Strong Electromagnetic Wave Research Articles

Biomimetic Multi-Interface Design of Raspberry-like Absorbent: Gd-doped FeNi3@Covalent Organic Framework Derivatives for Efficient Electromagnetic Attenuation.

Structural design and interface regulation are useful strategies for achieving strong electromagnetic wave absorption (EMWA) and broad effective absorption bandwidth (EAB). Herein, a monomer-mediated strategy is employed to control the growth of covalent organic framework (COF) wrapping flower-shaped Gd-doped FeNi3 (GFN), and a novel raspberry-like absorbent based on biomimetic design is fabricated by thermal catalysis. Further, a unique dielectric-magnetic synergistic system is constructed by utilizing the COF-derived nitrogen-doped porous carbon (NPC) as the shell and anisotropic GFN as the core. The electromagnetic parameters of the GFN@NPC composites can be tuned by adjusting the proportions of GFN and NPC. Off-axis electron holography results further clarify the interface polarization and microscale magnetic interactions affecting the EMW loss mechanism. As a result, the GFN@NPC samples exhibit broad EMWA performance. The EAB values of all GFN@NPC composites reach up to 6.0 GHz, with the GFN@NPC-2 sample showing a minimum reflection loss (RLmin) of -69.6 dB at 1.68 mm. In addition, GFN@NPC-2 achieves a maximum radar cross-section (RCS) reduction of 29.75 dB·m2. A multi-layer gradient structure is also constructed using metamaterial simulation to achieve an ultra-wide EAB of 12.24 GHz. Overall, this work provides a novel bio-inspired design strategy to develop high-performance EMWA materials.

Structural modification of mesoporous lanthanum oxide into 3D coral-like and nano needle-like structure for effective broadband microwave absorbing materials☆

Structural modification of three dimensional (3D) materials for the application of dielectric loss-based microwave absorbing materials (MAMs) usually relies on intricate synthesis process and can pose challenges in terms of scalability and mass production for practical application. In this work, we reported a successful attempt in modifying the 3D structure of mesoporous lanthanum oxide (La2O3) for effective broadband MAMs candidate via simple co-precipitation process. The inclusion of cetyl-trimethylammonium bromide (CTAB) and hydrothermal aging treatment result in a significant transformation of La2O3 particles from their original polygonal form to a 3D coral-like and nano needle-like structure. The utilization of CTAB and hydrothermal aging results in the increase of surface area and a two-fold increase in pore volume of the resulting La2O3. Due to its unique 3D structure, the 3D coral-like and nano needle-like La2O3 materials possess a broadband electromagnetic (EM) wave absorption characteristic with the effective absorption bandwidth (EAB) covering the C-band frequency range. Specifically, in the La2O3 C-H sample (with CTAB – with hydrothermal), it exhibits strong EM wave absorption with a reflection loss (RL) value of –33.07 dB which equals to 99.95% EM wave absorption at a thickness of only 1.50 mm. The detailed analysis of EM wave absorption properties reveals that the improvement of La2O3 materials to attenuate EM wave energy arises from the dielectric loss phenomenon, the enhanced interfacial polarization, multiple reflections mechanism, and conduction loss mechanism induced by the 3D structural formation of the La2O3 structure. This work proposes a novel and efficient approach in synthesizing and modifying 3D materials for effective broadband EM wave absorption.

Synergistically magnetic and dielectric properties of two dimensional Fe3Al@PPy lamellae exhibiting broadband and strong electromagnetic wave absorption

Addressing the issue of low impedance characteristics is essential to improve the electromagnetic wave absorption performance of magnetic materials. Herein, two dimensional Fe3Al@polypyrrole (PPy) lamellae with synergistic magnetic and dielectric properties are fabricated by a mechanical alloying, ordering transformation and polymerization process, which exhibits excellent electromagnetic wave absorption performance. By carefully controlling the thickness of the PPy shell, the optimized Fe3Al@PPy lamellae show a minimum reflection loss of −45.6 dB and an effective absorption bandwidth of 9.1 GHz at a thickness of only 1.5 mm. The conformal growth of Fe3Al@PPy lamellae can induce strong interfacial polarization, dipole polarization, multiple scattering effect and magnetic loss behaviors for the attenuation of electromagnetic waves. This study demonstrates a facile strategy for the development of efficient Fe3Al@PPy composite absorbents showing great potential for practical applications.

