Electromagnetic Interference Research Articles

Deep radio interferometric search for decametre radio emission from the exoplanet Tau Boötis b

Detection of electron cyclotron maser (ECM) emission from exoplanets in the 10-40 MHz radio band is likely the only way to measure an exoplanet's magnetic field directly. However, no definitive detection of exoplanetary ECM emission has been made to date. A detection of the hot Jupiter Tau Bo\"otis b was reported but with an observing mode that is not immune to confusion from off-axis interference, making the detection tentative. We searched for radio emissions from Tau Boötis b using the Low Frequency Array (LOFAR) in interferometric mode, which employs direction-of-arrival information to discriminate genuine signals from interference. Our aim was to confirm the previous tentative detection or establish an upper limit in the case of a non-detection. We conducted observations using LOFAR’s Low Band Antenna in interferometric mode, which totalled 64\, hours spread over 8\, nights. We created a custom data-processing pipeline to mitigate common challenges in decametric radio astronomy, including radio frequency interference, ionospheric distortions, and sidelobe noise from nearby bright radio sources. We used this pipeline to image the field around Tau Bo\"otis b, searching for both quiescent and bursting emission from the direction of Tau Bo\"otis b. Despite the high sensitivity of the interferometric observations and extensive data processing, no significant emission was detected from Tau Boötis b in Stokes V. We establish an upper limit of 2 sigma at 24 mJy for any continuous emission from the exoplanet. The previous tentative detection of 400 mJy is thus not confirmed by the interferometric observations. The previous tentative detection is unlikely to be a bona fide astrophysical signal. Our upper limit is lower than the flux density predicted by scaling laws, meaning either the scaling laws need to be revised or the emission from this particular system is beamed away from Earth.

A Review on MXene/Nanocellulose Composites: Toward Wearable Multifunctional Electromagnetic Interference Shielding Application.

With the rapid development of mobile communication technology and wearable electronic devices, the electromagnetic radiation generated by high-frequency information exchange inevitably threatens human health, so high-performance wearable electromagnetic interference (EMI) shielding materials are urgently needed. The 2D nanomaterial MXene exhibits superior EMI shielding performance owing to its high conductivity, however, its mechanical properties are limited due to the high porosity between MXene nanosheets. In recent years, it has been reported that by introducing natural nanocellulose as an organic framework, the EMI shielding and mechanical properties of MXene/nanocellulose composites can be synergically improved, which are expected to be widely used in wearable multifunctional shielding devices. In this review, the electromagnetic wave (EMW) attenuation mechanism of EMI shielding materials is briefly introduced, and the latest progress of MXene/nanocellulose composites in wearable multifunctional EMI shielding applications is comprehensively reviewed, wherein the advantages and disadvantages of different preparation methods and various types of composites are summarized. Finally, the challenges and perspectives are discussed, regarding the performance improvement, the performance control mechanism, and the large-scale production of MXene/nanocellulose composites. This review can provide guidance on the design of flexible MXene/nanocellulose composites for multifunctional electromagnetic protection applications in the future intelligent wearable field.

Improved Electromagnetic Interference Shielding in Lightweight Polyvinylidene Fluoride‐Carbon Nanotube Composite Films

ABSTRACTAs electronic devices become smaller and more common, the problem of electromagnetic interference (EMI) becomes more serious, requiring better shielding solutions. In this study, lightweight polyvinylidene fluoride (PVDF) composite films mixed with multiwalled carbon nanotubes (MWCNT) were developed to improve EMI shielding. A solution casting method and a thin film applicator ensured uniform thickness and flexibility in PVDF‐MWCNT films with varying MWCNT concentrations (0, 0.1, 1, and 2 wt%). Structural and surface properties were analyzed using X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X‐ray spectroscopy (EDS). Dielectric response, AC conductivity, and EMI shielding effectiveness (EMI‐SE) in the Ku band (12–18 GHz) were measured. The PVDF film with 2 wt% MWCNT, at a thickness of 190 ± 10 μm, showed the highest complex permittivity and a record EMI‐SE value of 53.08 dB. This high EMI‐SE is attributed to increased multiple internal reflections within the thin film, enhancing attenuation and reducing reflection losses. These polymer nanocomposites offer a promising and lightweight option for advanced EMI shielding in the growing number of electronic devices.

