A method for enhancing the adhesion properties of polytetrafluoroethylene (PTFE) surfaces is presented. The approach employs a fast neutrals flow generated by a DC glow discharge plasma with a grid neutralizer. Low power levels (≈6 W) provided by the stable DC discharge prevent physical sputtering and surface damage, while strong UV radiation from pure argon promotes efficient defluorination. The choice of working gas composition, discharge parameters, and treatment duration was informed by plasma emission spectroscopy, water contact angle (WCA) measurements, and systematic optimization. The combined effect of low-energy neutral particles and UV radiation leads to a significant increase in surface energy to 82 mN/m and a reduction in WCA to 13°, confirming the effectiveness of the proposed method. Thanks to its simplicity, scalability, and reliability, the method holds significant potential for industrial applications.

Introduction. In view of the ever-tightening bandwidth requirements for wireless communication systems, the use of tunable or switching devices based on microwave keys is becoming increasingly popular. Currently, the development of microwave keys based on nonlinear materials, such as vanadium dioxide, is a relevant research direction. The keys based on this material are distinguished by a planar and simple design, thus being suitable for creating microwave devices using hybrid technology.Aim. To study the properties of thin vanadium dioxide films and to develop a microwave switch with electrical switching on their basis.Materials and methods. Experimental samples of thin vanadium dioxide films were obtained by magnetron sputtering. The phase transition parameters of the samples obtained experimentally were used in computer simulation of a planar two-electrode structure of a microwave key by the finite element method.Results. Experimental samples of vanadium dioxide films were manufactured, and the dependences of their resistivity on temperature were studied. The resistance of the obtained vanadium dioxide films was found to change threefold. A microwave key design based on vanadium dioxide films was developed. The formation of a currentconducting channel in vanadium dioxide films was simulated when a control voltage was applied. The threshold voltage of the element was estimated depending on its design parameters.Conclusion. The use of experimental data as a basis for computer simulation made it possible to determine the threshold values of currents depending on the topology and design of the proposed microwave key. The results of simulating the key structure showed the formed conductive channel to have clearly defined boundaries in terms of distribution of both current density and temperature across the film surface.

A fast-neutral flux generated from a glow gas discharge using a custom-designed source has been proposed to improve the adhesion of PTFE surfaces. The effects of glow discharge parameters and the composition of the working gas on the activation process were evaluated through contact angle measurements and subsequent surface energy calculations. PTFE surfaces treated in an argon atmosphere exhibited the most significant hydrophilic and adhesive properties, achieving a water contact angle as low as 13∘ and surface energy values of 82 mN/m, with an exceptionally high polar component. The optimal effect was observed when the optical spectrum of the plasma showed maximum intensity peaks in the UV range at wavelengths between 310 and 315 nm. The outcomes of this proposed method were then compared with those obtained using conventional industrial techniques for enhancing adhesion.

Introduction. The development of telecommunication networks and radar systems operating in the 10…100 GHz range requires materials with low dielectric permittivity (ε less than two). Additive technologies, such as digital light processing (DLP), are promising for fabrication of 3D devices; however, controlling air void distribution in photopolymers remains challenging due to their rheological properties. This paper proposes an approach for developing a composite material based on a photopolymer matrix and hollow glass microspheres (HGM) aimed at reducing the effective permittivity of the material. Aim. To study approaches for obtaining a mixture of a photopolymer binder and HGM and to compare the microwave parameters of samples obtained by layer-by-layer photocuring and polymerization from a suspension, to achieve ε less than two. Materials and methods. The effective permittivity was calculated using the finite element method in both electrostatic and electrodynamic (10 GHz) modes. The Anycubic Clear transparent photopolymer resin was used as the composite matrix, and hollow silicon dioxide microspheres with an average particle size of about 50 μm were used as the filler. Electrophysical parameters were measured using a Ceyear 3272C vector network analyzer. Results. A mixture recycling system for DLP printers is developed, enabling the production of composites with a low filler volume fraction. The 5.5:1 mixture of photopolymer and HGM reduced permittivity by 10% compared to the unfilled photopolymer. The preparation of an HGM suspension in the resin volume made it possible to significantly increase the filler content, which led to a 40 % reduction in permittivity. Conclusion. The use of a suspension reduces the dielectric constant from 2.9 to 1.75, corresponding to a 40 % decrease. The developed recirculation system is compatible with commercial 3D printers and enables the fabrication of samples with low HGM concentrations (up to 5…7 %).

Introduction. The ever-increasing demands on the speed of information transmission lead to an increasing adoption of MIMO systems in telecommunication networks. There are a number of works devoted to the possibility of using MIMO antenna modules based on SIW resonators. One of the promising directions in this field is the use of 1/4 and 1/8 mode SIW resonators, which can significantly reduce the weight and size characteristics of the device. The main disadvantages of such MIMO antennas are the narrow frequency band and a relatively low isolation of the radiators. Therefore, the advancement of engineering approaches to designing MIMO modules that boost these attributes is a relevant research task.Aim. Development of innovative engineering approaches to designing antenna modules utilizing 1/8 mode SIW resonators for application in MIMO, which enhance their radiation properties and improve the isolation between the radiators.Materials and methods. The characteristics of the antenna module were simulated in software packages using the finite element method. The prototype antenna module was manufactured using a metallized composite polytetrafluoroethylene material. The network analyzer Ceyear 3272C was used to measure the characteristics of the antenna module prototype.Results. The MIMO module based on two 1/8-mode SAW resonators with notable improvement in both the gain of the radiation elements and their isolation was developed. The results of a study into the relationship between substrate thickness and the features of the module are presented. The possibility of using the developed module in dual-band systems by operating not only on the main, but also on the higher resonant mode of SIW resonators is demonstrated. The design of a MIMO module consisting of eight radiation elements is proposed.Conclusion. The MIMO module design based on two 1/8-mode SIW resonators separated by a gap can be used in dual-band systems operated in several modes. An increase in the substrate thickness was shown to lead to both an improvement in the module’s antenna gain and a reduction in their insulation effectiveness. An antenna module design based on a pair of 1/8-mode SAW resonators, which enables improved insulation between the radiators (up to –30 dB), is proposed.