Electromagnetic Shielding Fields Research Articles

Depositing gradient thickness silver film on CNF/rGO/polyimide surface to form a sandwich structure for efficient electromagnetic interference shielding

Deployable satellites in space are exposed to high-frequency electromagnetic interference (EMI) for long periods of time, resulting in shortened lifetimes, so there is an urgent need for supportive electromagnetic shielding materials. To address this limitation, our team has developed innovative ultrathin carbon nanofiber/reduced graphene oxide/polyimide (CNF/rGO/PI) composites. It has excellent strength, shape memory properties, thermal stability and wide temperature range tolerance. Among them, polyimide with 4 % CNFs and 4 % rGO (CGPI44) has the best performance. Gradient-thick Ag films are deposited on both sides of the CGPI44 substrate by magnetron sputtering to form sandwich structure composites. With a sputtered Ag thickness of only about 5 μm and a total thickness of 0.146 mm, the material exhibited an extremely high electrical conductivity and excellent EMI shielding effectiveness (SE) of up to 112 dB in the 8.2–12.4 GHz band. Finite element analysis is performed to calculate the electric field strength and energy distribution. By providing a feasible scheme for highly effective shielding of high-frequency EMI, this approach will promote research on magnetron-sputtered polymer composites in the field of electromagnetic shielding.

Toughness and High‐Electromagnetic‐Shielding CPM Composite Film with Multilayer Sandwich Structure Based on Mxene

Electromagnetic shielding (EMI) films with excellent EMI and mechanical performances has been a hotspot in the EMI field. Herein, CNF/PDA@MXene (CPM) composite films exhibiting satisfactory mechanical and EMI properties are fabricated via vacuum filtration using PDA@MXene as the shielding layer and CNF/PDA as the mechanical layer. Results revealed that the optimal mass ratio of MXene to hydroxytyramine (DA) is 100:6 and that of CNF to DA is 70:30. The optimal arrangement is comprised by two layers of CNF/PDA and one layer of PDA@MXene. The breaking strength, breaking elongation, and toughness of the CPM composite film are 198.0 MPa, 2.9%, and 3.22 MJ m−3, which increased by 27.4, 3.5, and 106 times compared to those of a pure MXene film, respectively. Furthermore, the EMI efficiency of the CPM composite film reached 46.1 dB. Moreover, the EMI performance of the CPM composite film exhibited only slight changes under the conditions of ultrasonic shock, humid environment, and bending for 1000 times.

Broadband radar absorbing metamaterial based on Al @SiO2 conductive composite film.

Artificially designed metamaterial structures can manipulate electromagnetic waves, endowing them with exotic physical properties that are not found in natural materials, such as negative refractive index, superlens, and inverse Doppler effect. These characteristics are widely applied in various engineering and military applications. Due to increasingly complex application environments and innovation in radar detection technology, the combination of broadband absorption performance under thin thickness and efficient preparation methods at low cost is often the focus of research on new generation stealth materials. Here, we propose Al@SiO2 composite conductive film metamaterial (Al@SiO2 CCFM) to achieve wideband absorption of electromagnetic waves. This metamaterial structure combines two resonant units, resulting in three absorption bands in the absorption curve. The results show that the absorption rate of the metamaterial is above 90% in the frequency range of 10.6 GHz to 26.0 GHz. The resonance mechanism between multiple structures is a prerequisite for achieving wideband absorption. The materials Al and SiO2 used in Al@SiO2 CCFM are inexpensive and abundant, and the fabrication method is simple. Therefore, they hold great potential for large-scale applications in the multispectral stealth and electromagnetic shielding field.

Hollow Superstructure In Situ Assembled by Single-Layer Janus Nanospheres toward Electromagnetic Shielding Flame-Retardant Polyurea Composites.