Resource-Efficient FPGA Architecture for Real-Time RFI Mitigation in Interferometric Radiometers

Interferometric radiometers operating at L-band, such as ESA’s SMOS mission, enable crucial Earth observations providing high-resolution measurements of soil moisture, ocean salinity, and other geophysical parameters. However, the increasing electromagnetic spectrum utilization has led to significant Radio Frequency Interference (RFI) challenges, particularly critical given the sensors’ fine temperature resolution requirements of less than 1 K. This work presents the hardware implementation of an advanced RFI detection and mitigation algorithm specifically designed for interferometric radiometers, targeting future L-band missions. The implementation processes 1-bit quantized signals at 57.69375 MHz from multiple receivers, employing time-frequency analysis and polarimetric detection techniques while optimizing Field Programmable Gate Array (FPGA) resource utilization. Novel optimization strategies include overclocked processing cores operating at 230.775 MHz, efficient resource sharing through operation serialization, and strategic memory management. The system achieves real-time processing capabilities while maintaining detection probabilities above 63% with false alarm rates below 1% for typical interference scenarios. Performance validation using synthetic datasets demonstrates robust operation across various RFI conditions, making this implementation suitable as part of the RFI detection and mitigation efforts for future interferometric radiometer missions beyond SMOS.

Bottom-up engineering strategies for electromagnetic shielding wood-based composites through Ca2+ crosslink and graphene incorporation

ABSTRACT Sustainable electromagnetic interference shielding materials that combine environmental friendliness, robustness, and enhanced performance are critically needed for national development strategies. Wood-based materials, particularly woodchips, are desirable due to their chemical similarity to wood and the potential to eliminate anisotropic properties. In this study, chemically treated woodchips to expose the cellulose within them. The interactions between woodchips, graphene, and calcium ions (Ca²+) was studied to create innovative electromagnetic shielding wood-based materials using a bottom-up approach. Compared to composites formed via hydrogen bonding cross-linking, the introduction of calcium ions significantly increased the degree of cross-linking and improved the mechanical properties of the composites. This resulted in a tensile strength of 9.8 MPa, compressive strength of 43.8 MPa, and flexural strength of 22.3 MPa. By incorporating graphene, an optimal conductive network was established. At a sawdust-to-graphene ratio of 1:1, the material's conductivity and shielding effectiveness were 100 S/cm and 49 dB, respectively, meeting the standards for commercial and residential EMI shielding applications. Moreover, this composite material addresses the anisotropy and inconsistent mechanical properties of natural wood, showing significant potential in the area of green electronics.

Optimal Rotor Design for Reducing Electromagnetic Vibration in Traction Motors Based on Numerical Analysis

Interior permanent magnet synchronous motor (IPMSM) for traction applications have attracted significant attention due to their advantages of high torque and power density as well as a wide operating range. However, these motors suffer from high electromagnetic vibration noise due to their complex structure and structural rigidity. The main sources of this electromagnetic vibration noise are cogging torque, torque ripple, and radial force. To predict electromagnetic vibration noise, finite element analysis (FEA) with flux density analysis of the air gap is essential. This approach allows for the calculation of radial force that is the source of the vibration and enables the prediction of vibration in advance. The data obtained from these analyses provide important guidance for reducing vibration and noise in the design of electric motors. In this paper, the cogging torque and vibration at rated and maximum operating speed are analyzed, and an optimal cogging torque and vibration reduction model, with rotor taper and two-step skew structure, is proposed using the response surface method (RSM) to minimize them. The validity of the proposed model is demonstrated through formulations and FEA based entirely on numerical analysis and results. This study is expected to contribute to the design of more efficient and quieter electric motors by providing a solution to the electromagnetic vibration noise problem generated by IPMSM for traction applications with complex structures.

