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Документ Невідомий Automated Precision Amplitudes and Phases Measurement of Polyharmonic Eddy Current Signals of Non-destructive Testing(КПІ ім. Ігоря Сікорського, 2023) Bazhenov, V. G.; Kalenychenko, Yu. O.; Ratsebarskiy, S. S.; Gloinik, K. A.The development of electronic systems like Field-Programmable Gate Array (FPGA) made them available for mass commercial use. This created conditions for the development and application of software and technical tools implemented on FPGA algorithms for fast processing of digital signals. Such solutions, in turn, opened up new opportunities for the spread of multi-frequency eddy current systems (МFЕС) for non-destructive testing (NDT) in the form of systems for simultaneous processing of digital signals of different frequencies, which allows MFEC to effectively compete with pulsed eddy current systems (PEC). This work presents a new algorithm for accurate digital measurement of the MFEC amplitude and phase of harmonic components of polyharmonic signals, which is implemented in hardware and software on FPGA. The measurement of the amplitude and phase of harmonic components is based on the method of orthogonal processing of digital signals, to increase the accuracy of which the necessity of fulfilling the condition of multiplicity of the sampling sequence to the size of the digital signal period has been proved. Compliance with this condition is achieved by adjusting the length of the sampling sequence, which in the proposed algorithm is performed before orthogonal processing. The influence of inaccuracy in setting the length of the sampling sequence on the size of measurement errors when determining the amplitude and phase of the harmonic components of the signal is simulated. As a result of the simulation, it was established that when the multiplicity condition is met, the measurement error significantly decreases, which indicates the high efficiency of our algorithm. The achieved accuracy of measuring the amplitude of harmonic components and the phase of polyharmonic signals due to the given hardware and software implementation of the algorithm makes it possible to create inexpensive, compact, scalable automated digital systems, the measurement data of which can be used both to determine the individual characteristics of the object and to reconstruct three-dimensional images, i.e. in tomographic systems.Документ Невідомий Controlled Brewster effect in the scattering of electromagnetic waves on pseudo-rotating lattices of dielectric resonators(КПІ ім. Ігоря Сікорського, 2023) Trubin, O. O.Various conditions for the occurrence of anomalous scattering, in which most of the power is emitted by the lattice only in the direction of propagation of the incident wave, are analyzed. An analytical model for the scattering of plane electromagnetic waves on arrays of pseudo-rotating dielectric resonators (DRs) of cylindrical and rectangular shape is developed. New analytical relations are derived for the functions that determine the coupling between the field of a plane wave and the main types of magnetic oscillations of the rotated DR. The angles between the axis of the DR and the directions of propagation of plane waves, at which the coupling between the DR and the incident wave reaches extreme values, are studied. The conditions of non-resonant scattering and scattering with the absence of a reflected petal, known as the Brewster effect, were established. The general relations between the angles of inclination of DRs, polarization and the angles of incidence of waves on lattices, which lead to special cases of scattering, were found. There is a similarity between non-resonant scattering and the known Malyuzhynets effect, which describes the passage of waves through lattices of other types. Scattering models for lattices of rotated cylindrical and rectangular DRs were built. The difference between the classical Brewster effect and the petal-free cases of scattering on lattices built on the basis of the use of pseudo-rotating DRs was noted. In particular, it’s shown that, unlike other methods of realizing metasurfaces of this class, cases of scattering without petals on lattices of pseudorotating resonators are possible when the angles of incidence are changed in a wider band. The obtained theoretical results allow us to propose a new class of devices built on the basis of the use of pseudo-rotating DRs, to significantly reduce the calculation time and to optimize complex multi-resonator structures. New types of lattices built on pseudo-rotating DRs can be used to design a wide class of antennas, as well as multiplexing devices in terahertz, infrared, and optical wavelength range communication systems.