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- MakaleAçık Erişim2025Scopus SJRQ2High-Performance Microwave-Absorbing Hemp Textile: Ni-Zn Ferrite and Multiwalled Carbon Nanotubes-Infused Nanocomposite for X-Band Electromagnetic Interference Shielding
Teber, Pembe; Teber, Ahmet; Karakaş, İbrahim Hakkı
This study aims to develop a flexible and sustainable electromagnetic (EM) wave-absorbing material by using hemp fabric as a substrate incorporated with multiwalled carbon nanotubes (MWCNTs) and magnetic Ni-Zn ferrite nanoparticles (NPs). In this context, the objective is to achieve effective EM attenuation across a wide frequency range using a green, lightweight composite to meet the rising demand for ecofriendly shielding in electronic and communication systems. Ni0.5Zn0.5Fe2O4 and MWCNT composite NPs are uniformly dispersed in a molten paraffin binder and impregnated into hemp fabrics. The magnetic NPs are synthesized via the microwave-assisted combustion method. The EM parameters of the resulting structure are determined in the X-band using experimental scattering data and the Nicholson–Ross–Weir method. Absorption performance is evaluated based on varying weight ratios of magnetic NPs and MWCNTs, with an emphasis on impedance matching. The results indicate that combining dielectric and magnetic components significantly enhances absorption. A maximum reflection loss of −72.42 dB and a 3.81 GHz bandwidth (covering over 90.71% of the X-band) are achieved at 10.08 GHz. Increasing Ni-Zn content shifts the resonance to higher frequencies. This sustainable, flexible composite shows strong potential for electromagnetic interference shielding, particularly in defense applications requiring radar invisibility.
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İncele - MakaleAçık Erişim2021Scopus SJRQ1Effect of sample deformation in longitudinal axis on material parameter extraction by waveguides
Hasar, Ugur Cem; Kaya, Yunus; Ozturk, Gokhan; Ertugrul, Mehmet
An analysis was performed for examining the consequences of sample deformation in longitudinal axis in the sample-loaded non-resonant waveguide techniques. Vertical and horizontal deformations were first simulated to understand the change in field distributions and corresponding scattering parameters. Then, effects of sample length, dielectric constant, and loss factor for these deformations on extracted electromagnetic properties were analyzed using simulated results. Finally, S-parameter measurements were carried out to understand the effect of vertical deformation on permittivity results and to examine any improper sample preparation by hand-made and machine-made samples by applying a statistical model based on mean, standard deviation, coefficient of variation, and confidence interval. It was noted that extracted dielectric constants of each tested dielectric sample (polyethylene, polypropylene, polyvinyl-chloride) were within the confidence interval range of 90% while their retrieved loss factors were within the confidence interval range of 90%, 95%, or 98%.
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