Wearable antennas for body-centric wireless communications have become very popular recently. Wearable antennas are body worn as a part of clothing on the human body and enable hands-free operation, which should also be comfortable. The latest 5G wireless technology has many advantages over 4G like high data transmission rate, low latency, etc. With the help of advanced and innovative technologies, wearable antennas can be developed using various materials. This paper presents a detailed review of the application of wearable antennas designed specifically for 5G and body-centric wireless communications. It also presents the selection of materials for the antennas and different fabrication techniques. The paper also looks at the bending of antennas at different radii and analyzes its impact on durability.

Photonic integrated circuits constitute a vital component of contemporary telecommunications systems, facilitating traffic management and reducing energy consumption. However, the integration of these components presents a significant challenge in the form of high polarization sensitivity, which has the potential to limit the overall performance of the device. The objective of this study was to develop a design method and fabrication technology for polarization converters based on silicon nitride-on-insulator. The design of the polarization converters was optimised through the utilisation of finite element method simulations, conducted using the ANSYS Lumerical software. The device features an asymmetric rib waveguide, which facilitates efficient polarisation rotation. The technological implementation comprised plasma chemical vapor deposition of silicon nitride films, three-dimensional laser lithography, and reactive ion etching. A technological assessment determined that the reproducibility tolerance was ± 60 nm. To address this limitation, a mirrored section was incorporated into the polarization converter design, thereby increasing the allowable fabrication tolerance to ± 215 nm without compromising device performance. The optimised polarization converter exhibited a high level of polarization rotation efficiency, reaching 96.3 %, and an output power of 98.32 %. The utilisation of an asymmetric rib waveguide was pivotal in attaining these outcomes, facilitating the transfer of optical power from fundamental transverse electric to fundamental transverse magnetic modes. The incorporation of a mirrored section enhanced the device's manufacturability, maintaining performance despite geometric deviations. These findings highlight the robustness of the proposed design under typical fabrication constraints. This study presents a novel design and fabrication method for silicon nitride on insulator-based polarization converters. The proposed approach improves efficiency and stability. These results provide a foundation for future advancements in integrated photonics, with potential applications in telecommunications and beyond.

Development of rifle electronic simulators (i. e. for hand weapons and not using ammunition) is an important task since the production of any type of small arms, according to regulatory documents, requires also production of a simulator to instill aiming and firing skills. The developing family of electronic shooting simulators "STrIzh" includes three publicly available levels for self assembly: initial, basic and virtual. Structural diagrams of aiming point’s recorders of initial and basic levels are presented and studies of their mathematical models with estimation of errors are carried out. Ability to self assemble a shooting simulator from publicly available components (laptop, webcam, weapon layouts, IR LEDs, projector, lasers, HD-camera) contributes to their widespread use. Such use is based on the program exercise support under development and methods of assembling and adjusting the targeting point recorders and weapon simulators. Studies of recorders for the error in determining of the aiming point showed acceptable accuracy and manufacturability of mathematical models’ calibration with the ability to take this error into account in the simulated ballistic dispersion of ammunition. Possibility of registration speed increasing and possible approaches for increasing of the accuracy and fixation of the pile and the distance to the workplace with the possibility of recalculating the angular dimensions of the target situation to the real one were investigated also. The simulator family’s software algorithm should fully support the initial and basic levels of implementation with various training equipment configurations and include a multimedia shooting training system. For the virtual level of the simulator (a virtual reality helmet on a smartphone and a weapon’s layout with a smartphone), one needs to develop his own software (it will be discussed in the next articles).

Diagnostic methods that will change at present for monitoring the condition of windings of electric machines do not allow to detect defect formation in them at early stages of development. And this problem is especially relevant for equipment that is directly in its operating mode. The purpose of the work was to consider and evaluate the possibility of a method that, based on the analysis of the parameters and characteristics of the no-load current, will allow to characterize the state of the current-carrying parts of the windings of diagnosed electric machines. The paper presents the results of experimental studies of the patterns of influence of the level of defective resistance of interturn insulation in the windings of electric machines on the parameters of the no-load current, including the features of changes in the parameters of its spectral components. The article also defines analytical dependencies of the obtained characteristics of influence and analyzes the factors that determine the measurement errors of the developed method. The presented method based on the analysis of the parameters of the spectral components of the no-load current is intended for measuring the resistance of the interturn insulation of current-carrying parts in the windings of electrical machines under their operating conditions, with the possibility of recording the onset of defect formation, which will allow real-time assessment of its operational, pre-failure and serviceable state.

