Electromagnetic Microwave Research Articles

Glucose derived carbon encapsulated boron nitride core-shell composites for efficient electromagnetic microwave absorption

Hexagonal boron nitride (h-BN) has the advantages of outstanding insulation, high thermal conductivity and excellent chemical stability, which promote the wide application of h-BN in thermal interface electronic packaging and other related fields. However, due to the poor dielectric loss ability of h-BN, which leads to its weak absorption capacity of electromagnetic waves (EMW), so it limits its practical application in related advantageous fields. In this paper, glucose-derived carbon-encapsulated BN core-shell composites (C@BN) were prepared by a simple hydrothermal reaction followed by high-temperature pyrolysis. The dielectric loss capacity of the C@BN was investigated by manipulating the concentration of glucose solution and pyrolysis temperature. Specifically, by adjusting the glucose derived carbon defect to induce polarization loss and impedance matching performance, so that more EMW entering the interior of the composite is absorbed and dissipated. The results show that C@BN obtained at 800 °C shows the best EMW absorption performance when the concentration of glucose solution is 3.6 wt%. The minimum reflection loss value (RLmin) is −43.5 dB and the maximum width effective absorption bandwidth (EABmax) of 6.72 GHz. Therefore, this study provides a reliable reference for the preparation of h-BN based EMW absorbing materials.

Preparation of high-performance bitumen carbon-based microwave absorbing materials from different coal bitumens toward efficient treatment of industrial waste bitumen

The increasing development of communication technology and electromagnetic pollution have accelerated the research and optimization of electromagnetic microwave absorbing materials. There are few studies and reports on the creation electromagnetic microwave absorbing materials from industrial waste, despite the abundance and promise of research preparing of microwave absorbing materials utilizing sustainable resources from biomass. Herein, we prepared carbon-based microwave absorbing materials GCB-800, HTCB-800, and CDLB-800 using three different industrial solid waste bitumens, namely, coal direct liquefaction bitumen, high-temperature coal bitumen, and globular coal bitumen, as raw materials by using the thermal activation method. Due to the excellent porous carbon skeleton structure and the Fe2O3 contained in its internal ash after the heat treatment, which enhances the internal dielectric properties, the CDLB-800 was found to perform very well at the filler amount of 10 wt% obtained minimum reflection loss (RLmin) is −52.41 dB at 10 wt% filler and matched thickness d = 2.1 mm, and the effective absorption bandwidth (EAB) is 4.88GHz, with 87.14% absorption for X-band in the 2-18GHz. This work not only promotes the development of the comprehensive utilization of solid waste in this field, effectively reduces the burden of solid waste on the environment, but also points out the direction for the development of microwave absorbing materials in the future.

Enhanced electromagnetic wave absorption of magnetite-spinach derived carbon composite

The high density, high cost, and environmental pollution hinder the application of iron-based electromagnetic wave-absorbing materials. Although bio-carbon is a green and lightweight dielectric wave-absorbing material, the wave-absorbing performance of bio-carbon is still limited. This work successfully combined magnetite Fe3O4 with porous carbon derived from spinach stem using hydrothermal and calcination methods. This process optimizes the matching of the dielectric constant and magnetoconductivity of the as prepared composite material, resulting in a significant improvement in electromagnetic microwave absorption capacity. XRD, SEM, TEM, XPS, VSM and EMW absorption network analyzer are used to detect and characterize the samples. The composite material shows a excellent minimum reflection loss value of −48.81 dB and an efficacious absorption bandwidth of 4.73 GHz at the optimal raw material ratio. The tests also show the porous structure of the sample with the coercivity and saturation magnetization of 29.36 Oe and 10.75 emu/g, respectively. The test results indicate that the excellent electromagnetic wave absorption is due to the synergistic effect of multiple reflection, Debye relaxation, and interfacial polarization. This Fe3O4-bio-carbon composite is cheap and simple to prepare, and it also has excellent wave absorption performance. Therefore, it shows great application potential in civilian and military electromagnetic wave absorption fields.

