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Manipulation of electromagnetic (EM) waves is essential for various microwave applications. This research studies the modulation of EM waves by using single-layer plasma arrays consisting of discharge tubes. We experimentally investigate the transmission spectra and backscattering attenuation characteristics of the plasma arrays, and numerical simulations further reveal the modulation mechanism and influences of the plasma arrays. The experimental and numerical results show that broadband tunable photonic bandgaps can be achieved in frequency ranges of 4–7.5 GHz and 7–9.5 GHz for the transmission spectrum and the backscattering spectrum, respectively. In addition, the proposed plasma array can achieve different modulation effects to satisfy the corresponding scenario requirements by adjusting the configuration and parameters such as the plasma frequency, spacing of the plasma tubes, and the discharge tube’s excitation or extinction of the plasma array. The wave manipulation of the combined plasma array creates opportunities for developing numerous applications, including large-area spatial filtering, radar stealth, and reconfigurable antennas.

Carbon−based carbides have attracted tremendous attention for electromagnetic energy attenuation due to their adjustable dielectric properties, oxidation resistance, and good chemical stability. Herein, we reasonably regulate the growth of dopamine hydrochloride on the surface of the Mo−glycerate (Mo−GL) microsphere and then transform the resultant Mo−polydopamine (Mo−PD) microsphere into a dual−shell Mo2C/C (DS−Mo2C/C) microsphere in a high−temperature pyrolysis process under an inert atmosphere. It is found that the pyrolysis temperature plays an important role in the graphitization degree of the carbon matrix and internal architecture. The fabrication of a dual−shell structure can be propitious to the optimization of impedance matching, and the introduction of Mo2C nanoparticles also prompts the accumulation of polarization loss. When the pyrolysis temperature reaches 800 °C, the optimized composite of DS−Mo2C/C−800 exhibits good EM absorption performance in the frequency range of 2.0–18.0 GHz. DS−Mo2C/C−800′s qualified bandwidth can reach 4.4 GHz at a matching thickness of 1.5 mm, and the integrated qualified bandwidth (QBW) even exceeds 14.5 GHz with a thickness range of 1.5–5.0 mm. The positive effects of the dual−shell structure and Mo2C nanoparticles on EM energy attenuation may render the DS−Mo2C/C microsphere as a promising candidate for lightweight and broad bandwidth EM absorption materials in the future.

Manipulation of electromagnetic waves is essential to various microwave applications, and absorbing devices composed of low-pressure gas discharge tubes and radar-absorbing materials (RAM) can bring new solutions to broadband electromagnetic stealth. The microwave transmission method is used to measure the physical parameters of the plasma unit. The designed structure exhibits superior absorption performance and radar cross-section (RCS) reduction capability in the 2-18 GHz band, with unique absorption advantages in the S/C frequency band. It is found that the combination of the plasma and the RAM can significantly broaden the absorption frequency band and improve the absorption performance with excellent synergistic stealth capability. Experimental and simulation results show that broadband, wide-angle, tunable electromagnetic wave absorption and RCS reduction can be achieved by adjusting the spatial layout of the combined plasma layer and the type of RAMs, which creates opportunities for microwave transmission and selective stealth of equipment. Therefore, the wave manipulation by combined plasma array and RAM provides a valuable reference for developing numerous applications, including radar antenna stealth, spatial filter, and high power microwave shielding.

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