Tailoring the Properties of 2D Nanomaterial‐Polymer Composites for Electromagnetic Interference Shielding and Energy Storage by 3D Printing—A Review

3D‐printed 2D nanomaterials‐based polymer composites, with their exceptional electrical conductivity and structural functionalities, have become leading‐edge engineering materials for electromagnetic interference (EMI) shielding, sensors, and energy storage applications. This review begins with a brief introduction to various types of 2D nanomaterials and their fabrication techniques, specifically different types of 3D printing. The subsequent sections highlight key factors such as rheological properties, surface tension, additives, and binders that influence the printability of 2D nanomaterials‐based polymer composites. The advancements in 2D nanomaterials‐based polymers, including MXene, graphene, and graphene derivatives, are then presented. The interaction, dispersion, and/or network formation of 2D nanomaterials in the polymer matrix is a crucial factor in determining the electrical performance of the composites. This review also discusses surface modification strategies for 2D nanomaterials to enhance their sensing, EMI shielding, and energy storage capabilities. Finally, the impact of various 3D‐printed polymer composite geometries, such as rectangular, cylinder, and circular, on shielding performance is thoroughly examined, engaging the reader in the exploration of these materials.

Cybersecurity Challenges in UAV Systems: IEMI Attacks Targeting Inertial Measurement Units

The rapid expansion in unmanned aerial vehicles (UAVs) across various sectors, such as surveillance, agriculture, disaster management, and infrastructure inspection, highlights the growing need for robust navigation systems. However, this growth also exposes critical vulnerabilities, particularly in UAV package delivery operations, where intentional electromagnetic interference (IEMI) poses significant security and safety threats. This paper addresses IEMI attacks targeting inertial measurement units (IMUs) in UAVs, focusing on their susceptibility to medium-power electromagnetic interference. Our approach combines a comprehensive literature review and QuickField simulation with experimental validation using a commercially available 6-degree-of-freedom (DOF) IMU sensor. We propose a hardware-based electromagnetic shielding solution using mu-metal to mitigate IEMI’s impact on sensor performance. The study combines experimental testing with simulations to evaluate the shielding effectiveness under controlled conditions. The results of the measurements showed that medium-power IEMI significantly distorted IMU sensor readings, but our proposed shielding method effectively reduces the impact, improving sensor reliability. We demonstrate the mechanisms by which medium-power IEMI disrupts sensor operation, offering insights for future research directions. These findings also highlight the importance of integrating hardware-based shielding solutions to safeguard UAV systems against electromagnetic threats.

Phase‐Transition Microcapacitor Network in Organohydrogel for Absorption‐Dominated Electromagnetic Interference Shielding and Multi‐Mode Intelligent Responsiveness

AbstractHydrogels/organohydrogels show promise for flexible, intelligent electromagnetic interference (EMI) shielding, yet simultaneously achieving absorption‐dominated shielding performance, excellent mechanical properties and multi‐mode intelligent responsiveness remains challenging. This study presents a microcapacitor network strategy as an alternative to the traditional conductive percolation network for EMI shielding materials. Paraffin‐nanoclay/MXene core‐shell microspheres are uniformly integrated into the hydrogel matrix via in situ polymerization, forming a microcapacitor network where the microsphere shells and hydrogel serve as capacitor plates and dielectric layers, respectively. Microcurrents and interfacial polarization at capacitor plates, along with dipole polarization within dielectric layer, significantly promote EM wave attenuation for absorption‐dominated EMI shielding (absorption coefficient >0.7). Meanwhile, the abundant hydrogen bonds and paraffin phase synergistically enhance mechanical strength (≈0.64 MPa) and stretchability (elongation at break > 1000%). Due to the solid‐liquid phase transition of the paraffin phase in microspheres, organohydrogel exhibits a unique ability to retain high‐temperature shielding performance at room temperature. This feature enhances room‐temperature shielding effectiveness and enables multi‐mode intelligent responsiveness. Under the same room‐temperature deformation mode, it exhibits programmable shielding performance regulation in response to different external stimuli, following room‐temperature changes or simulating high‐temperature changes.