Synthesis of Ti3C2Tx-MXene/PAN-derived double-loss Co/CeO2/TiO2/CNFs nanocomposites for enhanced microwave absorption performance

With the advancement of wireless communication and electronic equipment, microwave absorption materials (MAMs) have more and more broad applications in related fields. Ti3C2Tx-MXene with unique two-dimensional structure and excellent dielectric properties is often used as a precursor of nano-TiO2, which is a potential MAMs. Carbon nanofibers, as a one-dimensional material, have great electrical conductivity and can form interconnected three-dimensional conductive networks. In this study, Ti3C2Tx-MXene was prepared by in-situ HF etching method, and further combined with the benefits of Co, Ce metals, and carbon nanofibers. Co/CeO2/TiO2/CNFs were prepared via a facile technique for electromagnetic microwave (EM) absorption, exhibiting excellent EM absorption performance due to the synergistic effects of dielectric and magnetic properties. The minimum reflection loss (RLmin) and effective absorption bandwidth (EAB) reache −63.35 dB (11.2 GHz) and 3.6 GHz (9.5–13.1 GHz), with a thickness of only 2.35 mm and a filling rate of 30 wt%, while the maximum EAB reaches 5.4 GHz (12.4–17.8 GHz) with a thickness of 1.82 mm, covering nearly the entire Ku band. By offering a novel strategy to the creation of brand-new, high-performance MAMs based on 1D carbon nanofibers with dielectric/magnetic synergy, this work is believed to support the development of upcoming MAMs.

Facile synthesis of vaterite CaCO3 microspheres from carbon capture and solid waste utilization towards microwave absorption and dye wastewater adsorption

Mineralization of CO2 to minerals like calcium carbonate (CaCO3) has been considered as an effective approach to combat global warming. In this paper, Ca2+ ions were firstly extracted from waste carbide slag, and then facilely transformed to vaterite CaCO3 via disperse bubbling carbonization method assisted with an air stone. By optimizing the reaction conditions, highly mono-dispersed vaterite CaCO3 microspheres (VCMs) were obtained. These microspheres consisted of aggregated CaCO3 nanocrystals, bearing a mesoporous structure. As a proof-of-concept, these mesoporous microspheres were utilized for dye adsorption and electromagnetic (EM) microwave absorption. For the former, the VCMs were used to adsorb Congo red, yielding a fast adsorption time of 9 min and a high adsorption capacity of 138.77 mg/g. For the latter, EM microwave dielectric parameters were measured, and dye-adsorbed VCMs exhibited better microwave-absorption performance with a minimum reflection loss of −43.2 dB, about 3 times of pristine vaterite. To the best of our knowledge, this is the first report of solid-waste-derived VCMs as microwave absorbent and dye adsorbent. Considering the low-cost, eco-friendly and facile preparation and effective utilization of VCMs, our work provides a promising strategy for large-scale carbon capture, solid waste utilization, and treatment of microwave and wastewater pollution.

Superior microwave absorption properties of anisotropic Y2Fe16‒xCoxSi/paraffin composites by orientation tuning

Y2Fe16-xCoxSi/paraffin composites were prepared by three different orientation methods. The effect of these orientation methods and the magnetocrystalline anisotropy of Y2Fe16‒xCoxSi alloys on the electromagnetic parameters and the microwave absorption properties were investigated. The results demonstrated that orientation tuning improved the electromagnetic parameters and microwave absorption properties. Anisotropy in dielectric properties and magnetic properties of Y2Fe16-xCoxSi/paraffin composites were achieved by tuning the orientation of Y2Fe16-xCoxSi powders. The planar and conical anisotropic materials had superior microwave absorption properties than uniaxial anisotropic materials for the same orientation method. The Y2Fe16‒xCoxSi/paraffin composite had an effective absorption bandwidth of 8.4 GHz (9.6–18 GHz) and a reflection loss of ‒59.6 dB which can almost cover the X–Ku bands and exceed the performance of many reported absorbing materials, showing its great prospects for microwave absorption in the X–Ku bands.

Reflection modulation generated by scale-free network resonator periodic structure

The pattern of resonator in a periodical array is decisive for its response under impinging electromagnetic wave. A scale-free network resonator is proposed by connecting sub-units in the form of scale free network. Scale-free network resonator array’s reflectivity near resonant frequency could be modulated at arbitrary value between zero and unity, which is different from known resonator array or frequency selective surface. Reflection amplitude modulation could generate rich behaviors, as effective medium property in wide band could be maintained near zero constant, which means zero phase shift and is favorable in radar radome structure. S-parameter analysis indicates amplitude modulation is owing to polarization conversion generated by network links. Scale-free network resonator array has application potentials in future radar radomes, electromagnetic wave lens and microwave antenna panels.

