Due to the widespread use of microwave electromagnetic radiation, this study examines the microwave electromagnetic properties and compressive strength of composites made from inexpensive components such as Mg_0.5Zn_0.5Fe₂O₄, polystyrene, and activated carbon. Experimental samples were fabricated using thermopressing. The formation of the dielectric core/shell structure for Mg-Zn/polystyrene composites (1:1) and composites with activated carbon additives at weight concentrations of 3, 6.6, and 9.0% was determined using SEM image analysis. Microwave properties were investigated by analyzing the frequency dependences of complex permittivity and magnetic permeability in the frequency range of 100 MHz–5 GHz. As shown by the simulation and experimental measurements of scattering parameters obtained, the compost shows improved microwave absorption properties in the frequency range of 1–5 GHz. Reflection loss spectra showed peaks with values of −17.8 and −18 dB in the frequency range of 2.5–5 GHz for samples with 4.8 wt. % and 6.6 wt. % carbon loading, respectively. The absorption bandwidths of −10 dB in the range of 1.7–2.13 GHz were observed in the best samples. Studies have shown that samples containing 9.0 wt. % of carbon material with thicknesses of 6–10 mm can be considered as an electromagnetic shielding material in the microwave range 1–5 GHz. It was shown that, despite a decrease in porosity from 15.59 to 7.17%, with an increase in the concentration of carbon material in the composites, the compressive strength also decreases from 62.05 to 36.45 MPa. The developed composites are potentially suitable as microwave absorbers for civil applications.

The experimental data of the elastic scattering process of the 9Ве+12С nuclear system were analyzed from the point of view of microscopic theory in energy near the Coulomb barrier. The new Botswana 3-Yukawa -Fetal potential, created in a variational approach with lower-order constraints on two body matrices, was first used for the 9Ве+12С system as a real part of the optical potential. In the double folding model, density-dependent parameters were introduced into the nucleon density distribution formula, and they were applied to the Botswana 3-Yukawa - Fetal and Michigan 3-Yukawa - Paris potentials based on effective nucleon-nucleon interactions. As a result, modified real microfolding potentials were created. The results of a semi-microscopic analysis calculated on the basis of new microfolding potentials were presented. The uniqueness of the research lies in the calculation of density-dependent parameters based on the incompressibility coefficient, which characterizes the saturation properties of the nuclear medium. The equations of state of the elastic scattering process were formulated at the saturation density (ρ0=0.17 fm-3), determined from the density dependence of the nuclear binding energy. The analysis results allow for a more accurate determination of nuclear properties and enhance the saturation properties of the nuclear medium. The efficiency of the new real potential was determined from a microscopic perspective, and the optimal parameters of the optical potential were found.

In this work, titanium oxynitride films were obtained on the surface of glass and silicon substrates by magnetron sputtering in a mixture of argon-oxygen-nitrogen gases. The thickness of the obtained films, their deposition rate, and surface morphology were estimated depending on the type of substrate. The optical and electrical properties of films produced on the glass surface have been studied. A comparison of optical data with literature data showed the formation of amorphous films with a composition close to the stoichiometric composition of TiO1.27N0.49. The results showed that the obtained properties correspond to the literature data, which opens up new prospects for the use of the obtained titanium oxynitride films as an active element of memristors, and in other important areas of modern materials science.

This paper presents the research and development results of circularly polarised antennas used in radio frequency identification (RFID) systems. Such antennas play a crucial role in improving reliability, orientation independence and reading range of RFID systems in industry, transport and logistics. The frequency range under consideration is 860-900 MHz (UHF), which is widely used for passive RFID technologies due to its favorable propagation characteristics and compatibility with international standards. A printed antenna from FEIG ELECTRONIC GmbH (Germany) was used as a reference for the developed antenna. This paper presents the results of a similar antenna but without the use of a symmetry transformer. The elimination of this component reduces the overall design complexity, improves manufacturability and minimizes manufacturing cost, making the design more suitable for mass deployment. The printed dipole was developed on a 1.6 mm thick FR4 substrate with a relative dielectric constant of 4.3 and a dielectric loss tangent of 0.02. The dimensions of the developed printed dipole correspond to 332 mm × 34 mm × 1.6 mm. The printed dipole and the overall design of the developed RFID antenna were pre-simulated in the software environment “CST Studio Suite”, which allows accurate simulation of the electromagnetic behavior. This modelling step was necessary to optimize the input matching, radiation efficiency and circular polarization characteristics. The frequency of the designed antenna was 868 MHz (|S11| < -10 dB). and the radiated power was measured to be -11.7 dBm. The layout of the printed dipole was designed using Altium Designer software. The prototype assembly proceeded following model-based and electromagnetic simulation techniques. A Spectrum Rider FPH spectrum analyzer conducted test measurements which supported the theoretical prediction results. The proposed framework demonstrates great promise as an inexpensive solution with high detection efficiency for modern RFID systems operating in diverse conditions.

