Low Reflection Coefficient Research Articles

Zeolitic Imidazolate Frameworks Derived Magnetic Nanocage/MXene/Nanocellulose Bilayer Aerogels for Low Reflection Electromagnetic Interference Shielding and Light‐to‐Heat Conversion

AbstractTo cope with the increasingly serious electromagnetic pollution, the demand for electromagnetic interference (EMI) shielding materials with low electromagnetic wave reflection ability has become urgent. Controlling electrical components, magnetic components, and designing the EMI material structure can effectively improve electromagnetic shielding performance, but this remains a significant challenge. Besides, extreme cold weather conditions also do considerable potential damage to the normal work of outdoor electronic equipment. Integrated light‐to‐heat conversion capability on electromagnetic shielding materials can further improve the stability and reliability of the equipment. Herein, the novel bilayer aerogels composed of zeolitic imidazolate frameworks derived hollow CoNi carbon nanocage/MXene Ti3C2Tx/nanocellulose (BZMN) are prepared by a two‐step freezing method. BZMN aerogels exhibit good EMI shielding effectiveness (SE) with low reflection coefficient (R coefficients): 35.1 dB (R coefficient = 0.28) and 21.2 dB (R coefficient = 0.25). The unique structures of bilayer aerogels demonstrate the ability to absorb more electromagnetic waves through interfacial polarization and multiple scattering. The green shielding index (gs) of BZMN aerogels can reach 2.88. Moreover, BZMN aerogels show remarkable and unique light‐to‐heat conversion performance on different surfaces. Under 2.0 sun intensity, temperatures can reach 109.3 °C in the upper layer and 102.3 °C in the lower layer. Under 0.8 W cm−2 near‐infrared (NIR) laser intensity, the temperatures can rise to 234.1 °C in the upper layer and 167.4 °C in the lower layer. In addition, the size and shape of BZMN aerogels can be customized according to the mold. These features present BZMN aerogels as advanced potential low reflection EMI shielding device candidates, useful for future telecommunication and electronic equipment protection.

Customizable gradient MXene/polyurethane modules for electromagnetic interference shielding with low reflection and thermal management

The conductive polymer composites (CPC) with elevated levels of conductivity typically exhibit enhanced electromagnetic interference shielding effectiveness (EMI SE), however, this enhancement is often paralleled by an augmented risk of secondary electromagnetic (EM) pollution, attributable to the increased EM reflection. Developing a facile method to construct an eco-friendly CPC for EMI shielding that simultaneously exhibits low reflection and high shielding performance remains a promising yet challenging pursuit. Moreover, excellent shielding materials should possess exceptional thermal management capabilities to protect individuals or equipment under extreme conditions. Herein, we have engineered the MXene/polyurethane (MXene/PU) sponge (MPS) modules characterized by the hierarchical porous structure. Through the strategic modular combination of impedance-matching and impedance-mismatching modules tailored for different application contexts, the customizable gradient MXene/PU sponge (GMPS) facilitates achieving a balance of exceptional average EMI SE (44.6 dB), a low reflection coefficient (R = 0.18), and superior photo/electrothermal conversion capability. Furthermore, both experimental results and finite element analyses are adopted to explore the effect of the arrangement order of GMPS on EMI shielding performance. Leveraging the green, health-conscious, and flexibly customizable approach, it manifests tremendous potential across various areas, including intelligent residences and multifunctional integrated systems.