Coherent radiation of an electron bunch colliding with an intense laser pulse

We study the conditions for coherent radiation of an electron bunch driven by a counterpropagating strong pulsed electromagnetic plane wave. We derive the spectrum of the coherent radiation and show that it is emitted backward with respect to the laser propagation direction and has a very narrow angular spread. We demonstrate that for a solid density plasma coherent radiation extends to frequencies up to hundreds of keV, thereby enhancing the low-frequency part of the spectrum by many orders of magnitude. Our analytical findings are tested with three-dimensional particle-in-cell simulations of an electron bunch passing through a laser pulse, clearly demonstrating how the coherence can essentially modify the observed radiation spectrum. Published by the American Physical Society 2024

Hollow engineering in CoNi@Air@C@MoS2 multicomponent composites derived from bimetallic CoNi Prussian blue analogs for ultra-wide bandwidth and strong electromagnetic wave absorption

In recent years, two-dimensional layered transition metal dichalcogenides-based multicomponent composites (MCCs) acting as electromagnetic wave (EMW) materials have received intensive investigations. However, the vulcanication of metal greatly hindered their enhancement of EMW absorption performances (EMWAPs). Herein, a combined metal-organic frameworks-derived and hydrothermal strategy was presented to produce yolk-shell structure (YSS) CoNi@Air@C@MoS2 MCCs. The results showed that the thermal and hydrothermal treatments resulted in the generation of YSS and two-dimensional MoS2 nanosheets, which maintained the original morphology of CoNi Prussian blue analogues. The protection of thick C layer well inhibited the vulcanization of inner CoNi alloy. The formed sheet-like MoS2 further optimized impedance matching characteristics, which led to the satisfactory EMWAPs of CoNi@Air@C@MoS2 MCCs. Furthermore, the EMWAPs could be further improved by optimizing the Ni:Co atom ratios CoNi@Air@C@MoS2 MCCs, which stemmed from their boosted impedance matching performances, EMW attention and polarization loss abilities. The absorption bandwidth and reflection loss values for YSS CoNi@Air@C@MoS2 MCCs are 8 GHz and −60.83 dB, which covered almost all C-Ku bands. In general, our research work provided a valid strategy to produce YSS magnetic CoNi@Air@C@MoS2 MCCs with high efficiency, which well avoided the vulcanization of metal nanoparticles, made best of hollow engineering and atomic ratio optimization strategy to boost the comprehensive EMWAPs.

Generation of Narrow Beams of Super High-Energy Gamma Quanta in the Resonant Compton Effect in the Field of a Strong X-ray Wave

The article presents a theoretical study of Oleinik resonances in the process of scattering a gamma quantum by an ultrarelativistic electron in the field of a strong electromagnetic wave with intensities up to 1027Wcm−2. The resonant kinematics for three possible resonant reaction channels in a strong external field have been studied in detail. It is shown that under resonant conditions, the scattering channels of the reaction effectively split into two first-order processes according to the fine structure constant, such as the external field-stimulated Compton effect. The annihilation channel of the reaction effectively decays into direct and reverse the external field-stimulated Breit–Wheeler processes. In the absence of interference from the reaction channels, a resonant differential cross-section was obtained in a strong external electromagnetic field. The cases when the energy of the initial electrons significantly exceeds the energy of the initial gamma quanta have been studied. At the same time, all particles (initial and final) fly in a narrow cone away from the direction of wave propagation. The conditions under which the energy of ultrarelativistic initial electrons is converted into the energy of a finite gamma quantum are studied. It is shown that the resonant differential cross-section of such a process significantly (by several orders of magnitude) exceeds the corresponding nonresonant cross-section. This theoretical study predicts a number of new physical effects that may explain the high-energy fluxes of gamma quanta produced near neutron stars and magnetars.

The Impact of a Strong Electromagnetic Wave on the Quantum Hall Effect in Cylindrical Quantum Wires

The impact of strong electromagnetic waves Hall effect is studied theoretically in a Cylindrical Quantum Wire (CQW) with infinitely high potential inside the wire and elsewhere subjected to a dc electric field , a magnetic field and a laser radiation . By using the quantum kinetic equation method for electrons interacting with Acoustic Phonon (AP) at low temperatures, we obtain analytical expressions for the conductivity tensor and the Hall Coefficient (HC), which are different from in comparison to those obtained for a rectangular quantum wire (RQW) or two-dimensional (2D) electron systems. Numerical calculations are also applied for GaAs/GaAsAl CQW to show the nonlinear dependence of the HC on the electromagnetic wave (EMW) frequency, and the radius, the length characteristic parameters of CQW. Wave function and energy spectrum in a CQW are dissiminar to those in Quantum Wires (QWs). Therefore, all numerical results are different from those in the case of QWs. The most important result is that the HC reaches saturation as the radius, the length of CQW or the EMW frequency increases.

