Thickness and Composition Tailoring of K- and Ka-Band Microwave Absorption of BaCo x Ti x Fe(12−2x)O19 Ferrites

Abstract

The goal of this research is to investigate the electromagnetic and microwave absorption properties of M-type barium hexaferrites with chemical formula BaCo x Ti x Fe (12À2x) O 19 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) in K and Ka band. Characterization techniques such as x-ray diffraction analysis and scanning electron microscopy were applied to confirm ferrite formation. The frequency dependence of the complex permittivity and complex permeability was studied for prepared ferrite samples in the frequency range from 18 GHz to 40 GHz. Factors such as the quarter-wavelength condition, impedance matching, high dielectric-magnetic losses, as well as ferromagnetic resonance were investigated to determine their contribution to the absorption characteristics. It was found that the quarter-wavelength (k/4) model could be successfully applied to predict and understand the position as well as number of reflection peaks in the microwave absorption spectrum. The origin of the reflection loss peaks is explained and verified based on calculations of input impedance, loss tangent, and ferromagnetic resonance. Reflection loss analysis revealed that all six compositions exhibited reflection loss peaks (absorption >90%) at their matching thicknesses and frequencies. Therefore, these ferrites are potential candidates for use in electromagnetic shielding applications requiring low reflectivity in K and Ka band.

Electromagnetic Wave Absorption Properties of Barium Ferrite/Reduced Graphene Oxide Nanocomposites

“…Furthermore, the RL of the sample with BaFe12O19/rGO content to epoxy of 10 wt% (sample Ι) reaches 7.39 dB at 9.5 GHz. It can be concluded from Figure 6 and RL data that the maximum absorption occurs at the frequency range in which tanδµ is higher than tanδε [45]. Table 2 summarizes microwave absorption of graphene-containing nanocomposites with different filling percents and thicknesses.…”

“…In order to reach enhanced absorption, the incidence of the EM wave on the materials should be without frontend reflection and the EM wave should also be attenuated strongly during propagation in the material. The condition of impedance matching (Zin/Z0 =1) requires equal values of relative permittivity and permeability [45]. The calculated reflection loss of the BaFe12O19/rGO/epoxy nanocomposites with barium ferrite/rGO contents to epoxy weight ratios of 10% and 20% with the sample thicknesses of 2 mm, in the range of 8.2-12.4 GHz, is shown in Figure 7.…”

Molybdenum substituted M‐type hexagonal barium ferrite for high microwave absorption performance

“…Currently, mitigating the impacts of excess electromagnetic waves has become a crucial objective due to their strong influence on the environment. [1][2][3][4] The radiation from electromagnetic waves (EMW) not only disrupts the normal functioning of electronic equipment but also poses a threat to human health. On the contrary, the rapid growth of electrical and electronic devices has resulted in an escalating demand for microwave-absorbing materials, which can be widely employed in various sectors such as industry, commerce, and defense.…”

“…Currently, mitigating the impacts of excess electromagnetic waves has become a crucial objective due to their strong influence on the environment 1–4 . The radiation from electromagnetic waves (EMW) not only disrupts the normal functioning of electronic equipment but also poses a threat to human health.…”