High-temperature microwave absorbing materials (MAMs) and structures are increasingly appealing due to their critical role in stealth applications under harsh environments. However, the impedance mismatch caused by increased conduction loss often leads to a significant decline in electromagnetic wave absorption (EMWA) performance at elevated temperatures, which severely restricts their practical application. In this study, we propose a novel approach for efficient electromagnetic wave absorption across a wide temperature range using reduced graphene oxide (RGO)/epoxy resin (EP) metacomposites that integrate both electromagnetic parameters and metamaterial design concepts. Due to the discrete distribution of the units, electromagnetic waves can more easily penetrate the interior of materials, thereby exhibiting stable microwave absorption (MA) performance and impedance-matching characteristics suitable across a wide temperature range. Consequently, exceptional MA properties can be achieved within the temperature range from 298 to 473 K. Furthermore, by carefully controlling the structural parameters in RGO metacomposites, both the resonant frequency and effective absorption bandwidth (EAB) can be optimized based on precise manipulation of equivalent electromagnetic parameters. This study not only provides an effective approach for the rational design of MA performance but also offers novel insights into achieving super metamaterials with outstanding performance across a wide temperature spectrum.

In this paper, a novel dual-band wideband bandpass filter (BPF) based on transversal signal-interaction concepts with a wide upper stopband is proposed and investigated. The designed specification of two passbands can be managed and satisfied based on the independent controllable fractional bandwidth of the two passbands and the centered frequencies. The centered frequencies of dual-band BPF are, respectively, 0.79 GHz (f(1)) and 1.24 GHz (f(2)) with 3 dB fraction bandwidths of 26.54% and 11.3%. Two transmission paths consisting of coupled stub-loaded square ring resonators and anti-coupled shorted lines are used to realize signal cancellation of multiple transmission path signal transmission from Port 1 to Port 2. Eleven transmission zeros (TZs) modify harmonic suppression up to 10 f(1) with stopband rejection higher than 15 dB. Butterworth lumped notch network and step impedance resonator (SIR) are also utilized to improve the selectivity and harmonic suppression. A compact filter with a circuit size of 0.08 lambda g x 0.08 lambda g is implemented and tested. Good agreement between simulation and measured results verifies the reliability of the designing scheme.

Currently, the microwave absorbers usually suffer dreadful electromagnetic wave absorption (EMWA) performance damping at elevated temperature due to impedance mismatching induced by increased conduction loss. Consequently, the development of high-performance EMWA materials with good impedance matching and strong loss ability in wide temperature spectrum has emerged as a top priority. Herein, due to the high melting point, good electrical conductivity, excellent environmental stability, EM coupling effect, and abundant interfaces of titanium nitride (TiN) nanotubes, they were designed based on the controlling kinetic diffusion procedure and Ostwald ripening process. Benefiting from boosted heterogeneous interfaces between TiN nanotubes and polydimethylsiloxane (PDMS), enhanced polarization loss relaxations were created, which could not only improve the depletion efficiency of EMWA, but also contribute to the optimized impedance matching at elevated temperature. Therefore, the TiN nanotubes/PDMS composite showed excellent EMWA performances at varied temperature (298–573 K), while achieved an effective absorption bandwidth (EAB) value of 3.23 GHz and a minimum reflection loss (RLmin) value of − 44.15 dB at 423 K. This study not only clarifies the relationship between dielectric loss capacity (conduction loss and polarization loss) and temperature, but also breaks new ground for EM absorbers in wide temperature spectrum based on interface engineering.

In light of the three primary challenges faced by transparent conductive coatings, namely poor conductivity, elevated filler content, and insufficient visible light transmittance, chain-like conductive fillers due to the unique morphology and structure have been developed to address these concerns simultaneously. A straightforward synthesis of antimony-doped tin oxide (ATO) nanochains was accomplished through a simple two-step coprecipitation and hydrothermal methods. Firstly, an antimony-doped stannic hydroxide hydrogel precursor was generated through coprecipitation. Secondly, by adjusting the pH value in the hydrothermal reaction, one-dimensional chain ATO nanocrystals were obtained without the need for additional materials. The synthesized ATO, with a chain-like morphology, comprises particles of approximately 3-5 nm in diameter and 2-5 µm in length. Throughout the reaction, ammonium hydroxide, used as a pH regulator, played a vital role as a reducing agent in forming ATO nanochains without the need for further post-treatment. Moreover, chain-like ATO compounded with SiO2 transparent conductive coatings exhibited exceptional transparent conductive properties, with a visible-light transmittance of approximately 84.7% at the wavelength of 550 nm and a block resistance of 0.5 kΩ/□ upon spin-coating deposition on glass. This remarkable performance can be attributed to the generation of a continuous conductive network, induced by the distinctive chain-like morphology. The approach for the preparation of ATO nanochains was simple and easy to scale up, hopefully, to provide an enormous potential and broad prospect for the application of chain-like ATO in antistatic property.