Biomimetic Leaf-Vein Aerogel for Electromagnetic Wave Absorption and Thermal Superinsulation.

Electromagnetic protection in extreme environments requires materials with excellent thermal insulation capability and mechanical property to withstand severe temperature fluctuations and complex external stresses. Achieving strong electromagnetic wave absorption (EMA) while sustaining these exceptional properties remains a significant challenge. Herein, a facile approach is demonstrated to fabricate a biomimetic leaf-vein MXene/CNTs/PI (MCP) aerogel with parallel venations through bidirectional freeze-casting method. Due to its multi-arch lamellar structure and parallel venations within the aerogel layers, the ultralight MCP aerogel (16.9 mg·cm-3) achieves a minimum reflection loss (RLmin) of -75.8dB and a maximum effective absorption bandwidth (EABmax) of 7.14GHz with an absorber content of only 2.4wt%, which also exhibits superelasticity and structural stability over a wide temperature range from -196 to 400°C. Moreover, this unique structure facilitates rapid heat dissipation within the layers, while significantly impeding heat transfer between adjacent layers, achieving an ultralow thermal conductivity of 15.3 mW·m-1·K-1 for thermal superinsulation. The combination of excellent EMA performance, robust structural stability, and thermal superinsulation provides a potential design scheme under extreme conditions, especially in aerospace applications.

Multi-heterointerface integration in nitrogen-doped Ti3C2Tx@Fe3O4 nanocomposites for superior microwave absorption

Engineering a lightweight and thin microwave absorber through the design of multiple heterogeneous interfaces represents a significant challenge. Here, we synthesized a nitrogen (N)-doped Ti3C2Tx@Fe3O4 (N–Ti3C2Tx@Fe3O4) nanocomposite with a sandwich-like structure through a solvothermal approach using hydrazine hydrate as the N donor. The numerous Ti3C2Tx electron transfer pathways of Ti3C2Tx enable the realization of a hierarchical conduction network within N–Ti3C2Tx@Fe3O4. The introduction of defects through N doping and the integration of Fe3O4 with Ti3C2Tx are pivotal for enhancing the dipole polarization. The heterogeneous interfaces in N–Ti3C2Tx@Fe3O4, coupled with Fe3O4 components, substantially boost the electromagnetic wave (EMW) absorption performance of the composite. An optimal N integration and the loading of Fe3O4 in Ti3C2Tx result in an improved impedance matching of N–Ti3C2Tx@Fe3O4. The synergistic effect of the improved impedance matching and the strong EMW attenuation capability endow N–Ti3C2Tx@Fe3O4 with enhanced microwave absorption (MA) properties. Specifically, at a thickness of 1.04 mm, the composite exhibits the effective absorption bandwidth (3.92 GHz; 14.08–18.00 GHz), surpassing that of Ti3C2Tx. At a thickness of 0.98 mm, it exhibits a maximum reflection loss of −40.28 dB at 17.25 GHz, which substantially exceeds that of Ti3C2Tx. Furthermore, it shows a maximum Radar Cross Section reduction of 21.32 dB cm2. A cotton fabric was coated with N–Ti3C2Tx@Fe3O4, and it was found to exhibit enhanced heat conduction and dissipation, at rates 3.83 and 4.64 times greater than those of uncoated cotton, respectively. These results highlight the considerable potential of N–Ti3C2Tx@Fe3O4 nanocomposites for use in far-field applications. It is envisaged that the exceptional MA and thermal management properties of N–Ti3C2Tx@Fe3O4 nanocomposites will provide a novel avenue for crafting lightweight and thin EMW absorbing materials.