A dodecahedral superstructure consisting of a single layer of Janus spheres containing ZIF-67 nanodots is prepared by in situ polymerization, with ZIF-67 and bio-based phytic acid (PA) as templates and dopants. It is used to improve the flame retardant, electromagnetic (EMI) shielding, and thermal conductivity properties of polyurea (PUA). By adding 5wt% polyaniline@cobalt phytate-2.0 (PANI@Co-PA-2.0), the peak of heat release rate and the peak of smoke production rate are reduced by 54.9 and 59.9%, respectively. The peak of CO and CO2 production also decreased by 46.2 and 53.1%, respectively. A decrease in the absorption intensity of aliphatic and aromatic volatiles is also observed. The fire safety of PUA is greatly improved. In addition, PUA/PANI@Co-PA-2.0 exhibits an EMI shielding capability of 22.4dB with the help of reduced graphene oxide, which confirms the possibility of PUA material application in the field of electromagnetic shielding. The 5wt% filler increases the tensile strength of the PUA matrix to 6.3MPa, and the composite material obtains good thermal conductivity. This work provides a viable method for the preparation of a flame-retardant, conductive, and electromagnetic refractory PUA substrate.

Ti3C2Tx MXene/delignified wood supported flame-retardant phase-change composites with superior solar-thermal conversion efficiency and highly electromagnetic interference shielding for efficient thermal management

The development of form-stable phase-change material (PCM) with solar-thermal harvest, electromagnetic interference (EMI) shielding, and flame-retardancy is crucial for efficient building energy management and conservation. Herein, novel Ti3C2Tx MXene/delignified wood supported form-stable phase-change composites (PMPCMs) with superior solar-thermal conversion efficiency, highly EMI shielding effects, and excellent flame-retardancy were fabricated by alkaline boiling delignification, ammonium dihydrogen phosphate (ADP) and MXene deposition, and melted n-octadecane impregnation. Benefiting from the powerful surface tension and capillary force of the wood-based support materials, PMPCMs can effectively encapsulate the melted n-alkane molecules and inhibit their leakage. The differential scanning calorimetry results showed that PMPCMs possessed superior n-octadecane encapsulation yield and high thermal energy storage density (166.9–191.6 J/g). Decorating delignified wood by MXene significantly improved the solar-thermal storage efficiency (up to 88.4 %) and EMI shielding performance of PMPCMs. The average EMI shielding effectiveness of PMPCM-10 was enhanced to 34.12 dB in X-band frequency range of 8.2–12.4 GHz. Moreover, with the introduction of the flame-retardant ADP, the peak heat release rate (pHRR) and total heat release (THR) of PMPCMs decreased noticeably, demonstrating the enhanced flame retardancy of delignified wood supported phase-change composites. In summary, PMPCMs exhibited superior application prospects in building energy management and electromagnetic shielding fields.

Flexible Basalt Fiber/Aramid Nanofiber/Carbon Nanotube Electromagnetic Shielding Paper with Outstanding Environmental Stability and Joule Heating Performance.

In the field of electromagnetic shielding, it has become an important trend to manufacture thinner and better-performing electromagnetic interference (EMI) shielding materials. However, EMI shielding materials that are recyclable and resistant to extreme environments are of great significance for sustainable development and expanding their application areas. In this study, a composite paper with a "rebar-concrete" layered structure through the vacuum-assisted filtration approach by utilizing basalt fibers (BF) and aramid nanofibers (ANFs) with excellent temperature resistance and multiwalled carbon nanotubes with high electrical conductivity was prepared. The composite paper not only delivers a high electrical conductivity of 15.9 S cm-1 and a high electromagnetic interference shielding efficiency (EMI SE) of 24.6 dB but also exhibits a high specific shielding efficiency (SSE/t) of 12,504 dB cm2 g-1 at a thickness of 48 μm. Thanks to the excellent thermal stability of basalt fibers and aramid nanofibers, the composite paper exhibits long-term stable EMI shielding performance and structural integrity in various extreme environments, including fire, high/low temperature (-196 to 300 °C), and acid-base corrosion. Furthermore, the BF/ANF/CNT composite paper also shows excellent Joule heating performance, rapid electrothermal response, and good temperature controllability. Based on these excellent properties, the BF/ANF/CNT composite paper shows tremendous potential for practical applications to meet the requirements of various extreme environments.

