Introduction. In view of the growing demand for the quality and linearity of RF signal switches, microelectromechanical system (MEMS)-based switches (MEMS-SW) are attracting particular interest. Such devices offer several advantages over other technologies. This article examines the operational and manufacturing specifics of MEMS-SWs, including fabrication and sealing technologies, degradation mechanisms, and design improvements expected to enhance the device performance. Quantitative parameters of commercially available MEMS-SWs are presented. Aim. To review MEMS switch design, production, and factors influencing their mass adoption. Materials and methods. The literature review follows a chronological approach. For evaluating end-component parameters, sources published over the past 10 years were prioritized, while technologies and structural solutions were traced over longer periods to document the evolution of MEMS switches. The final dataset comprised peer-reviewed publications with factual data and official manufacturer specifications. Results. Key characteristics, production and packaging technologies, and required testing methods are described. Materials for MEMS-SW fabrication are analyzed, along with known degradation mechanisms and mitigation strategies. Design solutions for enhancing the performance and parameters of current MEMS-SW are discussed. Conclusion. Although MEMS switch structural components are relatively affordable due to the similarities of fabrication processes with CMOS technology, MEMS-SWs costs remain significantly higher than those of transistor and PIN diode switches, primarily due to packaging and testing expenses. MEMS-SWs outperform electromechanical relays in most applications and are preferable for solid-state switches when linearity and FOM are critical, rather than the size or the switching speed. Continued market growth and performance improvements are anticipated.

Introduction. This paper presents comparative results of electrodynamic modeling and field measurements in an anechoic chamber of a prototype of a printed eight-beam phased antenna array based on the Butler matrix. A mathematical model of a modified differential phase shifter protected by a patent of the Russian Federation and characterized by the highest broadband to date is presented. The topology of an innovative dipole-type radiator with end feeding is proposed and characterized. Aim. To design an eight-beam antenna array based on a systems approach, to model its main electrodynamic characteristics, and to compare them with the results of full-scale experiments. Materials and methods. Electrodynamic models of elements and units of the diagram-forming circuit, as well as the emitter, were designed using the method of induced electromotive forces, mathematical foundations of designing microstrip-technologies, procedures for electrodynamic modeling of elements and units of microwave technology and microwave devices. The FAF-4D domestic dielectric material with a relative permittivity of 2.5 was used. Results. The characteristics of the matching and directivity of the eight-beam antenna array were obtained followed by their comparison with the results of full-wave electrodynamic modeling. As a result, in the frequency band of 2.02…2.37 GHz, an acceptable coincidence of the measured and modeled results is observed for the positions of the beams, cross-polarization intensities, reflection coefficients, and decoupling between the Butler matrix inputs of no worse than 15 dB. Conclusion. The design and final refinement of phased antenna arrays with improved electrodynamic characteristics, taking domestic design and technological standards into account, will form a basis for a qualitative increase in the tactical and technical performance of transceiver devices as a whole, allowing procedures for synthesizing such arrays and their individual units to be developed.

Introduction. Determination of the physical and geometric properties of plasma is a relevant problem in the field of   ion-plasma processes for micro- and nanoelectronics fabrication. The energy of ions and the nature of their interaction with materials define the effectiveness of ion-plasma technologies. The penetration depth and momentum transfer of ions affect the sputtering yield (Y) of the material, which is a key parameter in ion beam technologies. Changes in the ion beam shape have an effect on the ion density distribution. Previous studies have explored the possibility of modifying the design of the ion source to achieve annular or near-Gaussian beam profiles; however, this approach is associated with significant labor and monetary costs. An alternative approach consists in the use of external magnetic systems. Aim. Determination of the physical parameters of a system for ion beam treatment of micro- and nanoelectronic substrates and functional layers. Materials and methods. The research was conducted at the MT-11 Department of Bauman Moscow State Technical University (BMSTU) using the MVTU-11-1MC vacuum system. The material under investigation was silicon and argon ions. Cross-sectional analysis was performed using a CROSSBEAM 550 microscope. The magnetic field strength was determined using a TP2-2U milliteslameter. Results. Calculations and experimental investigations revealed the minimum sputtering yield (Y) to be 0.03 at oms/ion at an energy of 0.05 keV, with the maximum of 1.35 atoms/ion at 7 keV. Subsequently, the sputtering yield decreases to 1.05 atoms/ion at 250 keV due to ion implantation into the lattice structure. The external magnetic system of the source allows the beam cone angle to be modified, which increases the ion concentration at a specific point on the substrate, consequently enhancing the process efficiency. Conclusion. A methodology for calculating the energy of Ar⁺ ions generated by an annular ion source during Si substrate etching has been validated. Processing of the experimental results enabled the determination of the sputtering yield (Y). The derived expression for the magnetic field strength and magnetic field distribution will be used when simulating an additional external magnetic system designed to manipulate the ion beam shape.

