Analysis and Characterization of Shielding Material for Mitigating Electromagnetic Interference in UAVs

Off/on switchable smart electromagnetic interference shielding aerogel

Electromagnetic interference (EMI) due to lightning strike in Unmanned Aerial Vehicle (UAV) became a critical issue, since it could cause a severe damaged to electronic equipment which was installed in UAV. This paper proposed a method to reduce EMI by creating shield over the body of UAV with aluminum foil with thickness 0.15mm. A standard lightning impulse-voltage generated by impulse generator was delivered to the high voltage (HV) electrode at a particular distance from UAV. Indirect effect of lightning strike was investigated by measuring induced voltage inside the compartment of UAV fuselage during flashover between the HV electrode and UAV. Flashover between the HV electrode and UAV simulated the lightning strike. The result showed that the highest voltage only 1V at UAV compartment when 150kV impulse voltage supplied to the electrode with striking area on the wing. The measured voltage was far below 100V as the insulation level of low voltage equipment inside UAV. Although the direct effect of lightning has created a burning hole on the surface aluminum foil with thickness 0.15mm, the effect was overcome by increasing the thickness to 0.3mm. The application of aluminum foil over the surface of UAV repelled the electromagnetic interference which acted as a Faraday cage. The shielding method was successfully reduced the effect of EMI.

Lightweight HfC nanowire-carbon fiber/graphene aerogel composites for high-efficiency electromagnetic interference shielding

Carbon nanotubes films in glass fiber polymer matrix forming structures with high absorption and shielding performance in X-Band

Flexible transparent conductive films (FTCFs) with electromagnetic interference (EMI) shielding performance are increasingly crucial as visualization windows in optoelectronic devices due to their capabilities to block electromagnetic radiation (EMR) generated during operation. Metal mesh-based FTCFs have emerged as a promising representative in which EMI shielding effectiveness (SE) can be enhanced by increasing the line width, reducing the line spacing, or increasing mesh thickness. However, these conventional approaches decrease optical transmittance or increase material consumption, thus compromising the optical performance and economic viability. Hence, a significant challenge still remains in the realm of metal mesh-based FTCFs to enhance EMI SE while maintaining their original optical transmittance and equivalent material usage. Herein, we propose an innovative symmetric structural optimization strategy to create silver mesh-based sandwich-FTCFs with arbitrary customized sizes through high-precision extrusion printing technology for tunable EMI shielding performance. The meticulous adjustment of xy-axis offsets and printing starting point ensures perfect alignment of the silver mesh on both sides of the transparent substrate. This approach yields sandwich-FTCFs with optical transmittance equivalent to single-layer-FTCFs under identical parameters while simultaneously achieving up to 40% enhanced EMI SE. This improvement stems from the synergistic effect of multiple internal reflections and wave interference between the symmetric silver meshes. The excellent shielding performance of sandwich-FTCFs is evidenced through effectively blocking electromagnetic waves from common devices such as mobile phones, Bluetooth earphones, and smartwatches. Our work represents a significant advancement in balancing optical transmittance, EMI SE, and material efficiency in high-performance and cost-effective FTCFs.

Investigation of electromagnetic shielding effectiveness of nano silver coated stainless steels

Unmanned aerial vehicles (UAVs) are widely used in many domains and they are sensitive to electromagnetic radiation. It is very important to learn the electromagnetic environment effect on UAV. In this paper, we present a novel method to test susceptibility of UAV to intentional electromagnetic interference (IEMI). By using the method, radiated susceptibility test is carried out on a kind of UAV towards continuous wave. The results show that even the radiated electric field is lower than 1 V/m, the data link of the UAV used to communicate with the ground control station can be disrupted when the frequency of the radiated continuous wave is the same as or close to the UAV's data link. Some of the sensitive frequencies, such as 1/2, 1/3, 1/4, 1/5 times of the working frequency, leading to the disruption of the data link are obtained because of harmonics produced by nonlinear units, e.g. amplifier, in the continuous wave emission system. The coupling path between the UAV and IEMI and the mechanism leading to the communication interruption of the UAV are further analysed by injection method.