Heterogeneous asymmetric double-layer composite with ultra-low reflection for electromagnetic shielding

In this work, a heterogeneous asymmetric double-layer composite (HADC) consisting of an absorbing layer Fe3O4@reduced graphene oxide (rGO)/waterborne polyurethane (WPU) and a reflecting layer Ni-Co-P@FC (Ni-Co-P coated filter cotton (FC)/PANI@PDMS (polyaniline (PANI) mixed in polydimethylsiloxane (PDMS)) was designed and prepared using a simple chemical plating method and stirred foaming process. In which, the upper Fe3O4@rGO/WPU foam utilizes the combined effects of the porous internal structure and Fe3O4@rGO to achieve superior impedance matching and electromagnetic waves (EMW) absorption performance, while the Ni-Co-P dense conductive network formed by chemical plating process within the bottom layer ensures superior electromagnetic shielding effectiveness (EMI SE). The advantage of heterogeneous asymmetric structure combined with the reasonable distribution of electromagnetic two-component fillers and under the effects of multiple electromagnetic loss mechanisms, the composite structure perfectly overcomes the contradiction between efficient shielding and high absorption. Ultimately, the HADC exhibits a high EMI SE of 36.6 dB and absorption coefficients (A) value of 0.94, showing ultra-low reflection efficiency, which is better than most current shielding materials moreover, the preparation process is simple, with the characteristics of low cost and environmentally friendly. Therefore, this work provides a simple and feasible new idea for the preparation of lightweight, efficient and ultra-low reflection EMI shielding composite structures, which broadens the application of porous structures in the field of electromagnetic shielding.

In-situ magnetite deposited wood composites with extensive electromagnetic interference shielding performance

Wood is an insulator material, using its porous structure to endow it with efficient microwave absorption and broaden its application range is still a major challenge. Here, wood-based Fe3O4 composites with excellent microwave absorption properties and high mechanical strength were prepared by alkaline sulfite method, in-situ co-precipitation method and compression densification method. The results showed that the magnetic Fe3O4 was densely deposited in the wood cells, and the prepared wood-based microwave absorption composites had both high electrical conductivity, magnetic loss, excellent impedance matching performance and attenuation performance, as well as effective microwave absorption properties. In the frequency range of 2–18 GHz, the minimum reflection loss value was −25.32 dB. At the same time, it had high mechanical properties. Compared with the untreated wood, its modulus of elasticity (MOE) in bending increased by 98.77%, and modulus of rapture (MOR) in bending improved by 67.9%. The developed wood-based microwave absorption composite is expected to be used in electromagnetic shielding fields such as anti-radiation and anti-interference.

Improvement of absorbing stability of carbon nanofibers in sub-terahertz domain using the surface modification of zinc oxide

Carbon nanofibers (CNFs) is a typical electrical loss material with strong permittivity that has been widely used in the field of electromagnetic shielding, attenuation, and reception. However, studies have demonstrated that the unstable anisotropic EM behavior exhibited by CNFs in the terahertz domain hinders its application in the tremendously high frequency domain. In this study, ZnO is used to perform surface modification of CNFs based on the sputtering method, which effectively eliminate the anisotropic EM behavior of CNFs at different irradiation angles in the sub-terahertz band. ZnO coated the surface of fiber wall comprehensively in the form of nano-scale. The results show that after the surface modification, the composite sample exhibits a stable isotropic EM response in the sub-terahertz band of 500–750 GHz. Also, in the frequency range of 551–563 GHz (bandwidth: 12 GHz), ZnO not only acts as a stabilizer, but also enhances the absorption performance of the original CNFs by 6%, which is up to 92%. In the frequency range of 660–690 GHz (bandwidth: 30 GHz), the composite sample and the pure CNFs sample have similar wave absorption performance with about 75%, the maximum difference is less than 5%, and the minimum is about 2.6%.

Hierarchically Flexible Polyamide Composite Films for Thermal Management and Electromagnetic Shielding

With the integration and high power of electronic devices, as well as the rapid development of 5G and new energy, the application of materials with good flexibility, mechanical properties, and multifunctional properties is increasing. In this study, we prepared polyamide composite films with high thermal conductivity (TC) (33.27 W/(m·K)), excellent electromagnetic interference shielding effectiveness (EMI SE) (63.0 dB), and good mechanical properties (tensile strength 44.5 MPa, toughness 13.8 MJ/m3) by using hierarchical design and recombination strategy. The top layer of the composite film is a graphene/graphene oxide film (GNP/GO) as the TC and EMI shielding layer. The base layer of the composite film is a commercially available polyamide mesh to improve mechanical properties. The dense Ni layer was deposited on the polyamide fabric by the electroless nickel plating process, which improved the shielding performance against electromagnetic interference. The water-borne polyurethane (WPU) cladding is further coated on the nickel-plated polyamide fabric to protect the cladding and bond the top and base layers simultaneously. In addition, the practical application of the film in thermal management and electromagnetic shielding fields is also proved through the application experiments.