Study on Self-tuning of Robot Parameters for EMC Vehicle Steering Test

With the continuous advancement of electric vehicles and smart internet technologies, ensuring vehicle safety through electromagnetic compatibility (EMC) testing in complex electromagnetic environments has become increasingly critical. However, due to the significant variability in vehicle response characteristics under electromagnetic interference, traditional PID control methods for steering robots struggle to meet the high-precision requirements of such tests. In this study, a novel fuzzy PID parameter self-tuning method is proposed, leveraging a Sparrow Search Algorithm-Back Propagation (SSA-BP) neural network. This method optimizes the fuzzy controller's quantization factor by constructing a neural network system where the expected motor angle serves as the input and the quantization factor as the output. The quantization factor is then calibrated online through iterative training.The proposed approach enables the steering robot to achieve real-time, adaptive tuning of the PID parameters for the drive motor by adjusting the steering torque according to different vehicle characteristics, thereby enhancing the robot's anti-interference capability and robustness in EMC testing. The effectiveness of this method is validated through Matlab/Simulink simulations, experiments conducted on the Sensodrive platform, and tests performed in an EMC anechoic chamber. The results indicate that the method offers substantial improvements in control accuracy and anti-interference capabilities, highlighting its strong potential for practical application.

Asymmetric hybrid carbonaceous membranes with exceptional electromagnetic interference shielding and superior electro-photo-thermal performance

Asymmetric hybrid carbonaceous membranes with exceptional electromagnetic interference shielding and superior electro-photo-thermal performance

Manganese–cobalt ferrite and polyaniline core–shell nanocomposite as an efficient shielding material against electromagnetic interference under X-band frequency

Manganese–cobalt ferrite and polyaniline core–shell nanocomposite as an efficient shielding material against electromagnetic interference under X-band frequency

Modeling on High‐Frequency Parasitic Parameters of Artificial Mains Network Based on Improved Differential Evolution Algorithm

ABSTRACTThe performance of the artificial mains network (AMN) has an important influence on the accuracy of the conducted electromagnetic interference (EMI) noise measurement. The high‐frequency features of the AMN like impedance and voltage division factor (VDF) should be calibrated to enhance the precision of the conducted EMI noise measurement. Because the parasitic parameters of passive devices at high‐frequency have a significant influence on the performance of the AMN, a high‐frequency model of the AMN with parasitic parameters is established in the current study, and the high‐frequency parasitic parameters are extracted based on an improved differential evolution (DE) algorithm and AMN topology. The live wire impedance and VDF of R&S AMN ENV216 are obtained according to the presented approach. The results of the proposed method are compared with those extracted using the scattering parameters and a vector network analyzer, and the effectiveness of the method is validated. This study will aid in the calibration of the AMN and contribute to the accurate measurement of conducted EMI noise in electronic devices.

COSMIC-2 RFI Prediction Model Based on CNN-BiLSTM-Attention for Interference Detection and Location.

As the application of the Global Navigation Satellite System (GNSS) continues to expand, its stability and safety issues are receiving more and more attention, especially the interference problem. Interference reduces the signal reception quality of ground terminals and may even lead to the paralysis of GNSS function in severe cases. In recent years, Low Earth Orbit (LEO) satellites have been highly emphasized for their unique advantages in GNSS interference detection, and related commercial and academic activities have increased rapidly. In this context, based on the signal-to-noise ratio (SNR) and radio-frequency interference (RFI) measurements data from COSMIC-2 satellites, this paper explores a method of predicting RFI measurements using SNR correlation variations in different GNSS signal channels for application to the detection and localization of civil terrestrial GNSS interference signals. Research shows that the SNR in different GNSS signal channels shows a correlated change under the influence of RFI. To this end, a CNN-BiLSTM-Attention model combining a convolutional neural network (CNN), bi-directional long and short-term memory network (BiLSTM), and attention mechanism is proposed in this paper, and the model takes the multi-channel SNR time series of the GNSS as the input and outputs the maximum measured value of RFI in the multi-channels. The experimental results show that compared with the traditional band-pass filtering inter-correlation method and other deep learning models, the model in this paper has a root mean square error (RMSE), mean absolute error (MAE), and correlation coefficient (R2) of 1.0185, 1.8567, and 0.9693, respectively, in RFI prediction, which demonstrates a higher RFI detection accuracy and a wide range of rough localization capabilities, showing significant competitiveness. Since the correlation changes in the SNR can be processed to decouple the signal strength, this model is also suitable for future GNSS-RO missions (such as COSMIC-1, CHAMP, GRACE, and Spire) for which no RFI measurements have yet been made.

3D Printed Carbon Nanotube/Phenolic Composites for Thermal Dissipation and Electromagnetic Interference Shielding.