Tuning the essential physical properties of KTaO3 through sulfur, selenium doping, and oxygen vacancy: A first principle investigation

The objective of this work is to use density functional theory (DFT) analysis to explain the effects of sulfur (S), selenium (Se), and oxygen vacancies on the mechanical, electrical, optical, dynamical, and thermoelectric properties of KTaO3. Our investigation has uncovered important modifications to KTaO3 many characteristics, most notably to its band gap values. Crucially, every chemical that was studied showed evidence of both dynamical and mechanical stability. These compounds are also good prospects for a variety of optoelectronic applications due to their promising optical properties, which include strong optical conductivity throughout the visible spectrum, low reflection, and high absorption coefficients. Our thorough analysis has shown the remarkable electrical, optical, and mechanical characteristics, including high absorptivity, low reflectivity, hardness, ductility, and semiconducting behavior. It has also highlighted the stability of all computed phases. The optical characteristics and adjusted band gap of KTaO3 indicate that it has substantial potential for use in solar cells, providing avenues for improving the efficiency of solar energy conversion. In addition, the exceptional heat conductivity of KTaO3 offers exciting opportunities for its use as a heat sink material.

Cellulose–derived carbon scaffolds with bidirectional gradient Fe3O4 distribution: Integration of green EMI shielding and thermal management

Cellulose papers (CPs) possess a pore structure, rendering them ideal precursors for carbon scaffolds because of their renewability. However, achieving a tradeoff between high electromagnetic shielding effectiveness and low reflection coefficient poses a tremendous challenge for CP-based carbon scaffolds. To meet the challenge, leveraging the synergistic effect of gravity and evaporation dynamics, laminar CP-based carbon scaffolds with a bidirectional gradient distribution of Fe3O4 nanoparticles were fabricated via immersion, drying, and carbonization processes. The resulting carbon scaffold, owing to the bidirectional gradient structure of magnetic nanoparticles and unique laminar arrangement, exhibited excellent in-plane electrical conductivity (96.3 S/m), superior electromagnetic shielding efficiency (1805.9 dB/cm2 g), low reflection coefficients (0.23), and a high green index (gs, 3.38), suggesting its green shielding capabilities. Furthermore, the laminar structure conferred upon the resultant carbon scaffold a surprisingly anisotropic thermal conductivity, with an in-plane thermal conductivity of 1.73 W/m K compared to a through-plane value of only 0.07 W/m K, confirming the integration of thermal insulation and thermal management functionalities. These green electromagnetic interference shielding materials, coupled with thermal insulation and thermal management properties, hold promising prospects for applications in sensitive devices.

LH launchers for tokamaks at IPR

Earlier, a conventional grill launcher-based LHCD system has been developed to drive plasma current non-inductively in tokamaks at IPR (ADITYA and SST1) at a frequency (fo = ωo/2π) of 3.7 GHz, which has the ability to launch pure spectrum with high directivity. Grill having large number of sub-waveguides launches a sharp spectrum, which drive LH current more efficiently and therefore was preferred for carrying out plasma physics studies in a controlled manner. An over-dense plasma near the mouth of the launcher provides good coupling of LHWs with plasma and therefore the grill launcher needs to be placed close to the last close flux surface (LCFS). The grill launcher at IPR allows to launch LHWs having a parallel refractive index (N||) from 1.5 to 4.0 by varying the phase difference between adjacent sub-waveguides from 60° to 160°. For ADITYA tokamak, owing to space constraints, the grill launcher with eight sub-waveguides (arranged in two rows, each having four sub-waveguides) could be developed to launch of power up to 120 kW, and therefore, the topology of the ADITYA LHCD was not very complex. However, for the 1 MW LHCD system for SST1 tokamak, the grill launcher with sixty-four sub-waveguides (arranged in two rows, each having thirty-two sub-waveguides) was developed and the SST1 LHCD system, thus conceived, was huge and very complex offering tremendous engineering design challenges. For reactor-grade plasmas, where rf power of a few tens of MW would be launched in to the plasmas, a more compact and reactor-relevant LH launcher, often known as passive–active multijunction (PAM) is foreseen. The PAM launcher offers very good coupling with low reflection co-efficient (∼2–5%) when the plasma density near the mouth of the launcher is near cutoff densities for a given frequency (ωo = ωpe, the electron plasma frequency), and thus allowing it to be placed far away from the LCFS of the plasma, thereby minimizing deleterious effects on launcher due to hostile edge plasma conditions and makes this launcher relevant for reactor-grade plasmas. Further, the space behind the passive waveguide can be utilized for neutron shielding and efficient thermal management. On the contrary, it offers reduced directivity and the spectrum can be varied over a narrow range. Further, the network of transmission lines feeding this launcher is relatively simpler and offers less technological challenges. Thus, 250-kW PAM launcher (comprising of two modules)-based LHCD system for ADITYA-U tokamak has been designed and developed. The launched N|| may be varied over a narrow range (2.25 ± 0.375) by varying the phase difference between adjacent modules over 180° ± 90°. The physics requirements, design philosophy, engineering challenges/solutions, the key outcome and achievements as we embark on to PAM launcher are presented and discussed. Based on our experience of PAM launcher, for ADITYA-U tokamak, conceptual design of the PAM launcher for SST1 is also presented.