Construction of 1D heterogeneous PPy@FeCo@PPy nanotubes with broadband and strong electromagnetic wave absorption

Developing nanomaterials with efficient electromagnetic wave absorption to eliminate increasingly serious electromagnetic pollution is of great significance. The peculiar electromagnetic characteristics of one-dimensional dielectric-magnetic heterostructures bring a promising strategy for designing high-efficiency absorber. Herein, a hierarchical PPy@FeCo@PPy nanotube was fabricated through a process of oxidative polymerization and electroless plating. In the product, the FeCo nanoparticles are encapsulate in the middle of the polypyrrole (PPy) dual conductive layers, which facilitates the deep construction of heterointerfaces and simultaneously prevents magnetic agglomeration. Furthermore, the hollow structure and suitable dielectric-magnetic component optimize impedance matching. Profiting from the reasonable structural design and the strong synergistic loss mechanism of dielectric-magnetic, the coaxial multi-shell PPy@FeCo@PPy nanotube exhibits prominent electromagnetic wave absorption performance, with a minimum reflection loss of −50.5 dB and the effective absorption bandwidth of 5.7 GHz at 2.0 mm. This work offers a gentle strategy for preparing ideal microwave absorbers by constructing dielectric-magnetic heterogeneous interfaces.

Vat photopolymerization 3D printing SiBCN ceramic metamaterials with strong electromagnetic wave absorption

Starting from the simulation prediction, SiBCN polymer-derived-ceramic metamaterials, integrating both structure and function in a single component, were obtained using vat photopolymerization technology starting from a preceramic polymer. The low-density gyroid triply periodic minimal surface (TPMS) structures used in this study increases the multiple reflection loss of electromagnetic wave (EMW) in the macro-interpenetrating channel structure, generates surface characteristics (stair-stepping effect) structure interface polarization, and improves microwave absorption characteristics. The possible multiple reflection effects of a gyroid structure on electromagnetic waves are discussed by Computer Simulation Technology simulation. At the same time, the precipitated phases in polymer derived ceramics (PDCs) were adjusted by controlling the pyrolysis temperature. The results show that the crystal phases (such as β-SiC and C) precipitated in the gyroid structure sample pyrolyzed at 1200°C enrich the heterogeneous interface polarization in the material. In addition, C forms a (semi-)conductive network, which increases the conductivity loss. The effective absorption bandwidth (EAB, RL<-10 dB) of the samples pyrolyzed at 1200°C was 3.09 GHz (thickness of 2.21 mm) and the minimum reflection loss (RLmin) was −70.6 dB (thickness of 2.31 mm), indicating that the samples have favorable EMW absorption properties and great potential for applications, providing a foundation for the preparation of high-performance lightweight structural ceramics.

Rational design of SiBCN ceramics with excellent attenuation to strong electromagnetic-wave-absorbing properties at low frequency

To achieve strong electromagnetic wave absorbing properties, it is important to have good impedance matching, moderate electrical conductivity, and high polarization loss, particularly at low frequency. However, meeting these requirements for polymer-derived ceramics remains challenging. This paper proposes a simple approach to addressing this challenge by adjusting the crystallinity and defects of SiBCN ceramics. The addition of Sm as a catalyst and tailored heating temperatures were used to create SiBCN ceramics with adjustable crystallinities and defective nanograins. The controlled crystallinity provided good impedance matching, while the tailored defective nanograins offered high polarization loss. The combination of these factors results in high-performance electromagnetic wave absorption, with the SiBCN ceramics achieving a minimum reflection loss of −59.13 dB at 3.6 GHz and an effective attenuation bandwidth of 6.87 GHz with a thickness of 2.22 mm. This study provides an effective strategy for the design and fabrication of strong EMW absorbing materials.

Simultaneous rotary and linear displacement sensor based on soft pneumatic sensing chambers

Specific industrial or research applications necessitate specialized displacement measurement conditions, thereby driving researchers to innovate sensors based on novel operating principles. One such challenging condition is the prevalence of strong electromagnetic waves, which precludes using any sensor with a metallic structure or one that operates on electrical measurement principles. Additionally, space constraints in applications requiring multidimensional displacement measurements mandate the development of sensors capable of measuring displacements simultaneously in multiple directions. This paper introduces a novel soft sensor designed to simultaneously measure linear and rotational displacements using Soft Pneumatic Sensing Chambers (SPSCs). This sensor is unique in its ability to measure both linear and rotational movements and, due to its Electro-Magnetic Compatibility (EMC) and compact size, is suitable for environments with significant electromagnetic interference and spatial constraints. Furthermore, its flexibility makes it appropriate for body-interacting applications. The Abaqus software was employed to optimize the operating parameters. Subsequently, a laboratory setup was assembled, and the sensor's performance was assessed using two calibration methods: mathematical modeling and machine learning. According to the machine learning method, the accuracy in the linear and rotational directions was 0.49 mm and 5.4°, while the Root Mean Square Error (RMSE) was 0.05mm and 0.48°, respectively.