Harmful electromagnetic (EM) interference (EMI) to living beings and various sensitive instruments by EM radiations from electronic and electrical gadgets and mobile towers is increasing rapidly. It inflicts illness, and presumably cancerous growth in human cells. EMI is minimized by wrapping the receiver and/or the emitter gaplessly by an efficient EM shielding sheet. Compared to the widely used and classical metallic shields, 2nd generation polymer composite EMI shields are lighter and more flexible. Conventional polymer composites use conducting polymers and metallic/carbon powders that have conducting electrons to reflect EM waves away. A polymeric binder, curing overnight to a soft and flexible sheet, has presently been selected for making the polymeric composites. We test EM shielding by certain non‐metallic composites. We review results for composites with fine metallic fibers (copper and brass turnings, available as waste from mechanical workshops) or conducting forms of cadmium oxide or ferroelectric materials (PbNb2O6 [o‐PN] & BaTiO3 [BT]) or their mixtures (52 samples). Small pieces of these cloth‐like polymeric sheets have been characterized in a Vector Network Analyzer (VNA), by measuring input power (Pin), the reflected power (Prefl), and the transmitted power (Pout), over five frequency bands in 700 MHz to 40 GHz range to find Shielding Effectiveness (SE) = 10 log (Pout/Pin) and Reflection Effectiveness = 10 log (Prefl/Pin). Success of o‐PN, BT, conducting (fired) Cd‐O, metallic turnings and their combinations has been discussed, highlighting some new observations. Composites, developed in this work, include EMI Shielding materials and potential Radar Absorption Materials.

In this work we investigate impact of intentional electromagnetic interference (IEMI) on sensors of an unmanned aerial vehicle (UAV). The UAV under test is a small, commercial off-the-shelf quadcopter. IEMI is applied in the form of a narrowband high-power electromagnetic (HPEM) pulse characterized by frequencies between 100 MHz and 3.4 GHz and field strengths above the immunity levels required by electromagnetic compatibility (EMC) standards. The tests are conducted in a shielded hall with the UAV immobilized during the tests. We report results of real-time observations of the UAV behaviour under HPEM influence complemented by the analysis of the flight record data extracted from the UAV logs.

Enhanced Electromagnetic Absorption of Cement Composites by Controlling the Effective Cross-sectional Area of MXene Flakes with Diffuse Reflection Based on Carbon Fibers

Stretchable electromagnetic interference (EMI) shields with strain-insensitive EMI shielding and Joule heating performances are highly desirable to be integrated with wearable electronics. To explore the possibility of applying geometric design in elastomeric liquid metal (LM) composites and fully investigate the influence of LM geometry on stretchable EMI shielding and Joule heating, multifunctional wrinkle-structured LM/Ecoflex sandwich films with excellent stretchability are developed. The denser LM wrinkle enables not only better electrical conduction, higher shielding effectiveness (SE) and steady-state temperature, but also enhanced strain-stable far-field/near-field shielding performance and Joule-heating capability. More strikingly, compared to most previously reported stretchable EMI shields or electric heaters, the densely wrinkled film could achieve multidirectional strain-insensitive shielding behavior with slightly strain-enhanced or strain-invariant EMI SE under stretching parallel or perpendicular to the electric field of EM waves, as well as show ideal strain-insensitive Joule-heating behavior over a larger strain range of 250%. The current findings suggest an effective strategy for developing stretchable LM-based composites with strain-insensitive properties.

Biomass-based honeycomb-like architectures for preparation of robust carbon foams with high electromagnetic interference shielding performance

Impact of micro-cracking and self-healing on electromagnetic interference shielding of ultra-lightweight engineered cementitious composites

Electromagnetic interference shielding performance of lightweight NiFe2O4/rGO nanocomposite in X- band frequency range

Natural fiber and aluminum sheet hybrid composites for high electromagnetic interference shielding performance