Multifunctional asymmetric foam with Compression-Enhanced EMI shielding effectiveness exhibits Real-Time tunability of Reflection/Absorption ratio and pressure sensing

Traditional electromagnetic interference (EMI) shielding materials usually have constant shielding effectiveness and fixed absorption/reflection ratio, and cannot respond to the real-time changing shielding requirements of smart wearable electronic devices. Herein, smart asymmetric foams (AF) composed of chromium dioxide decorated graphene (CrO2@G)/thermoplastic polyurethane-poly vinyl alcohol (TP) foams and a eutectic gallium-indium liquid metal (LM)/TP layer were developed via an efficient ‘split conductive modular design/assembly’ strategy. The AF with compressive stress-controlled conductivity can capture and attenuate electromagnetic (EM) waves in the form of absorption-dominated or reflection-dominated by adjusting the compressive strain in real time. The optimized AF achieved a low average reflection coefficient (R) of 0.12 and a minimum value of 0.05, holding the lowest record for LM-based EMI shielding materials with comparable SEt. As the compressive strain increases from 0 to 90 %, the AF alter its SEt from 63.8 ± 3 dB to 92.7 ± 2 dB, while reducing the average EM wave absorption efficiency from 88 % to 39 %, allowing it to be adjusted in real time as needed to block EM waves. Furthermore, the AF demonstrated its application as a strain sensor to monitor human motions. This work provides an effective strategy for the design and preparation of multifunctional smart EMI shielding materials.

Multiband circularly-polarized stacked elliptical patch antenna with eye-shaped slot for GNSS applications

Abstract This paper introduces a tri-band stacked elliptical patch antenna featuring a right-handed circular polarized, designed to operate at the L2, L5, and L1 Global Navigation Satellite System bands. Initially, an elliptic patch is constructed and fed by a probe feed to generate TM110 and TM210 modes at resonance frequencies calculated using Mathieu functions. The probe position is precisely adjusted to excite the quasi-orthogonal mode of TM110 to generate circularly polarized (CP) waves at the L2 and L5 bands. Subsequently, an eye-shaped aperture is engraved into the elliptical patch to enhance the axial ratio (AR) beamwidth in the L2 and L5 bands and stimulate the orthogonal mode of TM210 to produce CP waves at the L1 band. Lastly, a stacked partially elliptical parasitic element is placed beneath the upper slotted elliptical patch to enhance the orthogonality of TM210 surface current versions and thus improve the AR beamwidth at the L1 band. The proposed antenna shows low reflection coefficient values at 1.12–1.33 (L2/L5), and 1.5–1.66 GHz (L1). The AR beamwidths are 133/213∘, 167/163∘, and 36/103∘ at two orthogonal cutplanes at L5, L2, and L1 bands, respectively. The antenna also has decent gains of 6–6.9 dBic across the three bands.