Controlled preparation of core-shell SiC/graphene powders by combustion synthesis

High-purity SiC/graphene powders with the core-shell structure were controllably prepared by combustion synthesis from Mg/SiC powders in 0.5 MPa CO 2 atmosphere. The maximum reaction temperatures were much higher than 1000℃, greatly promoting the vapor reaction between Mg and CO 2 . The thickness of synthesized graphene can be well regulated in the range of 1-10 layers by changing the Mg/SiC mass ratio in the raw materials. The graphene layers were complete and uniformly coated on the surface of SiC particles. The interface between SiC and graphene was clear and well bonded without any interface separation or amorphous layer. Further, core-shell SiC/graphene powders synthesized in this work have great potential for application in the field of electromagnetic shielding, photocatalysis, etc. • Core-shell SiC/graphene powders were controllably prepared by combustion synthesis. • The thickness of graphene can be well regulated in the range of 1-10 layers. • A clear interface with the good interface bonding exists between SiC and graphene.

Absorption-based electromagnetic interference shielding composites with sandwich structure by one-step electrodeposition method

The absorption-dominant electromagnetic interference (EMI) shielding materials with light weight, great flexibility, fast heat dissipation and excellent mechanical strength are highly demanded in civil and military applications. In this regard, the absorption-based CNT/Co composite film with sandwich structure (Co/Co-CNT/Co layer) was designed for highly EMI shielding performance and heat dissipation. The existence of Co layers on CNT/Co composite film has suitable impedance matching between film and free space, which can increase EM waves absorption and decrease EM waves reflection. Appropriately incorporating Co nanoparticles into the CNT film can facilitate the interfacial polarization, dipole polarization and dielectric loss derived from conduction loss, thus CNT/Co composite film shows high EMI shielding effectiveness (EMI SE: 49 dB), tensile strength (120 MPa), excellent electrical and thermal conductivity of 61.1 S/cm and 66.8 W/mK respectively. Furthermore, the ratio of absorption (SEA) and total EMI SE (SET) for pristine CNT film is 86.64% and for CNT/Co composite film is 93.31%, and the ratios of A/R for pristine CNT film (0.58) and CNT/Co composite film (1.20) manifest that the EMI shielding mechanism transforms from reflection to absorption. This work offers a novel method to develop the sandwich-structure composites with absorption-dominant EMI shielding performance in the application of advanced multifunctional electromagnetic shielding field.

On the electromagnetic shielding properties of carbon fiber materials

Introduction. Due to the good electrical and thermal properties of carbon, carbon-based materials represent a major trend is various applications, including electromagnetic compatibility. Among carbon-based materials, graphite-impregnated woven fabrics represent a new trend in the field of electromagnetic shielding, with the perspective of being used for protective clothing. The novelty of the proposed work consists in the exhaustive comparative analysis of various carbon-based sample shields by employing both simulation and experimental methods. The selected configurations included a simple graphite plate, a graphite powder strip network, and a graphite-impregnated fabric with 2´2 twill weave. Purpose. The main scope of the analysis is to prove the efficiency of the graphite-impregnated twill woven fabric in the field of electromagnetic shielding. Methods. Two main research methods were employed: simulation and experiment, both following the same protocol: the shield placed in the middle, with the excitation (transmitting antenna) on one side and the measurement / receiving antenna on the other. The experimental stage was thorough, being performed in two different laboratories and by applying the double transverse electromagnetic (TEM) cell method and the shielded box method. Results. A significant difference yielded from the comparison of the simulation and experimental results for the shielding effectiveness, probably due to the fact that the virtual model is an idealized version of the physical one, not taking into account its imperfections. The virtual analysis yielded the graphite plate shield as the most efficient, followed closely by the twill fabric. The graphite strip network had significantly poorer performance compared to the other two shields, probably due to the electrical contact imperfections between the graphite strips and the optical transparency of the shield. The main focus of the analysis was the twill woven graphite-impregnated fabric; therefore, its shielding effectiveness was determined through simulation and experiment. The experimental analysis was performed in two stages in two different electromagnetic compatibility laboratories, by employing the double TEM cell method and the shielded box method, respectively, both methods providing similar results and classifying the shielding performance as good. Practical value. The paper provides an accurate analysis of the graphite-impregnated 2´2 twill woven fabric in terms of electromagnetic shielding effectiveness, by employing both simulation and experimental methods, and comparing its performance to the one other graphite-based shields.