A combined theoretical, computational, and experimental investigation to evaluate performance of suitable thermocouple for microwave processing

Accurate temperature measurement during any microwave processing of material is a contentious issue. While thermocouples are routinely utilized in conventional heat furnaces, their presence in microwave cavities may cause complications such as localized distortion of electromagnetic field, heat dissipation, thermal instabilities, microwave breakdown, and significant inaccuracies in temperature measurement. Therefore, in the present investigation thermocouple effects are discussed by providing the results of temperature estimation by various thermocouples for microwave cladding systems. The present study theoretically and experimentally explored the impact of multiple thermocouples on temperature measurements during microwave heating. COMSOL simulation models were developed to explore microwave and thermocouple interaction during microwave heating. Simulation models were used to assess the effects of the microwave power intensity, thermocouple orientation, and geometry on temperature measurement. The investigation outcomes can be utilized as a guide for selecting appropriate thermocouples in the applications of microwave cladding and other microwave-based manufacturing processes.

Two birds with one stone: High electromagnetic interference shielding effectiveness and high thermal conductivity of ternary polyvinyl alcohol/graphene/ carbonyl iron nanocomposite films

Gaining brilliant flexible, easily-processable, bendable, low-density and high electrical conductivity (σ) materials with an excellent electromagnetic-interference (EMI) shielding performance is urgently needed in the fields of aerospace, aircraft, military, wearable and portable electronic industries. Therefore, the growing desire towards miniaturizing and developing high-frequency electronics is increasing incredibly today and grabbing much attention, however, they cause extreme heat accumulation and EM radiations that affect their performances as well as their hazardous effects on human health. So, polymer nanocomposites with high thermal conductivity (k) and EMI shielding effectiveness (SE) synchronously are urgently required to consume the generated heat and blocks the EM waves. Herein, poly(vinyl alcohol)/graphene nanosheets/carbonyl iron (PVA/GRx/CIR0.1-x) nanocomposite films are introduced as a new alternative candidate for EMI shielding applications with high in-plane k//, high mechanical functions, and EMI SET performance. The synergistic effect of GR and CIR on EMI shielding functions, thermal stability, mechanical properties, electrical features, and surface morphology has been explored. The increase in GR(x) amounts provides continuous GR layers and dense networks for conducting electrons and heats, provides the films with an admirable k// and total SE (SET) synchronously. Particularly, the PVA/GR0.08/CIR0.02 films have shown an σ of 1.72 Sm−1, a large SET of 32.94 dB and a specific SE (SSE/t) of 4365 dBcm2g−1 due to the mutual role (effect) of both high electrical conductive graphene and high magnetic carbonyl iron in cancelling the magnetic and electric fields of the incident EM waves. Moreover, the layered structure of GR endows films with a high k// of 3.62±0.11 W/(m·K), which is 14-fold larger than that of green PVA. The high compatibility and fine dispersion of GR/CIR fillers endow the films with a high Young modulus of 2.16 GPa, which is 7-fold larger than that of green PVA. This work suggests a novel and feasible scheme for producing high EMI shielding and high thermal conductive polymeric films, which will have huge prospects in advanced technology such as electromagnetic (microwave) interference shielding, wearable, biological, smart fabrics, military technologies and electronic equipments.

A green mediated synthesis of glass fiber‐nickel ferrite‐ polyaniline ternary composite: An excellent thermal stability and outstanding electromagnetic interference shielding performance

AbstractThe present study reports the preparation of a ternary composite with enhanced shielding performance toward electromagnetic waves using in situ polymerization of aniline on fiber‐ferrite binary composite. The polymerization is carried out in a green medium lime juice, which acts as an efficient dopant. The composite is amalgamated with varying weight percentages of ferrite (ranging from 25% to 100%) while maintaining a constant weight percentage of fiber. The presence of the fiber in the binary and ternary composite could enhance the thermal stability of the material, highlighting its applicability in a wide range of temperatures. The DC conductivity, AC conductivity, and dielectric properties are investigated, revealing significant performance enhancements. The ternary composite demonstrates excellent conductivity in the range of 10−210−1 S/cm, attributed to the polaron/bi‐polaron interaction paradigm. Furthermore, the electromagnetic interference shielding, microwave absorption, and reflection capabilities of the composites are assessed within the frequency range of 8–12 GHz. The optimized composite, featuring aniline (0.4 M) and glass fiber with ferrite in a 1:1 ratio, exhibits an outstanding shielding value of 32 dB. These results point toward the potential of this ternary composite material as an effective shield against electromagnetic pollution.