Unveiling the optical, electrical, and thermodynamic properties of γ-(Cs, Rb)PbBr3

The all-inorganic perovskite CsPbBr3 has garnered significant attention in the fields of optoelectronic devices owing to its favorable bandgap. However, CsPbBr3 undergoes polymorphic phase transitions, existing in three light-active phases: Pbnm (γ), P4/mbm (β), and Pm-3m (α). Although extensive investigations have been conducted on the α-phase, the room-temperature γ-phase has received limited investigation. The present work explores the thermodynamic properties and optoelectronic characteristics of the (Cs, Rb)PbBr3 perovskite system by means of a combinatorial density-functional-theory (DFT) and CALPHAD method. An increase in Rb doping of CsPbBr3 induces structural distortion of γ-phase, resulting in a widened bandgap from 2.12 eV to 2.28 eV. The bandgap increase will eventually lead to changes in optical properties, such as poor absorptivity and energy consumption under high Rb doping. Moderate doping enables (Cs, Rb)PbBr3 to retain the excellent optical properties and energy consumption of CsPbBr3. Especially when Rb doping is 0.25, the solid solution has the lowest reflection coefficient. The thermodynamic phase diagram shows that the solid solution (Cs, Rb)PbBr3 maintains excellent thermodynamic stability. In addition, the phase diagram quantifies the temperature range of the γ-phase, α-phase, and coexistence of two phases, which provides the theoretical guidance for the preparation of (Cs, Rb)PbBr3 solid solution films in the future.

Optical characteristics of structures with silicon nanowires and metal nanoparticles

To calculate the optical parameters, the finite difference method in the time domain (FDTD) was used, which can be applied to solve Maxwell’s equations. A large number of combinations of a planar structure with metal nanoparticles and a structure with nanowires and metal nanoparticles (NPs) were calculated. The height of nanowires h varied from 50 to 3000 nm, the period of the structure P was 100–600 nm, and the diameter of metal nanoparticles d was 50–400 nm. The reduction of light reflection was determined by the anti-reflection effect of the Si-NWs array itself and the direct scattering effect of metal nanoparticles. It was shown that all structures gave significantly lower reflection coefficients compared to that of a solid silicon plate.

Computational Design of a Broadband In-Line Coaxial-to-Rectangular Waveguide Transition

This Communication presents a computational design approach for a broadband in-line coaxial-to-rectangular waveguide transition having a 2.83:1 bandwidth. Existing designs have a bandwidth ranging from 1.36:1 to 2:1. The proposed transition consists of a four-step ridge transformer and three sections of the rectangular waveguide. The proposed design approach extends the bandwidth of the transition by a theory-based design of the width and height of the three-section waveguides and by a computer-aided optimization of the stepped-ridge transformer. The dimensions of the three waveguide sections are determined such that the transition operates from very close to the TE10-mode cutoff to slightly less than the TE30-mode cutoff. A four-step ridge transformer was computer-optimized for a low reflection coefficient over a broad bandwidth. The proposed design approach was applied to the design of a coaxial-to-WR75 transition whose reflection coefficient is less than −22.6 dB at 8.14–23.00 GHz (2.83:1 bandwidth). The dimensions of the proposed transition were obtained using an electromagnetic simulation tool. The increased bandwidth of the transition can be very useful, especially in measurement applications.

THz Microstrip Antenna for Terabit Wireless Local Area Networks

In order to replace millimetre wave communication for extremely fast terabit wireless local and personal area network connectivity, researchers have been looking into the possibilities of the terahertz band for establishing wireless data communication at terabit rates. The IEEE 802.15 WPAN Terahertz Interest Group (IGTHz) has been created to encourage research in the terahertz bands and set standards for their use, in order to facilitate progress and advancement in this area. The specific objective of this study is to design and analyze a microstrip antenna working at 3.5 THz resonant frequency. The proposed novel antenna includes three layers: a top layer that represents the patch, a second layer that represents the substrate, and a bottom layer that represents the ground plane. It is designed using a 32 nm thin FR-4 substrate with a permittivity of 4.4. Using HFSS simulations, it was found that the proposed antenna has an overall efficiency greater than 85% within the working frequency range of 3.5 THz. Additionally, it exhibited an extremely low reflection coefficient (S11) of -43.61 dB at 3.5 THz, with an efficiency exceeding 80%. This simple and broadband antenna design could have relevance in high-speed data transmission networks.