Hive‐Inspired Multifunctional Wood‐Nanotechnology‐Derived Membranes with a Double‐Layer Conductive Network Structure for Flexible Electronics

AbstractNext‐generation flexible electronics must achieve multifunctionality, environmental friendliness and antibacterial activity. Accordingly, organisms in nature are interconnected. Inspired by the honeycomb multilayer porous structure, a wood‐nanotechnology‐derived flexible membrane circuit is created to meet the abovementioned requirements. The flexible wood (FW) matrix is made of natural balsa wood that underwent a simple top‐down chemical treatment. The multiwalled carbon nanotube (MWCNT) acts as a “bridge” between the FW matrix with a porous array structure and the active material (silver nanoparticles (Ag NPs) and poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS). Due to the three‐dimensional porous microstructure and highly conductive surface inherited by the wood‐nanotechnology‐derived flexible membrane (FW/MWCNT/Ag/PEDOT:PSS), it shows a high area capacitance (266.7 mF cm−2 at 20 mV s−1) and a good long‐term cycling stability 84.3% capacitance retention after 5000 cycles at 5 mA cm−2 when used as a supercapacitor electrode. In addition, it shows an excellent specific electromagnetic shielding efficiency (up to 970 dB cm2 g−1), proving its application potential in the field of electromagnetic shielding. Because of the biocidal property of Ag NPs, the FW/MWCNT/Ag/PEDOT:PSS shows a remarkable antibacterial effect on Escherichia coli and Staphylococcus aureus. This strategy provides a new opportunity for researchers to design biomass‐based integrated electronic materials.

A study of preparation and properties of epoxy resin/carbon fiber/phenolic residual carbon composites with adjustable negative permittivity behavior

In recent years, there have been more and more researches on the dielectric properties of carbon-based composites, and its dielectric tunability is a hot research topic. In this paper, epoxy resin/carbon fiber/phenolic residual carbon (EP/CF/C) was prepared by high-temperature sintering, vacuum liquid phase impregnation and hot-press curing methods. The AC conduction behavior, dielectric properties and impedance properties of composites with different CF/C compression ratios (1, 1.5, 2) are studied. With the increase of CF/C compression ratio, the negative dielectric properties of composites are getting stronger and stronger. The results show that when the CF/C compression ratio is 1, the composites occur percolation phenomenon and dielectric constant is negative. When the CF/C compression ratio is 2, the absolute value of the negative dielectric coefficient of the EP/CF/C composite reaches 9.8 × 104, and the conductivity reaches 0.54 S/cm. In addition, impedance analysis has further confirmed that the inductance properties lead to the negative dielectric properties of the material. The adjustable negative dielectric properties of EP/CF/C composites can provide some suggestions for the field of electromagnetic shielding and capacitors.

3D hierarchical porous composites based on natural loofahs/cobalt nanoparticles/graphene oxide with efficient electromagnetic interference shielding performance

Using biomass carbon materials to construct the electromagnetic wave shielding system is an efficient solution for electromagnetic interference pollution. In this study, carbonized loofahs/Co nanoparticles/graphene oxide composites were prepared with a 3D hierarchical porous structure for efficient electromagnetic interference shielding by a facile and efficient thermal reduction process. The carbon matrix is inlaid with cobalt nanoparticles, promoting the graphitization of composites and the fabrication of a 3D conductive network. Simultaneously, the synergistic effect between nanoparticles and carbon matrix good electromagnetic properties, inducing the improvement in both dielectric and magnetic loss. As a result, the average shielding effectiveness and specific shielding effectiveness of composites reach 61.05 dB and 714.76 dB cm3/g within the frequency range of 12.4–18 GHz (Ku-band) separately, whose intense absorption loss and wideband response are superior to other composites based on biomass carbon. It is believed that this work may promote the application of biomass material in the field of electromagnetic shielding.

