effectiveness of 36 dB at 2 THz which is much higher than most of the reported materials for THz shielding with comparable thickness. The absorption coefficient increases from 100 cm −1 for pristine PVA to ~ 600 cm −1 for 20 wt% MXene/1.5 wt% MWCNT/PVA composite. The high THz shielding of flexible MXene/MWCNT/polymer composite is ascribed to the good electrical conductivity and interfacial synergistic effect of 1D/2D nanostructures that promoted the shielding of electromagnetic waves. Our simple solution casting methodology for fabrication of thin films and subsequent high THz shielding opens possibilities to design MXene-based polymer composites for THz applications.

Conductive aerogel is a material with excellent electrical conductivity and unique three-dimensional nano-network structure, formed by doping conductive fillers into the aerogel, or directly through conductive substances such as conductive polymer. In addition, it has the advantages of high porosity, high specific surface area, low density, excellent flexibility and low cost. The purpose of this review is to summarize the research status of conductive aerogels to open up new ideas for scientific research in related fields for readers. Firstly, we summarize the assembly strategies of conductive aerogel. The assembly process includes preparation and drying of the gel. In addition, the aging process is involved. Secondly, we review its conduction mechanism. Then, the effects of pressure, temperature and humidity on the properties of conductive aerogels are summarized. Notably, conductive aerogel has piezoresistive effect because of its elasticity and compressibility. Finally, based on the properties of conductive aerogels and their advantages in electrical conductivity, we summarize the applications of conductive aerogels in supercapacitor, electrocatalysis, sensors and electromagnetic interference shielding. This review summarizes the current development and application of conductive aerogel in recent years, which provides strong support for the future development of conductive aerogel. Graphical abstract

The development of electronic and communication technology keeps us updated, but it also creates electromagnetic interference (EMI), which causes infrastructure, hospitals, military facilities, nuclear power plants and delicate devices to malfunction. Therefore, it is crucial to stop the EMI-related infrastructure and electronic component failure. Copper-coated textiles are one potential example of the electrically conducting materials that might be utilized to provide an EMI shielding. However, the copper-coated materials’ performance is typically reduced by chemical and mechanical deterioration, especially when it comes to EMI shielding. In this work, we have improved their durability of Cu-coated nonwoven fibrous materials (Milife fabric) by simple silanization treatment. Later, the mechanical and chemical stability was assessed in terms of their morphology and EMI shielding effectiveness (EMSE). The silane coating helps to protect the Cu layer from degradation due to mechanical forces and chemical environment. Silanes also be a key element in obtaining improve the EMI shielding properties for a longer period. The formation of conductive structures on the fibrous materials was observed using a scanning electron microscope (SEM), which further confirms the effect of silane coating on chemical stability, abrasion and washing resistance of Cu-coated fibrous materials (cMi) was analyzed. In addition to this, the EMSE values of the silane-coated cMi fibrous materials were used to evaluate the physical, chemical and mechanical stability of the materials.

The present study focuses on the development of radar-absorbing materials (RAM) for electromagnetic interference shielding. Herein, we report on the synthesis of MnFe 2 O 4 , Fe 3 O 4 , and cobalt (Co) nanoparticles and their nanocomposites with multi-walled carbon nanotubes (MWCNTs). Characterization techniques including XRD, SEM and VSM were used to confirm the successful formation of nanoparticles and their composites. The nanocomposites showed strong radar absorption properties in the frequency range of 1–20 GHz due to the synergistic effect of MWCNTs and magnetic nanoparticles. Among other nanocomposites, MWCNTs/Fe 3 O 4 demonstrated an extremely high electromagnetic wave absorption with a reflection loss min value of − 35.22 dB at 14.2 GHz and RL min of − 16.74 dB at 19.17 GHz. This study offers insights into designing advanced RAM, highlighting potential for next-gen electromagnetic wave absorbers.

In recent years, epoxy composites have been found as a great composite material in the design and fabrication of parts for industrial applications, owing to their cost-effectiveness, ease of processing, and excellent properties. However, reports have it that epoxy nanocomposites still face properties degradation on exposure to lightening strikes during performance, especially on aerospace applications. And such limitation of epoxy-reinforced composites occurs due to their poor electrical conductivity and low resistance to thermal effect. Thus, the present review study focuses on the recent advances on improving the mechanical, thermal, and electrical conductivity properties of epoxy-reinforced nanocomposites using carbon-based nanofillers. In addition, the study highlights the potential applications of epoxy nanocomposites in sensors, automobiles, electromagnetic interference shielding, and aerospace. As such, the authors concluded the review with advancement, challenges, and recommendations on the future improvement of epoxy-reinforced conductive nanofiller composites. Additionally, in the field of conductive polymer nanocomposites field of applications, the review will also open an avenue for future study.