The aim of the work was to study the structure and defects of a channel transistor with two types of conductivity (p and n), the submicrostructures based on nickel silicide films, and the seed layers based on AlN using atomic force microscopy (including conductive or electric force method, which allow one to study the electrical conductivity of the material surface). The influence of the manufacturing technology and local oxide formation on the relief and structure of the pand n-type transistor was established. The local oxide is necessary for the electrical isolation of the transistors from each other. The surface roughness is higher on the surface and outside the p-channel transistor than on the n-channel transistor. When examining the AlN layers both in the topography mode and in the adhesion mode, defects in the form of pores were revealed, which are places of electrical breakdowns, which worsens the properties of the such heterostructures. With an increase in the temperature and time of nitriding, the defects of the AlN layers significantly decrease. The conductive areas on the surface of the nickel silicides after rapid thermal treatment at 300 and 400 °C using electric force microscopy were detected, which shows incomplete formation of nickel silicide during the treatment. Thus, the efficiency of the atomic force microscopy method using a specialized conductive technique as a method for monitoring microelectronic components was demonstrated.

Modern microelectromechanical systems (MEMS) are devices that incorporate microelectronic components and micromechanical structures on a single chip. Packaging is a mandatory stage in MEMS manufacturing. It ensures mechanical protection, sealing and transmission of electric energy and signals. The present work was aimed at developing a MEMS packaging method as a part of the consolidated manufacturing process. The method is developed on the example of a microwave MEMS switch. The switch manufacturing scheme includes conventional technologies used for producing gallium arsenide integrated circuits: optical lithography, liquid etching, electron-beam and magnetron deposition of metallic, resistive and dielectric films. The work presents a new inter-plate MEMS packaging based on a frame structure with a passivating film. The main purpose of the package frame layer is mechanical support for an upper layer of the sealing material. The frame layer should have the structure allowing for unimpeded removal of the sacrificial photoresist and be impermeable for the sealant. To satisfy the requirements stated, a metallic thin copper-film spatial frame was fabricated by galvanic deposition. The frame structure is a geodesic dome comprised of a complex network of triangle cells arranged in rows. The connected triangles create a self-supporting durable framework. The measurement and modeling results demonstrate that the round frame structure is more durable than a square frame with the same maximum cell dimensions. The stress-strain state for the round framework considerably alters depending on the number of rows of triangle cells. In addition to the mechanical support, the cell structure of the framework – with adequate selection of cell dimensions, solvent and sealant viscosities – allows for unimpeded penetration of the solvent (N-methyl-2-pyrrolidone, NMP) and removal of ma-P1225 photoresist sacrificial layers. At the same time, the layer structure is impermeable for the sealant (benzocyclobutene, BCB). The proposed MEMS switch packaging enables mass fabrication of GaAs integrated circuits in a single process, which expands their frequency range. The new plate-level packaging technology is absolutely compatible with MEMS fabrication technology without specific materials and equipment which reduces the dimensions and cost of MEMS.

When assessing the quality of products, especially oil and oil products, the density value is widely used along with other parameters. Density data are fundamental for studying the properties of liquids, their identification and determining the degree of purity. They are also necessary for indirectly assessing with a certain degree of accuracy some other properties of the liquid, such as specific gravity, thermal expansion or contraction, the mass of a known volume of liquid, etc. In turn, the accuracy of the density determination determines the correctness of the decision made in the technological quality control of the manufactured products. Determining the density of a liquid with high accuracy requires maintaining stable temperature conditions during the measurement process. The purpose of the work was to establish the effect of temperature stability on the reproduction and transmission of the unit of liquid density. To stabilize the temperature, a technical solution is proposed, implemented in the form of a climatic chamber, inside which reference equipment is placed. A study of the temperature conditions in the process chamber was carried out. It was found that due to the technical solutions used, the influence of environmental conditions on the change in the temperature of the liquid under study is a negligible value.