Anisotropic properties of two-dimensional (2D) tin dihalide (SnX2, X = Cl, Br, I) monolayer binary materials

This paper investigated the electronic properties and photoresponse of two-dimensional SnX2 (X = Cl, Br, I) monolayer binary materials using computational techniques. The calculated band structure and density of states indicate that these are large band gap semiconducting materials with an indirect band gap. The studied chemical bonding mechanism shows the existence of the hybrid bonding of ionic and covalent bonds in these dihalide materials. The valence band (VB) and conduction band (CB) edge positions are also estimated, using the concept of electronegativity and band gap, to investigate the photocatalytic activity of SnX2. Next, we investigated the polarization and energy-dependent dielectric and optical functions along the crystallographic axes of these materials in the linear response approach of the perturbing incident oscillating light field. These materials exhibit an anisotropic behavior of these functions, especially in the high-energy visible and low-energy ultraviolet (UV) regions. The absorption of incident light photons is very fast in SnI2 than SnBr2 and SnCl2 in the low-energy UV region. It demonstrates the higher absorption coefficient and optical conductivity in Snl2. The obtained average static refractive index of SnCl2 is comparable to that of glass (1.5), showing its application as transparent material. The low reflection coefficient, less than 20%, makes them superior for antireflection coating materials in the infrared and visible regions. The prominent energy loss peaks show the existence of plasmon resonances in these materials. The most of losses occur in the UV region. The investigated electronic and photoresponse properties indicate that these Sn-based dihalide materials are excellent for electronic devices and optoelectronic applications. Also, the calculated VB and CB edge positions with respect to the normal hydrogen electrode show the favorable water-splitting capability of these materials.

Magnetic/conductive biochar frames derived from Fe3O4-coated loofah sponges for green electromagnetic interference shielding application

Several biochar frame electromagnetic interference shielding composites have been developed; however, integrating high shielding effectiveness (SE) and low reflection coefficient ([Formula: see text]) into biochar frames with excellent electrical conductivity have proven to be a great challenge. Herein, because of the abundant groups on the surface of the intricate fibers of the loofah sponge, it absorbed many iron ions, which can form a Fe3O4 coating when they react with hydroxyl groups. After carbonization, the Fe3O4 coating still tightly held the carbonized fibers in a porous structure, forming a biochar frame with consecutive magnetic/conductive interfaces. Furthermore, the incorporation of a Fe3O4 coating did not negatively affect the electrical conductivity of the composites obtained ([Formula: see text]21 S/m) but instead endowed the composites with good magnetic properties. The resultant composites had an SE, specific SE, [Formula: see text] and green index ([Formula: see text]) of 47.2 dB, 363 dB/cm, 0.089, and 10.2, respectively, which were better than those of previously reported biochar-based shielding materials. The synergistic effect of the three-dimensional carbon frame, magnetic coating, and porous structure is responsible for excellent green shielding abilities.

High Gain WAT Antenna for 38 GHz 5G Systems

The article presents a high gain WAT microstrip antenna designed for 5G communication systems operating in the 38 GHz band. The antenna concerned has a compact structure with dimensions of 5.16×5.05 mm. Rogers RT5880 laminate with a dielectric coefficient of 2.2 and a thickness of 0.254 mm was used as its substrate. The antenna works at a center frequency of 38 GHz and is characterized by a low reflection coefficient of -29.11 dB, a high energy gain of 7.61 dB and a wide operating band of 1.21 GHz (3.18%). The paper presents an analysis of the simulation results and measurements of the device's electrical parameters and radiation patterns.

