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The article discusses the electromagnetic absorbing and shielding properties of ferrite-polymer composites of the composition Mn-Zn ferrite/fluoroplast-42, obtained by pressing a mixture of powders with heating. The measurement of the complex magnetic and dielectric permittivity spectra, as well as the reflection coefficient spectra was carried out in the frequency range 0.1-7 GHz. Using the obtained spectra, a comprehensive analysis of the absorbing characteristics of the composites was carried out, and the factors responsible for the absorption were determined. Fitting of the composites magnetic permeability spectra show that the process of natural ferromagnetic resonance prevails over the resonance of domain walls, and a decrease in the concentration of ferrite inclusions leads to a significant shift in the frequency of natural ferromagnetic resonance to high frequencies. It was found that for composites with a thickness of 5-10 mm, compositions with a mass fraction of ferrite ≤0.4 show radio-absorbing properties, while compositions with a fraction of ≥0.6 show shielding properties. Keywords: polymer composite, magnetic properties, radio absorption, feromagnetic resonance, polyvinylidene fluoride, manganese-zinc ferrite.

The electromagnetic and radio-absorbing characteristics offerrite-polymer composites with conductive inclusions based on polyvinylalcohol are investigated. The Ni-Zn spinel ferrite powder of 2000NN gradewith composition Ni0.32Zn0.68Fe2O4 was used as filler. It is shown that theobtained composites are effective absorbers in the frequency range of 2-5 GHz with peak reflection loss less than ~20 dB. Through the analysis of thepermittivity spectra and permeability spectra, as well as the calculatedreflection loss spectra, critical factors of the electromagnetic waveabsorption in obtained composites are established. Keywords: polymer composite, radio absorption, nickel-zinc ferrite,polyvinyl alcohol\

The article describes electromagnetic and microwave properties of the polymer composite with the lithium spinel ferrite inclusion of composition Li0.33Fe2.29Zn0.21Mn0.17O4 in the frequency range 100-7000 MHz. It is shown that samples with a mass fraction of ferrite 60, 80% have pronounced radio-absorbing properties, measured using the reflection coefficient on a metal plate (return losses). For a composite with 80% ferrite, the minimum return loss was -37.5 dB at 2.71 GHz with an absorption width at -10 dB of 3 GHz. High absorption characteristics are directly related to the use of ferroelectric polymer P(VDF-TFE) as a binder, which is expressed in the combined action of the absorption mechanisms of the magnetic and ferroelectric phases. Keywords: lithium ferrite, polymer composite, polyvinylidene fluoride, radio-absorbing material.