Microwave absorption performance for Cu, Co, and Ti co-doped SrFe12O19 as a function of incident angle

Microwave-absorbing materials (MAMs) are essential for mitigating the unwanted effects of electromagnetic interference and microwave pollution. MAMs are also used in 5G technology, energy harvesting, information security, and military technology (such as reduced radar cross-section). In this work, SrFe12–2xCux/2Cox/2TixO19 samples, prepared by using a ball mill and heat treatment method, showed their superior microwave dissipation features in both effective absorption bandwidth (EAB) and reflection loss (RL) values for the microwave incident angle of 0°, where EAB and RL values reached 15.90 GHz and −42.86 dB, respectively. The optimum RL values would change with the variation of the incident microwave angle. RL values at a specific oblique angle could exhibit better RL values for both transverse electric (TE) and transverse magnetic (TM) polarization modes, except for the x = 0.15 (SrM15) sample for TE mode. In detail, the x = 0 (SrM0) sample achieved the lowest RL value of −71.28 dB for the incident angle of 20° in the TE polarization mode, which was much better than that of the normal incident. The RL of the SrM15 sample in TM mode was significantly enhanced and reached a value of −66.48 dB for an incident angle of 10°. The increase in the RL values resulted from the superior values of complex permittivity and permeability and their matching. In addition, the improvement in RL values could be attributed to the increase in incident and refraction angles as well as the longer pathway of the microwave inside the samples. These discoveries also illustrate that SrFe12–2xCux/2Cox/2TixO19 samples hold promise for various everyday applications, even when exposed to oblique angle variation.

Tailoring permittivity and permeability of M-type hexagonal ferrite and 2D Ti3C2Tx MXene composites for broadband microwave stealth performance

In this study, owing to the significant advantages of heterogeneous interface engineering for customizing the electromagnetic parameters and microwave absorption properties, high magnetic lossy cobalt/zinc-doped hexagonal ferrite flakes were successfully anchored on two dimensional Ti3C2Tx with varying mass ratios. Inorganic Ti3C2Tx MXene was synthesized through the hydrofluoric acid etching process, and doped hexagonal ferrite was prepared by a solid-state sintering route leading to electrostatic bonding with Ti3C2Tx particles. Scanning electron microscopy revealed that the MXene surface strongly adhered to the ferrite particles. By adjusting the ratio of ferrite to Ti3C2Tx, it is feasible to optimize electromagnetic parameters, as required. Specifically, doped ferrite@4% Ti3C2Tx MXene composite exhibited remarkable absorption performance; the maximum reflection loss (RL) was −49 dB at 15.2 GHz with a thickness of 1.9 mm. The effective bandwidth corresponding to the RL values below −10 dB is 8.3 GHz (from 9.7 GHz to 18 GHz) at a single thickness of 2 mm, and below −15 dB is 6.4 GHz (from 10.7 GHz to 17 GHz), outlining the prospect for application as an electromagnetic wave absorber. Radar cross-section (RCS) simulation was performed with microwave incident angles ranging from 0 to 360°. The results demonstrate a reduction in RCS of up to −47.8 dBsm at a 60° incident angle. This study develops a new approach for constructing multi-component heterostructure composites with tailored electromagnetic parameters as a superior and modulated radar stealth material.

3D-printed conical structure absorber based on NFG/Fe3Si/SiCnw ternary composites for multifunctional integrated electromagnetic microwave absorption

The wave absorbers with dual functions of structural load-bearing and radar absorption have become the solution strategy to cope with the increasingly complex electromagnetic environment. In this paper, a conical structure absorber based on natural flake graphite (NFG)/Fe3Si/SiCnw ternary composites was successfully prepared by selective laser sintering (SLS) 3D printing technique starting from multi-scale design. From the material level, the in-situ grown one-dimensional SiC nanowires effectively improve the dielectric properties of the material, which increases the magnetic/dielectric loss synergy together with the magnetic material Fe3Si. The minimum reflection loss is −54.21 dB and the effective absorption bandwidth (EAB) is 4.6 GHz when the thickness is 1.5 mm. The unit structure of the conical structure absorber was structurally designed and experimentally verified at the structural level, and broadband electromagnetic absorption at 14.45 GHz was achieved and the compressive yield stress was 5.21 MPa. In addition, the EAB of both transverse electric-polarization (TE) and transverse magnetic-polarization (TM) under the variation of incidence angle from 0 to 50° exceeded 12 GHz, indicating that the conical structure absorber has excellent wide-angle absorption properties. The broadband microwave absorption performance of conical structure absorbers is attributed to the synergistic enhancement effect of improved impedance matching on the macroscopic scale and multiple electromagnetic loss mechanisms on the microscopic scale. The conical structure absorber prepared by SLS achieves material-structure-function integration of electromagnetic microwave absorption, and the multifunctional integrated design contributes to the practical application of stealth technology in the field of industrialized electromagnetic microwave absorption.