Prediction of the Electromagnetic Shielding Effectiveness of Metal Grid Using Neural Network Algorithm

With the advantages of simple structure, high electromagnetic (EM) shielding effectiveness (SE), wide shielding bandwidth and adjustable transmittance, the metal grid is a popular tool in the field of electromagnetic shielding. In this work, the deep learning algorithm of artificial neural network was used to predict the EM SE of the metal grid. After certain number of trainings, both the SE spectrum and the minimum SE value in a given frequency band can be predicted accurately and effectively. On the other hand, for a target SE, the design parameters of the metal grid structure can be immediately predicted. The results show that the relative mean square deviation of the predicted SE curve is about 5%, the relative error of the minimum SE value of the curve is less than 5%, and the average relative error of the minimum SE value in the predicted frequency band is 11.5%.

Lightweight MWCNT/hollow mesoporous carbon/WPU composite material with excellent electromagnetic shielding performance.

With the rapid increase of intelligent communication equipment, electromagnetic pollution is becoming more and more serious, and the research and application of high-performance electromagnetic shielding materials have attracted great attention from the academic and engineering circles. Traditional metal-based electromagnetic shielding materials have high reflection loss, high density, and are difficult to process. Polymer-based materials with carbon materials as fillers have the advantages of flexibility, light weight, corrosion resistance and low processing costs. They have become the most important materials in the field of electromagnetic shielding in recent years. However, the conductivity of conductive polymer materials is not high. Therefore, improving the electromagnetic shielding performance and the proportion of absorption loss under low density conditions have become key issues for polymer-based electromagnetic shielding materials. MWCNT/MCHMs/WPU composites were prepared by a solution mixing method, with 20 wt%, 40 wt%, 60 wt% MWCNTs and 40 wt% MWCNT/10 wt% MCHMs as fillers. By comparing the effects of different MWCNT content and MCHMs on the dielectric properties, electromagnetic shielding properties and mechanical properties of the MWCNT/MCHMs/WPU composites, the relationship between the structure and properties of the composites has been explored. The 0.6 mm WPU/60 wt% MWCNT composite has an electrical conductivity of 95.4 S m−1 and an electromagnetic shielding effectiveness of 40 dB in the X band. Adding 10 wt% MCHMs to the WPU/40 wt% MWCNT composite material can significantly improve the composite. The δ of the material increased from 51.2 S m−1 to 55.4 S m−1, and the SE increased from 30 dB to 33 dB. The research results show that the increase in MWCNT content and MCHMs is beneficial to improving the electrical conductivity and electromagnetic shielding performance of the composite materials.

Conductive waterborne silicone acrylate emulsion/carbon nanotubes composite coatings: preparation and characterization

Common organic coatings are hardly conductive and seldom applied in electromagnetic shielding fields. Thereby, the thermoplastic conductive nanocomposites, waterborne silicon-acrylic emulsion (SAE) merged with multi-walled carbon nanotubes (MWCNTs) and silica sols (Si), were prepared via co-blending method. Compared with neat SAE, the conductivity of composite latex (5 wt.% MWCNT and 1.5 wt.% Si) was raised nearly seven orders of magnitude, and the tensile strength and Young’s modulus were enhanced to 366% and 177%, respectively. The contact angle was raised from 59° to 84°. The curing temperature was decreased by 12.8 °C. These enhancements proved that the addition of MWCNTs and silica sol could boost the electrical, mechanical, curing, heatproof and waterproof performances of SAE, which will be employed in high-property conductive paint areas, including the flexible and stretchable devices.

A high-efficient tunable liquid metal-based electromagnetic absorbing metamaterial

Considerable attentions have been attracted to the implement of electromagnetic (EM) absorbing metamaterial in the past decade. Most of EM absorbing metamaterials focused on the design methods of increasing the broadband performance. However, high-efficient tunable EM absorbing metamaterials still remain a significant challenge. In this work, a 3D-printed high-efficient tunable liquid metal-based EM absorbing metamaterial was designed and demonstrated successfully. A square cavity with four gradient-depth T-shaped microchannels structure was considered as the unit cell of absorbing metamaterial. By taking advantage of the extraordinary fluidity and high conductivity of liquid metal, the high-efficient tunable capability with nearly perfect absorbance from 4.42 to 10.45 GHz and the absorbance over 95% from 3.13 to 4.44 GHz were obtained numerically and experimentally. The simulated results of absorbance agreed well with the measured ones. The designed absorbing metamaterial provides an outstanding way to achieve continuously tunable work frequency in a broadband frequency range, promoting potential application in multi-frequency microwave filters and electromagnetic shielding fields.