Introduction. The rapid development of 5G and Beyond 5G mobile radio technologies does not diminish the importance of research into the accuracy of positioning in widely deployed 4G LTE networks. This paper presents the original results of an integrated study into the accuracy of device positioning in LTE networks under line-of-sight (LOS) conditions. Aim. To substantiate the possibility of achieving an accuracy of user equipment (UE) coordinates of less than one meter with the proper selection of PRS signal parameters and LTE radio access network configuration. Materials and methods. The accuracy limits of primary time-of-arrival (TOA) measurements in a separate radio link between a base station (eNB) and a UE using PRS positioning reference signals were assessed using mathematical modeling and simulation methods, including calculating the Cramer-Rao lower bound for primary TOA measurements. The maximum-likelihood and Fitz-likelihood TOA estimation algorithms were investigated. The accuracy limits of coordinate estimates are demonstrated during secondary processing of primary TOA measurements using the observed time difference of arrival (OTDOA) method. Results. An increase in the PRS signal bandwidth was established to lead to a decrease in the root mean square error   (RMSE) of positioning. When using six resource blocks, positioning accuracy of less than 1 m in a coordinated network is achieved. In uncoordinated networks, the effect of intercell interference significantly degrades accuracy, in the vicinity of base stations in particular, where RMSE can reach 100 m. Conclusion. The study confirms the feasibility of achieving decimeter-level UE positioning accuracy in LTE networks under line-of-sight conditions with the eNB. The results obtained have practical implications for network optimization and can serve as a basis for further research.

Introduction. In order to increase the accuracy of estimating the coordinates of a target, it is necessary to compensate for systematic errors in the nonlinear transformation of coordinates from a spherical system to a Cartesian one. In this paper, we consider the generalization of the well-known coordinate transformation algorithm with compensation for systematic errors when the radar is positioned and oriented arbitrarily in the global Cartesian coordinate system. By applying the proposed algorithm, the coordinate vector and error correlation matrix can be obtained in the global Cartesian coordinate system in the presence of range measurements and angular positions in the local spherical coordinate system associated with the radar position. The proposed algorithm is discussed with respect to trajectory filtering. As a result of the compensation of systematic errors and the calculation of the correlation matrix of the coordinate vector, the accuracy of trajectory tracking is enhanced. Aim. To improve the accuracy of trajectory tracking when using the Kalman filter with converted measurements by means of the mathematical expressions obtained to estimate the coordinates of a target and the error correlation matrix in the global Cartesian coordinate system. Materials and methods. The problem was solved using the methods of mathematical statistics, statistical estimation theory, and computer simulation. Results. Mathematical expressions for calculating coordinates and the corresponding correlation matrix within the global Cartesian coordinate system were derived. Furthermore, comparative graphs illustrating trajectory tracking errors, associated with the use of various methodologies for constructing a Kalman filter based on transformed   measurements, were created. Conclusion. The use of explicit expressions for coordinate transformation, accompanied by compensation for systematic errors, illustrates the potential for a substantial enhancement in accuracy when the errors of primary measurements increase. This improvement can be achieved when applying both direct and straightforward coordinate recalculation methods and a Kalman filter for transformed measurements within the global Cartesian coordinate system.

Introduction. For transportation systems and, in particular, autonomous devices, accurate position determination is an essential requirement. In outdoor environments, the Global Positioning System (GPS) remains the optimal solution due to its broad coverage, high level of automation, and ease of use. However, in indoor environments, the significantly weakened GPS signal creates serious difficulties for accurate localization. For navigation of   transportation devices in confined spaces, the Valve Lighthouse system has been proposed. Although this system exhibits rather low random noise, capable of achieving millimeter-level precision, its accuracy is sensitive to installation-related distortions in the received signal. This leads to errors in position estimation. The current literature lacks methods for identifying these distortions and performing system calibration. To address this gap, this paper proposes an algorithm for estimating the coefficients of a signal error model based exclusively on the coordinates of the transportation device. Aim. Calibration of the signal of an infrared system using exclusively the coordinates of the transportation device in the coordinate system associated with the base station. Materials and methods. An HTC Vive error model of an infrared system was used. The proposed approach is based on Newton’s method and uses a dataset of the true coordinates of the transportation device in the coordinate system associated with the base station, as well as the coordinates determined by the system. Results. The proposed method makes it possible to determine the coefficients of the signal error model of an infrared system using a single base station. Conclusion. A method for calibrating the signal of an infrared system using a single base station is presented. This method is based on Newton’s method and a dataset of transportation device coordinates in the system coordinate frame.

