Microwave Absorption Bandwidth Research Articles

Fabrication of Micro‐Mesopores on Spiral Carbon Nanocoils and Simultaneous Doping with Oxygen to Expand Microwave Absorption Bandwidth

AbstractThe exceptional benefits of structural defects and doped atoms in carbon network regarding electromagnetic properties inspire the design of advanced carbon‐based microwave absorption (MA) materials. However, excessive structural defects decline the physical properties of materials, especially their conductivity. Therefore, it is a great challenge to balance structural defects and doped atoms to optimize conductive behavior for carbon‐based MA materials. The spiral carbon nanocoil (CNC), with coexisting amorphous and polycrystalline carbon structures and moderate conductivity, has significant MA properties but lacks pores and doped atoms. Herein, the amorphous carbon parts with relatively weak C─C bond energies are preferentially oxidized at 500 °C in air atmosphere to create pores and combine O atoms in the bodies of CNCs. Furthermore, the mechanism prioritizing the formation of O doping over defects is discovered. Benefiting from the synergistic interplay of structural defects and O dopants, the O‐enriched porous CNCs demonstrate enhanced conduction and polarization losses than the pure CNCs, realizing a wide effective absorption bandwidth of 7.3 GHz at a filling ratio of only 3 wt.%. Theoretical calculations further support these experimental results. The combination of structural defects and doped atoms may serve as an effective pathway for unlocking tunable dielectric properties of carbon‐based materials.

Heterointerface-engineered SnO2@SnO nanoparticle@foamed C composites for prominent microwave absorption and thermal conduction performance

The development of multifunctional materials with wide-band microwave absorption properties (MWAPs), high thermal conductivity (TC), and excellent electrical isolation is rather challenging due to the performance incompatibility. To resolve this challenge, SnO2@SnO nanoparticle(NP)@ foamed C composites are synthesized as an electrically insulated filler with low loads, excellent MWAPs, and high TC via a facile salt-template-assisted freeze-drying-annealing route. By controlling the annealing temperature (Ta) and the amount of SnCl2·2H2O (n), their heterointerfaces, textures, and defects were finely modulated. Our results show that the SnO2@SnO NP@foamed C composites have a large TC (3.48 W/(m·K); 1.5 wt% load), a minimal reflection loss (RLmin) of −40.75 dB, and an effective absorption bandwidth (EAB) of 6.88 GHz at a low load of 25 wt%. The composites exhibit an 8.0 % increase in TC, a 9.4 % increase in EAB, and an 11.0 % increase in RLmin compared with pure foamed C. Besides, the mechanism of dielectric loss and thermal transfer at the atomic level was revealed by the calculations of the density of states (DOS) and the phonon density of states (PDOS). The boosted MAWPs could be ascribed to the breakdown of local microstructural symmetry and the formation of extra electric dipoles at the interfaces of SnO/C, SnO/SnO2, and SnO2/C. The improved TC mainly results from the combined effect of the low-energy phonons from SnOx and the high-energy phonons from C. This study provides theoretical guidance for designing integrated materials with effective microwave absorption and thermal conduction in the electronic industry

In-Plane heterogeneous Structure-Boosted interfacial polarization in graphene for wide-band and wide-temperature microwave absorption

Theoretically, the strong permittivity dispersion characteristic of materials is essential for achieving broadband electromagnetic wave (EMW) absorption, which can be realized via amplified interfacial polarization effects between a dielectric phase and a lossy phase, such as by increasing the accumulated charge density in their interface area. Herein, we propose a novel strategy to boost interfacial polarization based on heterogeneous structure design in in-plane graphene (Gr) since the in-plane conductivity of Gr is significantly higher than its out-of-plane conductivity. To this end, Gr is grown on Si3N4 nanowires skeleton using chemical vapor deposition (CVD). Subsequently, Gr is controllably etched by Ni nanoparticles, and then, open graphite nanosteps are formed, which help construct in-plane heterogeneous interfaces between Gr and a dielectric phase. Such interfaces also help improve the impedance matching performance by disrupting the long-range conductive network of CVD-grown Gr. Notably, an effective absorption bandwidth of 8.48 GHz is achieved with a thickness of 2.85 mm, which is significantly wider than the EAB (5 GHz) of the out-of-plane heterogeneous structure. In addition, the in-plane heterogeneous structure also endows the EMW absorption material with excellent high-temperature insensitivity, realizing full-frequency absorption in the X-band in the 298–873 K range. This strategy to boost interfacial polarization via novel in-plane heterogeneous structure construction in Gr provides an alternative approach to explore the potential of Gr-based hybrids with planified structures to achieve wide-band and wide-temperature EMW absorption.