Документ Невідомий Electromagnetic Compatibility of Implantable Biomaterials for Reconstructive and Restorative Surgery of Facial Bones(КПІ ім. Ігоря Сікорського, 2023) Yanenko, О. P.; Peregudov, S. М.; Shevchenko, К. L.; Malanchuk, V. O.; Shvydchenko, V. S.; Golovchanska, О. D.The critically important part for reconstructive and restorative surgical interventions in facial bones results is the interface of implant-tissue surfaces. The importance of taking into account the processes occurring at the border of the distribution of the implant and living tissue is due to many factors. Among them are well-known ones, such as biological compatibility, consistency of physicochemical parameters, etc. But, at the same time, the issues of electromagnetic interaction between implant materials and biological tissues remain unresolved. So, it’s actual to investigate the interaction of implanted materials and tissues they are in contact. The authors considered the sources of formation of low-intensity microwave signals generated by the implant and living tissue. In this article, the authors demonstrate that microwave electromagnetic radiation is an important indicator and a new criterion for the physical compatibility of dielectric implantation biomaterials. It is proposed to use the term “electromagnetic compatibility” for the possibility of evaluating implant materials. This makes it possible to quantify the materials that come into contact with the human body during implantation. It should be noted that it is extremely difficult to measure the microwave radiation of the implant and biological tissue with existing technical means. This is due to the extremely low power of the emitted signals. The authors created a radiometric system with a sensitivity of 10−14 W. Using a highly sensitive radiometric system, a study of the radiation capacity of a number of implantable biomaterials was conducted. The possibility of forming positive and negative flows of microwave radiation, which can occur between adjacent tissues and implants, is shown. Violations of electromagnetic compatibility and, accordingly, the energy state of the surrounding biotissues, can qualitatively and quantitatively affect the reparative processes in the area of interventions, prolong the recovery period of adjacent tissues. So, it must be taken into account when choosing dielectric implant biomaterials.Документ Невідомий Energy detector of stochastic signals in noise uncertainty(КПІ ім. Ігоря Сікорського, 2023) Buhaiov, M. V.Wide use of software-defined radio has led to a significant sophistication of electronic environment. This is mainly due to ability of generation signals of almost any shape. To detect signals with an unknown dynamic frequency-time structure, it is advisable to use advanced energy detector algorithms. The purpose of this article is to automate processes of stochastic signals detection and time parameters estimation under the conditions of unknown frequency-time structure of signals and noise power. The essence of proposed method is to detect and track temporal energy changes averaged over L samples of received signal in selected frequency channel. Threshold value for a given probability of false alarm is calculated using current estimates of signal power. This threshold is dynamic and is refined only in time intervals free from the signals. In those time windows where energy exceeds threshold, a decision is made about the presence of a signal. An algorithm for detecting stochastic signals is proposed. If a signal is present at the initial moment of time, proposed algorithm can detect only its end by a sharp decrease of signal energy. After that, new noise level is estimated and threshold value is refined. Detection curves of proposed algorithm are obtained. It is shown that when number of samples L is increased by an order, the gain in signal-to-noise ratio in signal detection is about 4 dB. The maximum value of correct detection probability of a pulse signal is achieved with the same pulse duration and the length of the integration interval. Compared to method of signal smoothing with moving average window, proposed method has less computational complexity, simplifies the search for signal time boundaries, and gives smaller errors in signal duration estimates. Recommendations for the implementation of developed algorithm are formulated.Документ Невідомий Error Probability of a Multipath Communication Channel With Inaccurate Estimation of the Impulse Characteristic of Such Channel(КПІ ім. Ігоря Сікорського, 2023) Pochernyaev, V. N.; Syvkova, N. M.; Mahomedova, M. S.The possibility of error in the case of imprecise estimation of the impulse characteristic of a multipath channel is investigated in the article. The study was carried out for a multipath communication channel of discrete channel models, which corresponds to the mapping of a continuous two-path channel onto a discrete channel with an impulse characteristic. Numerical results of calculations are obtained, which can be used to calculate the error probability in the cases indicated in the article, which differ in the ratio of the amplitudes of the interfering beams. Formulas for calculating probability integrals are presented in the article. The influence of the accuracy of estimating the components of the impulse characteristic vector on the error probability in a two-beam channel with constant