Tunable, wearable and transparent electromagnetic interference (EMI) shielding materials are seeking great research interest in the fabrication of smart EM devices. In this context, the exploitation of multifunctional hydrogels with excellent mechanical and transparent properties along with EMI shielding effectiveness is an emerging alternative and a great challenge as well. Here, we report a flexible, transparent and pressure-sensitive EMI shielding material with excellent mechanical properties (tensile strength ~ 1.53 MPa) based on the synergistic effect of ionic compounds such as 1-butyl-3-methylimidazolium chloride (BMIMCl) and lithium chloride (LiCl)-loaded hydrogel-elastomer, i.e., polyacrylamide (PAM)/sodium alginate (Alg)-PDMS hybrid. The synergistic effect induced by IL and LiCl in PAM-Alg hydrogel alters the ionic conductivity as well as EMI shielding effectiveness (SE) (~ 45.76 dB) performance, which are higher than the corresponding PAM-Alg (~ 28.12), PAM-Alg-IL (~ 38.11 dB) and PAM-Alg-Li hydrogel (~ 32.98 dB). Furthermore, the fabricated hydrogel (IL and LiCl in PAM-Alg) showed a decrement in relative resistance change under different physical compression. Interestingly, the EMI SE of the ion-loaded hydrogel is ~ 65.08 dB under physical compression and ~ 46.99 dB after release. It also showed the EMI SE T (total EMI shielding effectiveness) value of ~ 23.81 dB at freezing conditions. However, to check the sustainability of the hydrogel under a harsh environment, a thin PDMS layer was formed on its surface with a little sacrifice of EMI SE T of ~ 4 dB than the unwrapped one. Thus, these findings explore an innovative strategy to fabricate a smart EMI shielding material for futuristic development in innovative electronics. Graphical Abstract

Conventional wave-absorbing materials effectively absorb electromagnetic waves in specific frequency bands and however cannot cope with interference and radiation in a wide frequency range. Therefore, materials with broadband wave-absorbing properties are of great significance for electromagnetic interference and radiation, protection of equipment, and human health. In this experiment, carbon nanotubes/nickel–zinc ferrite/polyaniline complex and carbon nanotubes/barium–zinc ferrite/polyaniline polymers were prepared by solution blending and in situ polymerization, respectively. The results show that the carbon nanotube/NiZn ferrite/polyaniline complexes has a good impedance matching absorption effect with a peak of − 34.3 dB at 3.68 GHz prepared by solution reaction method and with a maximum reflection loss of − 28.95 dB at 12.44 GHz by in situ polymerization method. Carbon nanotube/barium–zinc ferrite/polyaniline complexes were prepared by solution reaction and in situ polymerization methods, and the samples prepared by in situ polymerization had better absorption properties, with an effective absorption bandwidth up to 8.9 GHz (6.5–14.6 GHz and 16.1–16.8 GHz) and a reflection loss reaching a maximum of − 37.95 dB at 12.84 GHz.

The present work aimed at the development of lightweight EMI shielding epoxy-based composites with high mechanical strength for aircraft application. In this regard, we prepared CuO-activated carbon nanoparticles by the simple co-precipitation method. The different weight ratios (5, 10 and 15 wt%) of the CuO-activated carbon/epoxy composites are prepared, and their mechanical and EMI shielding properties have been studied. To achieve high mechanical and EMI shielding efficiency, the optimum composition of CuO-activated carbon/epoxy composite matrix is reinforced with the carbon fiber. The carbon fiber-reinforced CuO-activated carbon/epoxy hybrid composite exhibits high thermal and mechanical properties. The synergistic effect of carbon fiber and the 10 wt% CuO-activated carbon/epoxy composite matrix with excellent dielectric and ohmic losses delivered the highest electromagnetic interference shielding effectiveness value of 52.02 dB at 11.48 GHz. Hence, the composite with superior thermal and mechanical properties can be used as a prominent electromagnetic shielding material in aircraft application.