Based on the preparation of dual-absorber agents using Ni and Ni/rGO for the fabrication of a dual honeycomb nested structure for wideband microwave absorption

Designing absorbers with structural support to achieve ultra-wideband and wide-angle absorption properties is crucial for addressing the growing concern of electromagnetic pollution. In this study, a strategy is proposed to further broaden the bandwidth of structural absorbers by applying different materials to different structures and then nesting these different structures. Six composite materials were prepared using Ni and rGO as absorbers, and a dual honeycomb nested structure was fabricated using 3D printing technology. The minimum reflection loss (RL) of the two types of composite materials was −19.3 dB and −15.8 dB, respectively, with effective absorption bandwidths (EAB) of 4.6 GHz and 4.4 GHz, demonstrating mechanical compatibility and electromagnetic substitutability. The dual honeycomb nested structure utilized a multiscale design approach, achieving broadband absorption up to 14.27 GHz and compressive strength of 5.92 MPa. Furthermore, stable frequency response of transverse electric (TE) waves was observed within an incident angle range of 0°–40°, while absorption frequencies exceeded 12 GHz as transverse magnetic (TM) waves incident angle varied from 0° to 60°, highlighting wide-angle absorption characteristics. The dual composite preparation strategy of materials and structures for absorber fabrication provides a new perspective for further expanding the bandwidth of absorbers.

The tune of shell numbers of multi-shell hollow mesoporous carbon microspheres for enhanced microwave absorption

The morphology of carbon nanomaterials plays significant effect on the complex permittivity and microwave absorption (MA) capability. Elaborate morphology design would bring about efficient MA performance. In this work, we develop a hollow mesoporous carbon microspheres with different shells (from single to quadruple shells) through a facile template method and layer-by-layer etching process. This multi-shell hollow mesoporous carbon microspheres (MS-HMCMs) can be regarded as a complex composite morphology consisting of hollow, mesoporous and yolk-shell structure, which presents the tunable number of shells for optimal impedance matching, multiple interfacial polarization and the extended microwave transmission path from internal spaces. Thus, the MS-HMCMs demonstrates wide effective absorption bandwidth (EAB) of 6.4 GHz and 5.96 GHz at the thicknesses of 2.5 mm and 3.0 mm. Besides, the complex permittivity and MA properties can be effectively tuned via regulating the shell numbers. This MS-HMCMs with controllable shells may be a promising wideband and lightweight microwave absorber.

The Elaborate Design of Multi‐Polarization Effect by Non‐Edge Defect Strategy for Ultra‐Broad Microwave Absorption

AbstractAnion defect engineering is proven to be an efficient approach to reconstruct the electronic configuration of carbon‐based magnetoelectric materials for targeted modulation of electromagnetic (EM) performance. However, traditional mono‐anionic doping suffers from low defect concentration and lacks diverse polarization mechanisms. In this work, multi‐anions (N/S/F) stepwise‐doped carbon/Fe3C magnetoelectric composites are elaborately constructed, wherein the predesigned N defects serve as activated sites for anomalously adopting S anions (Step I) and subsequent F anions (Step II) in non‐marginal areas of the carbon layer. It is found that S prefers to replace pyrrolic N defects while F tends to form dangling bonds with the C site adjacent to the pyridinic N. Intriguingly, besides the inherent polarized resonance of N defect at ≈15 GHz, customized S and F defects induce new polarization resonances at ≈10 GHz and ≈15+ GHz, respectively. Under a typical multi‐polarization effect with the synergetic magnetic response, the carbon/Fe3C composites with N/S/F defects harvest the broadest bandwidth of 8.28 GHz (9.72–18 GHz) at 2.55 mm, covering a wide frequency range almost from X to Ku bands. This work demonstrates the positive impact of localized multi‐defects customization and multi‐polarization effect on expanding microwave absorption bandwidth, providing valuable insights for the advanced design of ultra‐broadband absorbers.

Fixed-Point Atomic Regulation Engineered Low-Thickness Wideband Microwave Absorption.