IIIA-IIB multicomponent perovskite rare earth ferrites with promising electromagnetic wave absorption properties

Perovskite-type rare-earth ferrites (REFeO3) are promising materials for absorbing electromagnetic (EM) wave pollution. However, insufficient dielectric loss and poor impedance matching are key factors that limit the broader implementation of REFeO3. Herein, a series of multicomponent perovskite-type ferrites with strong EM wave absorption capabilities was prepared. Through the synergistic effect of chemical constitution regulation and entropy regulation, optimization of the dielectric loss and impedance matching is achieved by strengthening the structural defect mechanism, thus further adjusting the EM wave absorption performance. Compared with (LaGdSmNdBa)FeO3 (HE-1) and (LaGdPrSmNdBa)FeO3 (HE-2), (LaGdBa)FeO3 (ME-1) and (LaGdSmBa)FeO3 (ME-2) exhibit favorable performance, with optimal minimum reflection loss (RLmin) of −56.35 dB (at 11.12 GHz) and −63.25 dB (at 7.22 GHz) and effective absorption bandwidth (EAB) of 4.46 and 4.72 GHz, respectively. This multicomponent design provides a new strategy for the development of EM wave absorption materials.

Theoretical Study of the Nernst Effect in Compositional Superlattices in the Presence of Strong Electromagnetic Wave

The Nernst effect has been theoretically studied in compositional superlattice in the presence of a strong electromagnetic wave. Using the quantum kinetic equation for electrons with two cases electrons-acoustic phonons scattering and electrons-optical phonons scattering, we obtained the analytic expression of the Nernst coefficient and kinetic tensors as a function of the magnetic field, temperature, frequency, and amplitude of the electromagnetic wave and parameters of the compositional superlattice. The dependence of the Nernst coefficient on the magnetic field and temperature is achieved by numerical calculations for AlGa/AlGaAs material. The result indicates that in the case of electron-acoustic phonon scattering, the Shubnikov-de Hass oscillation appears. Whereas, in the case of electrons-optical phonons scattering, the peak of magneto-photon-phonon resonance appears. In both cases, when temperature increases, the Nernst coefficient decreases rapidly, and for electrons-optical phonons scattering, the resonance peak has a movement.&#x0D;

Atomic Valence Reversal-Induced Polarization Resonance Spurs Highly Efficient Electromagnetic Wave Absorption in α-Fe2O3@Carbon Microtubes.

Variegation and complexity of polarization relaxation loss in many heterostructured materials provide available mechanisms to seek a strong electromagnetic wave (EMW) absorption performance. Here we construct a unique heterostructured compound that bonds α-Fe2O3 nanosheets of the (110) plane on carbon microtubes (CMTs). Through effective alignment between the Fermi energy level of CMTs and the conduction band position of α-Fe2O3 nanosheets at the interface, we attain substantial polarization relaxation loss via novel atomic valence reversal between Fe(III) ↔ Fe(III-) induced with periodic electron injection from conductive CMTs under EMW irradiation to give α-Fe2O3 nanosheets. Such heterostructured materials possess currently reported minimum reflection loss of -84.01 dB centered at 10.99 GHz at a thickness of 3.19 mm and an effective absorption bandwidth (reflection loss ≤ -10 dB) of 7.17 GHz (10.83-18 GHz) at 2.65 mm. This work provides an effective strategy for designing strong EMW absorbers by combining highly efficient electron injection and atomic valence reversal.

Surface modification by CO2 plasma boosting core shells structural Fe/Fe3C/FeN @ graphite carbon nanoparticles toward high performance microwave absorber

The surface modification of three-dimensional (3D) materials is an efficient method for adjusting their interfacial defect concentration, electronic conductivity and content of functional groups with extensive applications in catalysis, electrode materials and bioengineering. In this work, a multiphase iron nanocrystals consisting of Fe3C, Fe and FeN nanoparticles encapsulated in hierarchical structure of graphite carbon (denoted as Fe/Fe3C/FeN@GC) is synthesized for the first time by a novel high temperature plasma method. Meanwhile, more defects and functional groups are introduced by surface modification of graphite carbon layer of Fe/Fe3C/FeN@GC with controllable CO2 (low temperature) plasma. Benefiting from the advantages of multiple heterogenous interface and the abundant interfacial polarization relaxation that represent strong electromagnetic (EM) wave dissipation as well as an applicable impedance matching, the optimized Fe/Fe3C/FeN@GC demonstrate superior microwave absorption (MA) properties. The minimum reflection loss (RL) achieves −54.4 dB (more than 99.9% MA) at 17.6 GHz with a thin thickness of 1.8 mm, and the maximum effective absorption bandwidth (EAB, RL < −10 dB) is up to 6.2 GHz (11.8–18.0 GHz) at 2.0 mm. The above results reveal that the optimized Fe/Fe3C/FeN@GC composites with strong absorption, broad EAB, light mass (only filling content of 30 wt%) and ultrathin thickness are prospective candidate for high performance EM wave absorbers.

