Multifunctional Metamaterial Microwave Blackbody with High‐Frequency Compatibility, Temperature Insensitivity, and Structural Scalability

Abstract

Compared with optical black, few attempts have focused on achieving broadband microwave blackbodies. In this study, all‐ceramic metamaterial microwave blackbodies are created by integrating a graded Gyroid shellular (GGS) metastructure design with additive manufacturing of polymer‐derived SiOC (PDCs‐SiOC) ceramics encapsulated by Si3N4 (SiOC@Si3N4). Hardly influenced by the destructive interference effect, as‐fabricated GGS‐structured SiOC@Si3N4 microwave blackbodies demonstrate a broadband microwave absorption (MA) above 83.6% (91.3% on average) across the entire X‐Ku band and encompassing higher frequencies above 18 GHz as well, together with the temperature insensitivity from room temperature to 500 °C. Based on the flexible electromagnetic tunability of PDCs‐SiOC, exceptional structural scalability is experimentally validated for metal‐doped modified CuSiOC and CoSiOC substrates with the same GGS metastructures, retaining high‐efficiency MA capability. Furthermore, attachment of perfectly reflecting metal backplanes further enhances the MA performance, with an ultrawide MA exceeding 67.9% (89.1% on average) achievable at 2.95–18 GHz for CoSiOC substrate. Meanwhile, the GGS‐structured SiOC@Si3N4 metamaterials possess additional multifunctional properties, such as good noise reduction performance as well as ultrahigh wear resistance. As a proof of concept, this study provides important guidance on achieving multifunctional coupling broadband MA characteristics by fully tapping the application potential of existing materials.

Microwave absorbing characteristics of porphyrin derivates: a loop of conjugated structure

“…On the one hand, the charge circuits and electron hopping generating the conductive loops establish secondary elds on the other hand quadrupole polarization originating from the presence of the electronegative elements in the conjugated rings can act as quasi-antenna inducing the secondary currents, denoted by Oersted's and Lenz's law. 38,42,44,56,84,85,[96][97][98][99][100] The produced vortexes interact with the inputted microwaves and create permeability and negative parts. The regulated permeability and permittivity ratify the penetration of the incident waves, described by impedance matching (Z).…”

Structural Electromagnetic Absorber Based on MoS2/PyC‐Al2O3 Ceramic Metamaterials

“…The fast development of electronic devices and the widespread use of wireless communication technologies led to a tremendous increase in electromagnetic radiation (EMR) in our environment. [1][2][3][4] Advanced structural EM absorption materials (EMAM) possessing not only ultra-broad effective absorption bandwidth (EAB) ≥ 30 GHz but also outstanding mechanical strength, especially under harsh environments (e.g., elevated temperature, corrosive media), are playing an increasingly important role in combating the effects of EMR. [5,6] Currently, polymer-based materials, and advanced carbon-and MXenebased lightweight structures (e.g., foams and gels) are the most frequently reported EM absorption materials due to their easy processability, lightweight and flexibility.…”

“…Due to the difficulties in creating complex meta-structures via traditional shaping methods (e.g., casting, molding, and machining), progress in creating ceramic-based EM metamaterials began with the use of additive manufacturing (AM) techniques. [4,29] Reports show that the fabrication of meta-structures via AM led to a considerable increase in EAB compared to the same materials in monolithic form. However, limited by the aforementioned absorbent types as well as the challenges in engineering nanostructures by the state-of-the-art AM techniques, the EM absorption performance of current ceramic-based EM metamaterials is still not satisfying.…”

“…However, limited by the aforementioned absorbent types as well as the challenges in engineering nanostructures by the state-of-the-art AM techniques, the EM absorption performance of current ceramic-based EM metamaterials is still not satisfying. [4,29,34] Moreover, due to the high residual porosity and/ or cracks formed during sintering or pyrolysis, ceramic components shaped via AM techniques often exhibit poor mechanical strength. [35,36] Therefore, a breakthrough in structural EM absorption metamaterials based on ceramics has not been achieved up to now, due to the limitations in the type of materials, systems as well as the (micro)structure of the absorbents.…”

Wide-temperature-range multispectral camouflage enabled by orientation-gradient co-optimized microwave blackbody metastructure coupled with conformal MXene coating

“…Indeed, the camouflage technology should possess the following characteristics: (i) high absorption of Vis light (380-780 nm) and 1.06 mm lasers for camouflage under a dark environment and against near-infrared (NIR) lidars; 4,5 (ii) low IR emittance (high reflection) in the atmospheric window, including the mid-wavelength IR (MWIR, wavelength 3-5 mm) and long-wavelength IR (LWIR, wavelength 8-14 mm) range for camouflage against thermal imaging systems; 2,6 and (iii) high absorption of MWs (e.g., the X-Ku band, 1.67-3.66 cm) for camouflage against MW radar detection. 7 Fortunately, emerging artificial metamaterials with tailorable electromagnetic properties via flexible subwavelength structure design offer a new approach to achieving multispectral camouflage. A widely adopted strategy is constructing hierarchical multimaterial laminate architectures, e.g., photonic crystals 4,8,9 and stacked metamaterials/ metasurfaces, 1-3,10-12 with feature sizes ranging from nanometers to millimeters.…”