Atomic doping is widely employed to fine-tune crystal structures, energy band structures, and the corresponding electrical properties. However, due to the difficulty in precisely regulating doping sites and concentrations, establishing a relationship between electricity properties and doping becomes a huge challenge. In this work, a modulation strategy on A-site cation dopant into spinel-phase metal sulfide Co9S8 lattice via Fe and Ni elements is developed to improve the microwave absorption (MA) properties. At the atomic scale, accurately controlling doped sites can introduce local lattice distortions and strain concentration. Tunned electron energy redistribution of the doped Co9S8 strengthens electron interactions, ultimately enhancing the high-frequency dielectric polarization (ɛ' from 10.5 to 12.5 at 12GHz). For the Fe-doped Co9S8, the effective absorption bandwidth (EAB) at 1.7mm increases by 5%, and the minimum reflection loss (RLmin) improves by 26% (EAB = 5.8GHz, RLmin = -46dB). The methodology of atomic-scale fixed-point doping presents a promising avenue for customizing the dielectric properties of nanomaterials, imparting invaluable insights for the design of cutting-edge high-performance microwave absorption materials.

Hollow carbon microsphere embedded with Fe nanoparticles for broadband microwave absorption

Nowadays, Fe-based microwave absorption materials still face crucial problems of poor oxidation resistance, lack of dielectric loss and narrow effective absorption bandwidth. In this work, we developed a feasible way of calcining and etching SiO2 microspheres coated Fe3+ and polydopamine (SiO2@Fe3+-PDA) to confine Fe nanoparticles (12 nm) in the hollow carbon microspheres with a thickness of 17 nm, which provides more interfaces and polarization sites to enhance microwave attenuation. With the increase of Fe content, the microwave absorption performance of the sample is gradually improved. When Fe content is 19.7 wt%, the sample has a minimum reflection loss (RL) of −30.9 dB and a broadband absorption bandwidth (RL ≤ −10 dB) of 11.9 GHz (6.1–18 GHz) at the thickness of 4.0 mm. The ultra-wide effective absorption bandwidth is ascribed to synergetic effect of Fe nanoparticles and carbon layer, which provide magnetic loss and dielectric loss, respectively. Moreover, the hollow structure extends the transmission path and induces the multiple scattering of the incident electromagnetic waves. The novel hollow Fe/C microspheres are promising as high-efficiency microwave absorbers with strong microwave absorption and broad absorption bandwidth.

Wide-band microwave absorber with polarization insensitivity and incident angular stability using resistive ink for stealth application

A wide-band microwave absorber using five layers of resistive ink patterns is designed with a periodicity of 0.15λL, where λL denotes the wavelength at the lowest operating frequency. Symmetrically shaped resonators are patterned on five layers of FR4 substrates with air spacers between them. The fractional bandwidth of the absorber is 140% with absorption greater than 90% attained in the operating frequency range from 3.38 GHz to 19.5 GHz. Cross-polarized absorption of the structure is found to be less than 0.1%. Absorption is stable for a wide range of incident angles up to 40∘. Absorption behavior is found to be stable for both TE and TM polarized incident waves under normal incidence. Further, the mono-static radar cross-section is analyzed and found to be reduced below -40 db in the entire operating frequency.

Core-shell PCIP/NiFe2O4/PANI composite: Preparation, characterization, and applications in microwave absorption

Narrow absorption bandwidth is a common problem faced by current electromagnetic wave absorbing materials. Herein, a porous carbonyl iron/NiFe2O4/polyaniline-based wave absorbing composite material with wideband microwave absorption performance was designed by metal pitting technique, co-precipitation and in-situ polymerization. The results of SEM, XPD and XPS show that PCIP/NiFe2O4/PANI nanostructures were successfully synthesized. It is found that NiFe2O4/PANI agglomeration on the PCIP surface significantly enhances the electric loss capability of the composites. When the amount of PANI is 0.7 mL, the composite exhibits broad and strong absorbing properties, and a minimum reflection loss of −45.45 dB is obtained at 2.0 mm. The effective absorption bandwidth reaches 7.5 GHz when the matching thickness is only 2.0 mm. The synergistic effect of multiple absorbing mechanisms such as dipole polarization, interface polarization, conduction loss, natural resonance, exchange resonance and eddy current loss enables it to exhibit good wave absorption performance.