Introduction. In the field of radar monitoring of airspace, multicopter discrimination is a highly relevant task, which includes determination of their class, i.e., small-, medium, or heavy multicopters. The discrimination task is directly related to the analysis of radar signatures and determining the rotor number in a multicopter. Regarding the construction of radar rotors for aircrafts, radar systems obtained using the method of inverse synthetic aperture radar (ISAR) are particularly interesting. In order to create such signatures, information on the rotational frequency of the rotors is required, which can be determined using the method proposed in this paper. Aim. Development of a methodology for estimating the number of rotors in a multicopter based on the analysis of the radar signal of secondary modulation caused by blade rotation. Materials and methods. The task of estimating the number of rotors is related to the task of estimating the frequency of their rotation, which, in turn, is considered as the task of accumulating secondary modulation responses created by rotation in the signal structure with simultaneous compensation of phase incursions. For simulation purposes, a monochromatic signal with a frequency of 10 GHz was considered. Correlation processing and statistical analysis were used to implement and evaluate the algorithms used in the methodology. Results. A methodology for estimating the number of rotors in a multicopter based on the analysis of secondary modulation signals was developed. Its operability was tested by simulating different scenarios of target movement. Conclusion. The developed methodology for estimating the number of rotors in a multicopter based on the analysis of secondary modulation signals forms a basis for developing an algorithm for imaging quadcopter rotors using the ISAR method. Information on the number and rotation frequencies of rotors can be used to construct radar signatures of multicopter rotors based on the ISAR method followed by subsequent evaluation of design features and distinction between single and integrated targets.

Introduction. Due to their high sensitivity to external influences, liquid crystal (LC) cells based on nematic materials, such as 5CB, are widely used in optoelectronic devices. However, the performance characteristics of such cells are significantly affected by operating conditions, including the presence of nanoparticles in their composition. Despite extensive research into the influence of electric fields on LC structures, a comprehensive analysis of switching dynamics under different driving signal shapes in the presence of magnetic nanoparticles such as CoFe₂O₄ remains limited. This study set out to investigate the effect of driving voltage waveform on the dynamic response of an LC composite with magnetic nanoparticles. Aim. To determine an optimal shape of the driving signal that minimizes switching time and ensures stable electro-optical properties of a LC cell with CoFe₂O₄. Materials and methods. The study was carried out on an LC cell containing nematic 5CB with uniformly distributed magnetic CoFe₂O₄ nanoparticles. The cell was driven by sinusoidal, rectangular, and triangular voltage signals generated by a function generator. Measurements were performed using an optical setup including a laser source, crossed polarizers, and a photodiode connected to an oscilloscope. Results. The shortest switching time (4 ms) was achieved with a sinusoidal signal. Rectangular signals produced a 6 ms response, while triangular signals resulted in 5 ms. An increase in the pulse duration led to a greater signal amplitude, having no effect on the switching speed. Conclusion. The study confirmed that the shape of the driving signal significantly affects the behavior of LC cells with CoFe₂O₄. The sinusoidal signal was found to be the most effective in terms of response time, which is important for the development of next-generation high-speed optical devices.

Introduction. In cochlear implant systems, automatic algorithms that include neural response telemetry are not always capable of determining the threshold stimulation current that generates an electrically evoked compound action potential with minimum amplitude on intracochlear electrodes. The target current can be determined by the linear regression method based on the data obtained during telemetry. However, this method does not consider the physiological characteristics of the human auditory system. Aim. Development of a methodology for determining the threshold stimulation current and its implementation in clinical practice, considering the actual physiological nonlinear dependence of the amplitudes of the electrically   evoked potential of the auditory nerve on the stimulation current in cochlear implant users. Materials and methods. Three users of cochlear implant systems were involved. In each of them, it was impossible to conduct neural response telemetry using automated algorithms due to failure of the extracochlear electrode (while maintaining the clinical effect of the implant), lack of a technical сapability to support the automated algorithm (an early model implant), and meningitis with subsequent obliteration of the cochlea. An advanced (compared to the automated algorithm)   telemetry was conducted for each user, performed post-operatively in two users and intraoperatively in one of them. Results. The proposed methodology involves the formation of the growth function of the amplitude of the electrically evoked action potential of the auditory nerve depending on the equivalent stimulation current, finding the first point of the telemetry of the nerve response with a coordinate (equivalent stimulation current, amplitude); finding the zero point corresponding to the maximum value of the current equivalent that does not generate a potential; determining the threshold equivalent current as the average value of the zero and first points. In total, threshold currents on 32 electrodes (for three users) were determined using the proposed methodology and the linear regression method. Conclusion. The methodology can be used in case of failure of the automated algorithm both intra- and postoperatively, thus enhancing the quality of medical care provided to the users of cochlear implant systems.