Bio-inspired flexible versatile textiles for excellent absorption-dominated electromagnetic interference shielding, thermal management, and strain sensing

Multifunctional flexible textiles are urgently required for wearable electronics and military equipment. However, it remains a big challenge for them to achieve absorption-dominated electromagnetic interference (EMI) shielding and maintain excellent multifunctionalities. Herein, inspired by hierarchical structure of muscle, a novel multilayer self-assembly strategy was proposed to conformally deposit conductive substances and absorption fillers on flexible textiles to realize superior versatility in EMI shielding, thermal management, and strain sensing. The formed muscle-like nanostructure was composed of Ag nanoparticles, Ag nanowires, MXene, and FeCo-C. Benefiting from the 3D cross-linked stable networks with high conductivity (14075.3 S·m−1), durable EMI shielding (85 dB after stretching and bending), and excellent electrical heating (116.3 °C under 1.8 V) were achieved. Based on robust electrostatic interaction between FeCo-C and MXene, strong EMW absorption was realized with a low reflection coefficient (0.168). The textile also demonstrated excellent strain sensing performance in a linear range of 5–60 % with a fast response time (121 ms) for complex motion detection. Besides, the textiles had good gas permeability, ensuring long-term wearable comfortability. This work offers a significant paradigm to construct multifunctional flexible textiles for next-generation integrated flexible electronic devices and military equipment with practical applications.

Мodel of diffraction of electromagnetic waves on explosive objects

A model of electromagnetic wave diffraction on an explosive object without metal structural substances is proposed. The properties of the materials of the most common anti-personnel mines were analyzed and it was established that their shell is dielectric, and explosive substances are divided into two groups depending on their dipole moment. In particular, the explosive substances such as hexogen, pentaerythritol tetranitrate, and mercury fulminate with zero dipole moment and according to their electromagnetic properties, they belong to ideal dielectrics. The explosives trinitrotoluene, tetryl, lead trinitroresorcinate, and lead azide should be considered as low-loss dielectrics. An electrodynamic model was built to calculate the reflection coefficients and the passage of electromagnetic plane waves of the microwave range through the multilayer structure of an explosive object. To determine the equivalent wave resistance of the multilayer structure of an explosive object, the use of the theory of long lines is proposed. It is established that for microwave radiation, the layers of the case of explosive objects made of dielectric substances can be neglected due to their small thickness. The modeling results show that most anti-personnel mines have a low reflection coefficient, which makes them difficult to detect, but at the same time increases the amount of energy that can pass deep into the body of the explosive substance. It has been shown that explosive objects with dipole explosive substances are capable of absorbing electromagnetic radiation energy. The obtained results allow us to qualitatively assess the susceptibility of explosive substances to their remote detonation by irradiation with powerful pulses of electromagnetic radiation in the microwave range.

Ultra-Low Loading of Ultra-Small Fe3 O4 Nanoparticles on Nonmodified CNTs to Improve Green EMI Shielding Capability of Rubber Composites.

From a material design perspective, the incorporation of Fe3 O4 @carbon nanotube (Fe3 O4 @CNT) hybrids is an effective approach for reconciling the contradictions of high shielding and low reflection coefficients, enabling the fabrication of green shielding materials and reducing the secondary electromagnetic wave pollution. However, the installation of Fe3 O4 nanoparticles on nonmodified and nondestructive CNT walls remains a formidable challenge. Herein, a novel strategy for fabricating the above-mentioned Fe3 O4 @CNTs and subsequently assembling segregated Fe3 O4 @CNT networks in natural rubber (NR) matrices is proposed. The advanced and unique structure, magnetism, and lossless conductivity endow the as-obtained Fe3 O4 @CNT/NR with a shielding effectiveness (SE) of 63.8dB and a low reflection coefficient of 0.24, which indicates a prominent green-shielding capability that surpasses those of previously reported green-shielding materials. Moreover, the specific SE reaches 531dB cm-1 , exceeding that of those of previously reported carbon/polymer composites. Meanwhile, the outstanding conductivity enables the composite to reach a saturation temperature of ≈95°C at a driving voltage of 1.5V with long-term stability. Therefore, the as-fabricated Fe3 O4 @CNT/rubber composites represent an important development in green-shielding materials that are applied in cold environment.