Often, when describing the electromagnetic properties of polymer composites in the microwave range, little attention is paid to magnetic spectra and the description of their features using known dispersion models. In this paper, we investigate the microstructure and frequency spectra of the complex permittivity and complex permeability of the ferrite-polymer composite PVDF/Ni_0.4Zn_0.6Fe₂O₄ in the frequency range of 100 MHz–5 GHz and a mass concentration of 10–80 wt.%. The composite structure was investigated by scanning electron microscopy, while the frequency dependences of permittivity and magnetic permeability were measured using a vector network analyzer together with the Nicholson–Ross–Weir method. In the course of the work, using the fitting of the experimental spectra by known models of natural ferromagnetic resonance and domain wall resonance, the features of the dispersion of the magnetic spectra were explained. In particular, the shift of resonance frequency and the dominant contribution of spin rotation to the permeability value were interpreted using the results of fitting. In addition, comparison of the features of the reflection loss spectra and the results of model fitting helped to identify the main contribution of the spin rotation process to the attenuation of the electromagnetic wave in composites. The results obtained in the work are relevant for the development of new approaches to predicting the electromagnetic characteristics of composites using effective medium models.

Актуальными являются экспериментальные исследования по получению частотных зависимостей диэлектрической проницаемости термопластов в микроволновом диапазоне, ввиду их использования в качестве матриц дисперсно-наполненных композитов. Целью настоящей работы является подбор технологических параметров для получения монолитных образцов некоторых широко используемых термопластов и измерение частотной зависимости комплексной диэлектрической проницаемости в диапазоне 100 МГц – 5 ГГц. В качестве объектов исследования были использованы поливинилиденфторид, фторкаучук поли(трифторхлорэтилен-винилиденфторид), поливиниловый спирт и полистирол. Образцы изготавливались методом горячего прессования на экспериментальном стенде при индивидуально подобранных значениях температуры выдержки, рабочего давления и времени выдержки, обеспечивающих получение монолитных изделий без визуально наблюдаемой пористости и внутренних дефектов. Частотные спектры комплексной диэлектрической проницаемости были измерены с помощью метода Николсона-Росса-Вира при комнатной температуре с использованием векторного анализатора цепей. В ходе проведения экспериментов обнаружено, что режимы термопрессования для используемых термопластов существенно различаются. При получении колец из поливинилового спирта наблюдалось пожелтение образцов, предположительно связанное с начальными стадиями термической деструкции материала. В диапазоне частот 100 МГц–5 ГГц действительная часть диэлектрической проницаемости ε’ для поливнилиденфторида составила 2,57–3,31, для фторкаучука — 2,40–3,16, для поливинилового спирта — 3,61–4,63. В случае полистирола значение ε’ в исследуемом диапазоне составило 2.64. Для всех полимеров кроме полистирола обнаружена выраженная частотная дисперсия комплексной диэлектрической проницаемости, а также диэлектрические потери в диапазоне 0,05–0,20. Помимо этого, рассчитанное значение коэффициента отражения на металлической пластине составляло от –4 до –2,5 дБ для термопластов с выраженными диэлектрическими потерями. Полученные частотные зависимости дополняют сведения о диэлектрических характеристиках распространенных термопластов в микроволновом диапазоне частот и могут быть использованы при разработке полимерных композиционных материалов с заданными диэлектрическими характеристиками для изделий радиоэлектроники, СВЧ-техники и радиопоглощающих материалов.