Here we demonstrate direct ink write (DIW) additive manufacturing of carbon nanotube (CNT)/phenolic composites with heat dissipation and excellent electromagnetic interference (EMI) shielding capabilities without curing-induced deformation. Such polymer composites are valuable for protecting electronic devices from overheating and electromagnetic interference. CNTs were used as a multifunctional nanofiller to improve electrical and thermal conductivity, printability, stability during curing, and EMI shielding performance of CNT/phenolic composites. Different CNT loadings, curing conditions, substrate types, and sample sizes were explored to minimize the negative effects of the byproducts released from the cross-linking reactions of phenolic on the printed shape integrity. At a CNT loading of 10 wt %, a slow curing cycle enables us to cure printed thin-walled CNT/phenolic composites with highly dense structures; such structures are impossible without a filler. Moreover, the electrical conductivity of the printed 10 wt % CNT/phenolic composites increased by orders of magnitude due to CNT percolation, while an improvement of 92% in thermal conductivity was achieved over the neat phenolic. EMI shielding effectiveness of the printed CNT/phenolic composites reaches 41.6 dB at the same CNT loading, offering a shielding efficiency of 99.99%. The results indicate that high CNT loading, a slow curing cycle, flexible substrates, and one thin sample dimension are the key factors to produce high-performance 3D-printed CNT/phenolic composites to address the overheating and EMI issues of modern electronic devices.

Capillarity‐Assisted 3D Patterning of Liquid Metal

AbstractFlexible electronics with sophisticated 3D architectures enable multidimensional functionalities and multi‐component integration, thus surpassing their 2D counterparts in soft robotics and wearable sensors. Because of its unique metallic and fluidic characteristics, liquid metal (LM) has proven to be an excellent material for fabricating flexible electronics. However, its low viscosity and high surface tension have primarily restricted LM to the creation of 2D‐patterned films on flat surfaces, significantly limiting the complexity and functionality of the resulting flexible devices. In this work, inspired by the capillary‐driven liquid flow in a hierarchical lattice matrix, a 3D patterning method is proposed for LM and extended to the fabrication of porous materials with flexible conductivity. The feasibility and versatility of the proposed method are showcased by fabricating tunable electromagnetic interference shielding materials, programmable 3D circuits, and customizable wearable sensors, highlighting its potential for promoting the development of integrated circuits and wearable electronics.

Popcorn Effect-inspired Self-propagating Formation of High-conductivity Cement Composite for Multifunctional Applications.

The surge in modern civil technologies demands a transformation in cement composites to surpass traditional roles and integrate smart functionalities. In this regard, enhancing the electrical conductivity of cement composites is a critical challenge. This study introduces a novel strategy for the self-propagating formation of expandable graphite-based high-conductivity cement composites through a simple thermal treatment with 3wt.% expandable graphite and 1wt.%carbon fiber as conductive fillers. Inspired by the popcorn effect, this method leverages the rapid expansion of graphite at high temperatures, promoting contact between conductive fillers and forming new conductive networks. The obtained composites demonstrate a remarkable reduction of 60% in electrical resistance after heat treatment compared to the electrical resistance of standard cement composites, and the enhancing mechanisms is explored. The conductive properties endow the material with excellent electrothermal (>100 °C at 10V), electrothermochromic (response time of 2 s), and electromagnetic interference shielding (42dB at 12.4GHz) performance. This innovative approach provides vast opportunities for developing smart infrastructure with enhanced electrical properties, regarded as a promising candidate for promoting next-generation buildings and infrastructures.

Electromagnetic Trigger Effects in the Ionosphere–Atmosphere–Lithosphere System and Their Possible Use for Short-Term Earthquake Forecasting