Tailorable effective microwave absorption bandwidth of chitosan-derived carbon-based aerogel under different compression

Confronted with ever-increasing electromagnetic radiation problems, developing microwave absorbing materials with tunable effective absorption bandwidth (EAB) is in high demand. In this work, chitosan-derived carbon-based aerogel was synthesized by unidirectional freeze-drying and the following high-temperature carbonization process. The dielectric-magnetic coupling effect was facilitated by the construction of the 3D conductive network, along with the decoration of the Co nanoparticles and the doping of heteroatoms within the carbon-based framework. Therefore, the aerogel achieved minimum reflection loss intensity of -44.30 dB at 5.20 GHz when carbonizing the precursor at 800 °C. More significantly, the strain-responsive properties of the aerogel endows it with tailorable electromagnetic response behaviors, thereby controlling the effective absorption bandwidth covering from X band to Ku band. This work paves the way for designing next-generation microwave absorption materials with tunable microwave absorption bandwidth, catering to stringent practical requirements prospectively.

Facile preparation and broadband microwave absorption of multilayered materials based on thin films of reduced graphene oxide

Microwave absorption (MA) materials have received extensive attention for their wide applications in both civil and military areas. However, many MA materials have a large thickness, high filling ratio, and narrow effective microwave absorption bandwidth (Reflection Loss, RL ≤ −10 dB) (EAB), and are prepared by complex processes. In this work, a reduced graphene oxide (RGO) film is prepared for the first time by an approach involving floating-dipping and chemical reduction. Compared with previous micrometers-thick RGO films, the present 200 nm-thick dense RGO film is critical for improving not only the impedance matching but also the capability of the material to attenuate incident microwaves. Based on such a thin RGO film, a multilayered material with a jaaumann structure is constructed with individual RGO layers alternating between low dielectric polyethylene terephthalate (PET) sheets. With the superb impedance matching, multilayer attenuation, and multi-cavity resonance, the present multilayered material can achieve a wide EAB of 13.75 GHz with a minimum reflection loss of −47.69 dB using only 3 layers of RGO films. This study provides a new and simple strategy for the development of layered materials with a thin thickness, low filling ratio, and strong absorption with a wide EAB.

Band gap, ferromagnetic resonance and strong microwave absorption of BaFe12-2xZnxSnxO19 compounds and enhanced dielectric loss in BaFe12-2xZnxSnxO19/carbon nano tube composites

The forbidden bandgap energy, magnetic properties, natural ferromagnetic resonance and microwave absorption are studied on the Zn2+ and Sn4+ doped BaFe12-2xZnxSnxO19. The forbidden band gap of BaFe12-2xZnxSnxO19 increases with the increasing doping content x from 1.80 eV up to 1.97 eV. The coercive field, the anisotropy field and the magnetocrystalline constant of BaFe12-2xZnxSnxO19 decreases with the increasing doping. The natural ferromagnetic resonance is observed. The high permeability, accompanied with the ferromagnetic resonance, enables strong microwave absorption. BaFe10.4Zn0.8Sn0.8O19 has a wide effective microwave absorption bandwidth (RL≤-10dB) of 6 GHz with the material thickness below 2.5 mm in 11.4–17.4 GHz. The dielectric loss has little contribution to the excellent microwave absorption of BaFe12-2xZnxSnxO19. The BaFe12-2xZnxSnxO19/carbon nanotube (CNT) composites significantly increase the permittivity. The high dielectric loss and the high magnetic loss further improve the microwave absorption. With a very thin thickness of 1.8 mm, BaFe10.4Zn0.8Sn0.8O19/CNT has a bandwidth of 7.1 + GHz of 10.9–––18 + GHz. With the material thickness thinner than 3 mm, BaFe12-2xZnxSnxO19/CNT composites have very broad effective microwave absorption bandwidth of 11.4+, 10.7 and 10.7 GHz, with x = 0.6, 0.8 and 1.0, respectively. It illustrates that both BaFe10.4Zn0.8Sn0.8O19 and BaFe12-2xZnxSnxO19/CNT composites are very promising microwave absorbers.