In light of the three primary challenges faced by transparent conductive coatings, namely poor conductivity, elevated the active substance content, and insufficient visible light transmittance, net-like conductive agents due to the unique morphology and structure have been developed to address these concerns simultaneously. A straightforward synthesis of antimony-doped tin oxide (ATO) nanonets was accomplished through a simple two-step coprecipitation and hydrothermal methods. Firstly, an antimony-doped stannic hydroxide hydrogel precursor was generated through coprecipitation. Secondly, by adjusting the pH value in the hydrothermal reaction, ATO nanocrystals network were obtained without the need for additional materials. The synthesized ATO, with a net-like morphology, comprises particles of approximately 3-5 nm in diameter. Throughout the reaction, ammonium hydroxide, used as a pH regulator, played a vital role as a reducing agent in forming ATO nanonets without the need for further post-treatment. Moreover, net-like ATO compounded with SiO2 transparent conductive coatings exhibited exceptional transparent conductive properties, with a visible-light transmittance of approximately 84.7% at the wavelength of 550 nm and a square resistance of 0.5 kΩ/sq upon spin-coating deposition on glass. This remarkable performance can be attributed to the generation of a continuous conductive network. In comparison to granular ATO, the network structure ATO nanocrystal showcases a significant improvement in resistivity, demonstrating its exemplary transparent conductivity. The approach for the preparation of ATO nanonets was simple and easy to scale up to provide an enormous potential and broad prospect for the application of net-like ATO in transparent conductive coating.

Simultaneous development of well impedance matching and strong loss capability has become a mainstream method for achieving outstanding electromagnetic microwave absorption (EMWA) performances over wide temperature range. However, it is difficult to pursue both due to the mutual restraint of relationship between impedance matching and loss capability about temperature. Here, we propose a flexible regulation engineering of titanium nitride (TiN) nanofibrous membranes (NMs, TNMs), which could be distributed uniformly in the polydimethylsiloxane (PDMS) matrix and contributed to the formation of abundant local conductive networks, generating the local conductive loss and enhancing the loss ability of EMWs. Moreover, when the TNMs are used as functional units and dispersed in the matrix, the corresponding composites exhibit an outstanding anti-reflection effect on microwaves. As hoped, under the precondition of good impedance matching, local conductive loss and polarization loss together improve the loss capacity at room temperature, and polarization loss can compensate the local conductive loss to acquire effective dielectric response at elevated temperature. Benefiting from the reasonably synergistic loss ability caused by flexible regulation engineering, the corresponding composites exhibit the perfect EMWA performances in a wide temperature range from 298 to 573 K. This work not only elaborates the ponderable insights of independent membrane in the composition-structure-function connection, but also provides a feasible tactic for resolving coexistence of well impedance matching and strong loss capability issues in wide temperature spectrum.

Due to the temperature and frequency response of electromagnetic (EM) loss, how to realize the effective design of microwave absorption materials (MWAMs) at elevated temperature is highly desirable for practical applications. Herein, transition metal-doped titanium nitride (M-TiN, M = Fe or Co) fibers were fabricated, the distortion of TiN lattice could cause the adjustable charge enrichment, which played a profound influence on the dielectric response and EM microwave absorption (EMWA) performances. Benefiting from the negative correlation between dielectric loss and temperature, more loss mechanism could be introduced, which would effectively enhance dielectric loss and EMWA performances at elevated temperature. The optimal EMWA performances of Fe-TiN fibers/polydimethylsiloxane (PDMS) composites were realized with a wide temperature range (298–423 K): the reflection loss (RL) could reach 99