Analysis and research on the teaching reform of electromagnetic wave and microwave technology under the background of new business form

This paper studies the higher education in the national economic form change, college students learning state new form, education and industry, education information under the background, for profound theory, experimental equipment expensive, experimental conditions, in the student theory of weak, try to need the education teaching reform direction and reform measures. Among them, the education and teaching reform of microwave technology curriculum was piloted as an example. For the weak theoretical foundation of electromagnetic field and insufficient mathematical foundation, the course adopts the strategy of light theory requirement, heavy phenomenon cognition, and guiding the application of knowledge to practice. Through virtual simulation, the invisible electromagnetic field and electromagnetic wave make it easier for students to understand the knowledge context to form the knowledge system; Through online and offline mixed teaching, stress response teaching, promote students 'participation in classroom teaching, improve students' independent thinking ability and judgment and analysis ability, attract students' attention in classroom learning, and interest in the corresponding knowledge content. And then promote the students' self-study ability, research ability and design ability.

Electromagnetic Characteristics and Microwave Absorbing Properties of a Novel Stainless Steel Powder

In order to solve the problem of insufficient oxidation resistance and corrosion resistance of magnetic metal absorbent represented by carbonyl iron powder, a wave absorbing composite material which consists of different filling mass proportions of the atomized electrolytic stainless steel powder and paraffin wax is investigated. The electromagnetic (EM) characteristics and absorbing performance of the proposed composite material were tested with Agilent N5234A vector network analyzer in a frequency range of 2–18GHz. The experimental results show that the real and imaginary parts of the dielectric permittivity of stainless steel powder/paraffin composites will increase with the filling mass fraction in the test frequency band, while the real part of the permeability [Formula: see text] decreases with the increase of the mass fraction, and the imaginary part [Formula: see text] increases with the increase of the mass fraction. At a thickness of 3 mm, with the filling mass fraction increasing from 20 wt.% to 60 wt.%, the peak frequency of reflection loss (RL) moves to low frequency from 17.92 GHz to 16 GHz. Meanwhile, the minimum reflection loss (RL[Formula: see text]) also shows a downward trend, and the RL[Formula: see text] value with a filling mass fraction of 60 wt.% is −8.93[Formula: see text]dB. It can be seen that stainless steel powder shows good microwave absorbing performance, and it has excellent anti-oxidation, and anti-corrosion properties. Based on the excellent performance of stainless steel powder, its absorption performance is expected to be further improved through multi-layer optimization design, so as to meet the needs of electromagnetic protection in harsh environments.

Design and Development of Metamaterial Absorber for IoT Applications

Microwave absorbers are efficient design structures that enhance electromagnetic shielding and reduce electromagnetic wave interference. It dissipates an incident electromagnetic wave by converting it into other forms of energy, thereby preventing the electromagnetic wave's reflection and/or transmission. A novel electromagnetic metamaterial dual-band microwave metamaterial absorber for IoT application is proposed in this manuscript. The proposed absorber has an excellent absorption rate, above 98% and 99% at 2.4 and 5.1 GHz, respectively. The structure, designed over FR-4 material, provides negative permittivity and permeability. The Nicolson Ross Weir (NRW) method investigates metamaterial properties. An array of (3 × 3) unit cell absorbers is designed, developed, and tested; simulated and measured results are in good agreement.

Structural, thermal, magnetic and microwave-absorbing properties of spinel-structured high entropy oxide (MnFeCoNiX)3O4 (X = Zn, Cu, Cr)