Lightweight and high-strength SiC/MWCNTs nanofibrous aerogel derived from RGO/MWCNTs aerogel for microwave absorption

Developing Silicon carbide (SiC) -based materials with the characteristics of “lower filling ratio, thinner matching thickness, lighter material mass, and better microwave absorption performance” is an important focus of current research. In this work, SiC/Multi-walled carbon nanotubes (MWCNTs) nanofibrous aerogel was prepared using a selective in situ derivatization strategy with Reduced Graphene Oxide (RGO)/MWCNTs aerogels as templates. It is found that when the filling ratio is only 15 %, the minimum reflection loss of the aerogel can reach −57.36 dB. When the matching thickness is only 1.5 mm, the effective microwave absorption bandwidth can reach 3.34 GHz. Moreover, the aerogel exhibits good multi-band microwave absorption performance, significantly reducing the radar cross section (RCS) in C-band, X-band, and Ku-band. In addition, the aerogel features low density and high mechanical strength, with a density as low as 0.046 g/cm3, and specific strength and specific modulus of 4.35 kN·m/kg and 12.39 kN·m/kg, respectively. This work not only provides a new synthesis strategy for the preparation of novel silicon carbide/carbon-based materials, but also contributes to the development of light-weight, high-strength and high-performance microwave absorbing materials.

Microwave absorption properties of CI and E-waste based heterogenous mixtures

This work presents the study of effect of morphology of carbonyl iron, carbonyl iron-based, and e-waste-based mixtures on microwave absorption properties. Firstly, the flake shaped carbonyl iron particles and its mixture are prepared using conventional and efficient ball milling and blending method, respectively. It provides the absorption in lower frequency region. Further, the covered frequency range starts to shifts slowly towards higher frequency ranges due to the morphological changes. On the other hand, effect of complex morphology of e-waste-based mixtures are also studied. These heterogeneous mixtures are developed using the cutting mill and blending methods that can provide the absorption in higher frequency with very narrow bandwidth. In this manner, effect of morphology on single layer microwave absorption performance of developed heterogenous material is proposed. It is also explored that the developed samples cover a wider bandwidth by utilizing the multilayering technique. A three-layer absorber is designed using genetic algorithm and the results are also validated. The structural and morphological study of the developed heterogeneous materials has been done using X-ray diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM) analysis. Also, rigorous study has been done on magnetic properties and Cole-Cole plots to understand the magnetic and dielectric losses respectively occurring inside the materials. The results showed wide bandwidth absorption of 11.62 GHz (≤−10 dB bandwidth) in the lower frequency region ranges from 0.5 to 12.12 GHz (i.e., L, C, and X-band). The total thickness achieved is 1.85 mm which is very compact (<2 mm). Thus, a thin and wideband microwave absorber at lower frequency range using heterogeneous morphology of developed materials is also presented. The proposed microwave absorbing materials can be potentially utilized for the shielding applications.

Heterogeneous structure design of Co3InC0.75/In/C derived from dual MOFs with core-shell structure for broad microwave absorption bandwidth

Metal-organic frameworks (MOFs) derivatives have attracted widespread attentions as microwave absorption materials because of their high specific surface area, low density, porous structure and easily integration with other materials. Herein, bimetallic carbides (Co3InC0.75) encapsulated into porous carbon skeletons are synthesized by the carbonization of MIL-68 (In)@ZIF-67 (Co) nanorods with core-shell structure as precursor at 800 °C. ZIF-67 (Co) dodecahedron nanoparticles are synthesized on surface of MIL-68 (In) nanorods by an in-situ synthesis at room temperature. Microwave absorption properties and mechanisms of Co3InC0.75/In/C nanocomposites with nanorods are investigated in depth. Co3InC0.75/In/C nanocomposites with nanorods structure can achieve a minimum reflection loss of −29.65 dB at 16.26 GHz under a thickness of 2.0 mm and effective absorption bandwidth of 6.89 GHz (covering X-band of electromagnetic wave) under a thickness of 2.3 mm, which can be attributed to the synergistic coactions of impedance matching, porous structure, a large amount of heterointerfaces and carbon matrix. This study sheds light on that porous carbon encapsulated by bimetallic carbides as high efficiency microwave absorption materials have a potential practical application for addressing electromagnetic radiation and pollution.

Design of Multilayer Wideband Microwave Absorbers using Improved Grey Wolf Optimizer

In this paper, an improved heuristic algorithm based on the disturbance and somersault foraging grey wolf optimizer (IDSFGWO) is proposed to optimize the design of multilayer wideband microwave absorbers for normal incidence. The multilayer absorber is designed to reduce maximum reflection coefficient by choosing suitable layers of materials from a predefined database. Three improvement strategies are given to enhance the performance of GWO, including tent map, nonlinear perturbation, and somersault foraging. The optimization results show that the reflection coefficients optimized by IDSFGWO are better than those of other algorithms for multilayer absorber design.