Bidirectional periodic pore structure Si-C-N multiphase ceramic with high thermostability and excellent microwave absorption properties over a wide temperature range

High-temperature electromagnetic wave (EMW) absorption materials are urgently needed for high thrust-to-weight ratio aero-engine. A novel EMW absorbing Si-C-N ceramic at elevated temperatures was fabricated by chemical vapor infiltration (CVI) Si3N4 and SiC on 2D plain carbon fiber preform forming periodic framing and then oxidation to remove carbon fiber. The three-level gradient periodic microstructure was in-situ constructed in the Si-C-N ceramics to meet the impedance matching characteristics and effectively attenuate as much as EMWs. Compared with traditional EMW absorption materials, the Si-C-N ceramics with bidirectional periodic pore had a lower density of 1.2 g/cm3 and better frequency dispersion behavior which could obtain an effective absorption bandwidth (EAB) covering the whole X-band at 2.45 mm and the lowest reflection coefficient (RCmin) of − 40 dB at 3.5 mm. The optimal Si-C-N ceramics (S2) show excellent EMW absorption performance over a wide temperature range. The Si-C-N ceramic had a promising applications at high temperatures.

Research on the SAW Gyroscopic Effect in a Double-Layer Substrate Structure Incorporating Non-Piezoelectric Materials.

The SAW (surface acoustic wave) gyroscopic effect is a key parameter that reflects the sensitivity performance of SAW angular velocity sensors. This study found that adding a layer of non-piezoelectric material with a lower reflection coefficient than that of the upper-layer material below the piezoelectric substrate to form a double-layer structure significantly enhanced the SAW gyroscopic effect, and the smaller the reflection coefficient of the lower-layer material, the stronger the SAW gyroscopic effect, with values being reached that were two to three times those with single-layer substrate structures. This was confirmed using a three-dimensional model, and the experimental results also showed that the thickness of the piezoelectric layer and the type of the lower-layer material also had a significant impact on the SAW gyroscopic effect. This novel discovery will pave the way for the future development of SAW angular velocity sensors.

Shielding Effectiveness of Unmanned Aerial Vehicle Electronics with Graphene-Based Absorber

Within this study, we explored the augmented security measures for the electronics of unmanned aerial vehicles (UAVs) within an RF environment. UAVs are commonly utilised across various sectors, and their use as auxiliary platforms for cellular networks, as parallel networks working in tandem with ground-based base stations, holds considerable promise. In this context, ensuring the uninterrupted operation of UAVs is a paramount objective. However, the considerable external electromagnetic interference emitted by existing base stations may jeopardise the functionality of UAV electronics. This could potentially lead to an unintended flight path and a sudden cessation of communication with the operator. To mitigate the detrimental impact of the RF field, we advocate covering the UAV casing with reduced graphene oxide (RGO). The efficacy of RGO’s shielding effectiveness (SE) was investigated over a frequency spectrum from 100 MHz to 10 GHz. Our scrutiny of this property was centred around the measurement of scattering matrix coefficients of the unadulterated material—without additives of any kind. Our findings show that this material is a favourable candidate for UAV absorbers due to its low reflection coefficient coupled with its high absorption capacity. The studied absorber ensures an SE value of 25 dB and 30 dB for a 3 mm layer at frequencies of 3.6 GHz (pertaining to the 5G system) and 5.8 GHz (pertaining to LTE), respectively.