The Influence of an External Magnetic Field on Multi-photon Non-linear Absorption Coefficient of a Strong Electromagnetic Wave in Two-dimensional Graphene

Based on the quantum kinetic equation for electrons, we theoretically study the Quantum Multi-photon Nonlinear Absorption of a Strong Electromagnetic Wave (EMW) in two-dimensional Graphene with electron-optical phonon scattering mechanism. The general multi-photon absorption coefficient is presented as a function of the temperature, the external magnetic field, the photon energy, and the amplitude of external EMW. The results show that in the presence of the magnetic field, absorption spectral lines appear consistent with the magneto-phonon resonance conditions. In which, the effect of multi-photon absorption is stronger than that of mono-photon absorption. Besides, the quantum multi-photon nonlinear absorption phenomenon has been studied from low temperature to high temperature. This transcends the limits of the classical Boltzmann kinetic equation which is studied in the high-temperature domain. The computational results show that the dependence of Multi-photon Nonlinear Absorption Coefficient (MNAC) on the above quantities is consistent with the previous theoretical investigation. Another novel feature of this work is that the general analytic expression for MNAC shows the Half Width at Half Maximum (HWHM) dependence on the magnetic field which is in good agreement with the previous experimental observations. Thus, our estimation might give a critical prediction for future experimental observations in graphene.&#x0D; Keywords: Multi-photon non-linear absorption coefficient, 2D graphene, quantum kinetic equation, strong electromagnetic wave, electron-phonon scattering, magneto-phonon resonance.

MOF Derivatives with Gradient Structure Anchored on Carbon Foam for High-Performance Electromagnetic Wave Absorption.

The impedance matching and high loss capabilities of composites with homogeneous distribution are limited owing to high addition and lack of structural design. Developing composites with heterogeneous distribution can achieve strong and wide electromagnetic (EM) wave absorption. However, challenges such as complex design and unclear absorption mechanisms still exist. Herein, a novel composite with a heterogeneous distribution gradient is successfully constructed via MOF derivatives Co@ nitrogen-doped carbon (Co@NC) anchored on carbon foam (CF) matrix (MDCF). Notably, the concentration of MOF can easily control the gradient structure. In particular, the morphologies of MOF derivatives on the surface of CF undergo a transition from the collapse of the inner layer to the integrity of the outer layer, accompanied by a continuous reduction in the size of Co nanoparticles. Correspondingly, enhanced interface polarization from the core-shell of Co@NC and good impedance matching of MDCF can be obtained. The optimized MDCF exhibits the minimum reflection loss of -68.18dB at 2.01mm and effective absorption bandwidth covering the entire X-band. Moreover, MDCF exhibits lightweight characteristics, excellent compressive strength, and low radar cross-section reduction. This work highlights the immense potential of composites with heterogeneous distribution for achieving high-performance EM wave absorption.

Thermally assisted layer-layer crosslinking towards programmable evolution of pore structures for tunable electromagnetic response capability.

The research and development of aerogel-based microwave absorbing materials with strong electromagnetic (EM) wave response is an emerging research topic in the EM wave absorption field. In order to implement light microwave absorbers with a broad bandwidth, freeze drying assisted with in situ thermally structure-directing techniques was applied to fabricate composite aerogels with orientation design. Thanks to the integration of pore structure regulation and conductive network construction, the as-prepared aerogel absorbers exhibit a tunable EM response covering a broad frequency range. In detail, the maximum reflection loss (RL) value of the CR-3 aerogel reaches -50.8 dB at 2.2 mm and its maximum effective absorption bandwidth reaches 5.4 GHz at 2.0 mm, which is in accordance with the numerical simulation results of the radar cross section (RCS), where the optimum RCS reduction of 21.4 dB m2 appears for the CR-3 aerogel when the detection theta was set as 0°. In all, this work paves the way for the exploration of high-efficiency aerogel absorbers by balancing the evolution of the pore structure and conductive connection at the same time.