N atoms regulate heterogeneous crystal phase engineering of mesoporous magnetic FexN nanofibers to promote electromagnetic wave dissipation of magnetic composite aerogel absorbers

One dimensional (1D) soft magnetic nanomaterial and its lightweight porous composites are highly needed in promoting electromagnetic wave absorption for the high-frequency magnetic response and low density. In this study, lightweight magnetic composite aerogels were fabricated through the process of heterogeneous crystal phase, involving the modulation of 1D mesoporous magnetic FexN nanofibers with N atoms. The promotion of electromagnetic wave dissipation was achieved through meticulous composition design and interface optimization. The multi-mode magnetic resonance of 1D heterogeneous crystal FexN magnetic nanofibers, along with the N-doped reduced graphene/amorphous carbon three-dimensional conductive network, greatly enhances electromagnetic wave dissipation through the magnetic-dielectric synergistic effect. Consequently, the resulting composite absorber demonstrates remarkable microwave absorption capabilities, achieving a maximum effective absorption bandwidth (EABmax) of 6.63 GHz at a thickness of 2.13 mm, and a minimum reflection loss (RLmin) of −63.3 dB. In addition, the composite magnetic aerogel with the best microwave absorption performance shows a low density of 11.25 mg/cm3. This electromagnetic synergy approach is anticipated to serve as a guide for the development of highly efficient lightweight magnetoelectric composite for wideband microwave absorption in the future.

Featuring heterogeneous composite of W-type hexagonal ferrite with 2D vanadium carbide MXene for wideband microwave absorption

In this study, W-type hexagonal ferrite BaCo1.2Zn0.8Fe16O27 (BCZF) was synthesized via solid-state sintering and V2CTx-MXene was chemically etched from its V2AlC MAX phase. Subsequently, BCZF and V2CTx composites were synthesized by hydrothermal integration of V2CTx on the surface of BCZF bonded by electrostatic forces at varying mass ratios. The extensive heterostructure interfacial morphology of two dimensional V2CTx and BCZF plays an explicit role in tuning the dielectric and magnetic loss characteristics of the synthesized composites. The dielectric-magnetic synergistic loss mechanism caused by interfacial polarization, strong multi-reflections, scattering between MXene multilayer structures, conduction loss, and magnetic resonance effectively optimized impedance matching to improve the attenuation ability of the synthesized composites. Remarkably, the BCZF@10%V2CTx composite achieved strong electromagnetic wave absorption ability with an effective absorption bandwidth (RL < −10 dB) of 8.0 GHz (10–18 GHz) which is superior to that of contemporary magnetic–dielectric hybrid composites. These results present a novel perspective on magnetic V2CTx-MXene composites for microwave absorption applications, and provide a basis for the design and development of high-performance cloaking materials.

Causal optimal and optically transparent ultra-wideband microwave metamaterials absorber with high angular stability.

Wideband microwave absorbers, especially those with high optical transparency, are significantly used in civil and military fields. This paper proposes an ultra-wideband optically transparent metamaterial absorber (MMA) with causal optimal thickness and high angular stability. Based on the equivalent circuits model of the MMA, a genetic algorithm is adopted to identify the best circuit parameters that can realize broadband microwave absorption. High transparent indium tin oxide and poly-methyl methacrylate are utilized to realize the absorber. Optimization and simulation results show that the designed MMA presents a high microwave absorption above 90%, covering a wide frequency of 2.05-15.5 GHz with an impressive FBW of 153.3%. The proposed MMA exhibits extraordinary angular stability. For TM polarization, it can still maintain a fractional bandwidth (FBW) over 114.5% at an incidence angle of 70° and over 142% at an incidence angle of 60°, while the FBW of both TE polarization and TM polarization exceeds 150% when the incidence angle is below 45°. Furthermore, the proposed absorber has the advantages of high transparency and polarization insensitiveness. A prototype of the proposed MMA is fabricated and experimentally tested. The measured results are in excellent agreement with the optimized design and the full-wave simulation results, demonstrating its excellent performance. Most significantly, the overall thickness of the absorber is 0.102 λ at the lowest working frequency and only 1.08 times the causality-dictated minimum sample thickness. The MMA proposed herein provides methods to achieve high compatibility with wideband microwave absorption, optical transparency, and wide-angle incidence, thus enabling a wide range of applications in stealth, electromagnetic pollution reduction, and electromagnetic compatible facilities.