Within the present work, a series of spinel-structured (MnFeCoNiX)3O4 (X = Zn, Cu, Cr) high entropy oxides (HEOs) were fabricated by co-precipitation method and the subsequent heat treatment. The phase composition, microstructure, thermal stability, magnetic property and electromagnetic (EM) wave loss ability were comprehensively studied. It is found that spinel-structural (MnFeCoNiX)3O4 HEOs are well-crystallized at above 800 °C with a space group Fd-3m. Morphological analysis reveals that grains of different HEOs contain nano-domains with particle sizes between 100 nm and 500 nm. In addition, Mn, Ni, Co, Fe, Zn, Cr and Cu elements are homogeneously distributed and the chemical states of Mn, Ni, Co and Fe are all +2 and + 3, while Cu only exists in +2 state. Thermal stability analysis shows that (MnFeCoNiCu)3O4 HEO is able to keep stable at 1000 °C. Moreover, the (MnFeCoNiCu)3O4 sample exhibits the best magnetic properties and EM microwave loss ability in comparison with (MnFeCoNiZn)3O4 and (MnFeCoNiCr)3O4. For (MnFeCoNiCu)3O4, the values of saturation magnetization (Ms) and coercivity (Hc) are 38.6 emu/g and 52.6 Oe, respectively. Meanwhile, (MnFeCoNiCu)3O4 displays a minimum reflection loss (RL) of −15.5 dB at 8.48 GHz with a thickness of 4.5 mm and a wide effective absorption bandwidth (EAB) of 8.84 GHz with the sample thickness of 5 mm. It is expected that the excellent high-temperature stability and good EM wave absorbing performance of high entropy (MnFeCoNiCu)3O4 could make it potentially useful in EM wave absorption under elevated temperatures.

Microwave heat-induced aggregation behavior of fish myofibrillar protein: New insights from nano- and micro-structural observation

The interaction between electromagnetic microwave field and biomacromolecule is not commonly understood, and the existence of the ‘microwave effects’ has been controversial. Herein, the aggregation behavior of fish myofibrillar proteins (MPs) induced by microwave heating (MW) and water bath heating (WB) was studied by using a range of electron microscopy techniques, including scanning electron microscope, cryo-SEM, atomic force microscopy, transmission electron microscope, and cryo-electron microscope. Through these methods, we hope to explore this issue from a multi-scale and dimensional perspective. In this communication, the unusual aggregation behavior of salt-soluble MPs under microwave irradiation was reported for the first time by controlling the same time–temperature heating curve with WB, yielding a dispersive and irregular structure with smaller particle size, subsequently generated a more stable, denser, and well-structured network. However, regional agglomeration behavior is more remarkable in WB treatment, which can lead to structural instability. These findings explained why microwaves can obtain protein gel with superior gel strength than WB from the structural perspective.

Efficient electromagnetic wave absorption of polypyrrole/low-reduction graphene oxide composites through dielectric properties modulation

Graphene oxide (GO) is widely used in electromagnetic microwave absorption (EMA) materials due to its abundant oxygen-containing functional groups and defects. Its conductivity, surface functional groups and defect density can be modified by controlling reduction degree to modulate its electromagnetic properties. However, the thermal reduction temperature needed is often too high, exceeding the Curie temperature of magnetic materials, which makes further compounding difficult. Polypyrrole (PPy), as a conductive polymer with high electrical conductivity, is widely used in EMA field and can help regulate the dielectric properties of materials. In this paper, a series of PPy/GO composites with different ratios and reduction degrees were prepared by in situ polymerization and thermal reduction, and their EMA properties were investigated. At a loading amount of 7.5 wt%, the maximum reflection loss of PPy/rGO composites can reach −66.64 dB, and the effective absorption bandwidth can reach 6.74 GHz with a reduction temperature of only 400 °C. Furthermore, the unreduced sample also has excellent absorption performance, which has a wide range of applications for future one-step compositing with magnetic materials in low reduction temperature.

Microwave Control of Reynoutria japonica Houtt., Including Ecotoxicological Aspects and the Resveratrol Content in Rhizomes.

Japanese knotweed (Reynoutria japonica Houtt.) is Poland's invasive weed, for which there is no efficient control method. The rhizomes of this species are rich in resveratrol. In this work, we evaluated (1) the effectiveness of electromagnetic microwaves (MV) in destroying Japanese knotweed using an original device, HOGWEED (MV of 2450 MHz), (2) the ecotoxic effect of the MV on the soil environment, and (3) the resveratrol content in knotweed rhizomes after MV treatment. The field studies were carried out in 2022 in southern Poland. Cut plants were MV-treated for times of 5.0-25.0 min. The MV efficiency was checked 10 and 56 days after treatment (DAT). After MV treatment, fresh soil samples were taken to analyze their ecotoxicity. As a result, at 56 DAT, knotweed was controlled if MV was used for at least 20.0 min. The MV did not affect the soil ecotoxicity. The MV-treated soils were classified as non-toxic or low-toxic. To analyze the resveratrol content, healthy knotweed rhizomes were dug out, treated with MV in the laboratory at 2.5-10.0 min, and analyzed for resveratrol content in HPLC-MS/MS. As a result, the resveratrol in the rhizomes significantly decreased in a time-dependent manner following MV exposure.