Previously conducted numerical studies of the influence of class X solar flares on seismic activity have shown that the absorption of X-ray radiation from a solar flare in the ionosphere can cause pulsations of the geomagnetic field up to 100 nT and the corresponding generation of telluric currents in faults in the Earth’s crust with a density of up to 10–6 A/m2, which is comparable to the current density created in the Earth’s crust by artificial pulse sources and leading to the initiation of weak earthquakes in the Pamirs and Northern Tien Shan. To verify these numerical results, an analysis was conducted of the possible impact of the 50 strongest class X flares (1997–2023) on both global seismic activity and earthquake-preparation zones located only on the illuminated part of the globe. The method of superimposing epochs has established an increase in number of earthquakes M ≥ 4.5 within 10 days after a solar flare, especially in the area with a radius of 5000 km around the subsolar point (up to 68% for flare class X5), compared to the same period before it. Analysis of aftershock activity of the strong Sumatra–Andaman earthquake (M = 9.1, December 26, 2004) showed that the number of aftershocks with magnitude M ≥ 2.5 increased more than 17 times after the X10.1 class solar flare (January 20, 2005) with a delay of 7–8 days. In addition, it has been shown that solar flares of class X2.3 and M3.64, which occurred after the Darfield earthquake (M = 7.1, September 3, 2010, New Zealand), in the area of subsolar points of which the aftershock zone was located, probably caused three strong aftershocks (M6.3, M5.2, and M5.9) with the same delay of 6 days on the Port Hills fault, which is the most sensitive to external electromagnetic influences in terms of its electrical conductivity and orientation. Taking into account the concept of earthquake forecasting based on trigger effects proposed by G.A. Sobolev, the possibility is discussed of using the obtained results for short-term forecasting as additional information along with known precursors.

Hierarchical Polyimide Nonwoven Fabric with Ultralow-Reflectivity Electromagnetic Interference Shielding and High-Temperature Resistant Infrared Stealth Performance

Designing and fabricating a compatible low-reflectivity electromagnetic interference (EMI) shielding/high-temperature resistant infrared stealth material possesses a critical significance in the field of military. Hence, a hierarchical polyimide (PI) nonwoven fabric is fabricated by alkali treatment, in-situ growth of magnetic particles and "self-activated" electroless Ag plating process. Especially, the hierarchical impedance matching can be constructed by systematically assembling Fe3O4/Ag-loaded PI nonwoven fabric (PFA) and pure Ag-coated PI nonwoven fabric (PA), endowing it with an ultralow-reflectivity EMI shielding performance. In addition, thermal insulation of fluffy three-dimensional (3D) space structure in PFA and low infrared emissivity of PA originated from Ag plating bring an excellent infrared stealth performance. More importantly, the strong bonding interaction between Fe3O4, Ag, and PI fiber improves thermal stability in EMI shielding and high-temperature resistant infrared stealth performance. Such excellent comprehensive performance makes it promising for military tents to protect internal equipment from electromagnetic interference stemmed from adjacent equipment and/or enemy, and inhibit external infrared detection.

Carbon Nanofiber/Polyaniline Composite Aerogel with Excellent Electromagnetic Interference Shielding, Low Thermal Conductivity, and Extremely Low Heat Release

Abstract The rapid development of communication technology and high-frequency electronic devices has created a need for more advanced electromagnetic interference (EMI) shielding materials. In response to this demand, a study has been conducted to develop multifunctional carbon nanofibers (CNFs)/polyaniline (PANI) aerogels with excellent electromagnetic interference shielding, flame retardancy, and thermal insulation performance. The process involved freeze-drying of electrospun CNFs and PANI nanoparticles followed by in situ growth PANI to coat the CNFs, creating the core–shell structured CNFs/PANI composite fiber and its hybrid aerogels (CP-3@PANI). The interaction between PANI and aniline (ANI) provides attachment sites, allowing additional ANI adsorption into the aerogel for in situ polymerization. This results in PANI uniformly covering the surface of the CNFs, creating a core–shell composite fiber with a flexible CNF core and PANI shell. This process enhances the utilization rate of the ANI monomer and increases the PANI content loaded onto the aerogel. Additionally, effective connections are established between the CNFs, forming a stable, conductive three-dimensional network structure. The prepared CP-3@PANI aerogels exhibit excellent EMI shielding efficiency (SE) of 85.4 dB and specific EMI SE (SE d−1) of 791.2 dB cm3 g⁻1 in the X-band. Due to the synergistic flame-retardant effect of CNFs, PANI, and the dopant (phytic acid), the CP-3@PANI aerogels demonstrate outstanding flame-retardant and thermal insulation properties, with a peak heat release rate (PHRR) as low as 7.8 W g⁻1 and a total heat release of only 0.58 kJ g⁻1. This study provides an effective strategy for preparing multifunctional integrated EMI shielding materials.