parameters is studied. The results of a study of the influence of the communication channel model on the error probability for different models of the communication channel for 8PSK modulation are also presented. With the “deterioration” of the type of the channel impulse characteristic (an increase in the number of channel amplitude-frequency characteristic dips in the signal band and an increase in their depth), the decrease in the error probability characteristic due to begins at lower estimation error values. The results of studying the error probability of 8PSK and 64QAM signals in a single-beam channel with Rayleigh fading are presented. It is determined that the influence of errors becomes more noticeable with an increase in the signal-to-noise ratio in the channel and with an increase in the number of dips in the amplitude-frequency characteristic of the channel in the signal band and an increase in their depth.Документ Невідомий Estimation of Multiple Cardiac Cells’ Action Potentials From Extracellular Field Potentials(КПІ ім. Ігоря Сікорського, 2023) Shpotak, M. O.; Ivanushkina, N. H.; Ivanko, K. O.; Prokopenko, Y. V.Modern biomedical technologies use a combination of microelectrode array (MEA) systems and artificially grown cells to study disease mechanisms and test drug effects. MEA systems measure extracellular field potentials (FPs) of cell cultures or tissues, but they cannot record intracellular action potentials (APs) without some modifications or additional devices, limiting the depth of electrophysiological analysis. One of the possible solutions to the inability of MEA systems to measure APs is to mathematically reconstruct them using recorded FPs. However, accurately reconstructing APs of multiple cells is challenging task, which is complicated by many factors such as the number of cells, synchronicity of their APs, identification of their electrophysiological parameters, and noise. This paper aims to address the mathematical problem of AP synchronicity, asynchronicity and partial synchronicity between multiple cells. In this study, mathematical techniques were employed to derive a system of equations capable of reconstructing the APs of N cells simultaneously, using the FPs recorded with N + 1 electrodes. The equations take into account the number of cells, synchronicity and variation of their APs and specific electrical properties of the cells and the medium. In numerical experiments the equations were applied to reconstruct APs from FPs for cases with different types of synchronicity in noise-free and noisy conditions. The reconstructed APs, when combined with recorded FPs, expand the number of electrophysiological characteristics available for cardiotoxicity assessment in MEA systems.Документ Невідомий Improvement of Mathematical Models with Time-Shift of Two- and Tri-Fragment Signals with Non-Linear Frequency Modulation(КПІ ім. Ігоря Сікорського, 2023) Kostyria, O. O.; Hryzo, A. A.; Dodukh, O. M.; Nariezhnii, O. P.The use of signals with intra-pulse modulation in radar systems allows us to increase the duration of sounding pulses, and therefore the radiated energy with limitations on peak power. In the processing system, compression of the signal provides the necessary time difference, but leads to the appearance of side lobes. This, in turn, causes the “stretching” of the passive interference zone by range and worsens the potential for target detection. Therefore, reducing the level of the side lobes of the processed signal is an urgent task of radar. With regard to the maximum level of side lobes, signals with non-linear frequency modulation have advantages, but the models used for their mathematical description need to be clarified. The research carried out by the authors of the article and the obtained results of mathematical modelling explain the mechanism of frequency and phase jumps in signals with nonlinear frequency modulation, consisting of several linearly frequency modulated fragments. These results are obtained for the mathematical model of the current time, when the time of each subsequent fragment is counted from the end of the previous one. The article discusses mathematical models of two- and three-fragment signals with using different approach. The difference is that the start time of each successive linearly frequency modulated fragment is shifted to the origin, that is, the shifted time is used. The advantage of this approach is the absence of frequency jumps at the joints of fragments, but phase jumps at these moments of time still occur. Thus, there is a need to develop a mathematical apparatus for compensating of such jumps. An analysis of known publications conducted in the first section of the article shows that for mathematical models of shifted time, the issue of determining the magnitude of phase jumps at the joints of fragments and the mechanisms for their compensation were not considered. From this follows the task of research, which is formulated in the second section of the work. Mathematical calculations for determining the magnitude of phase jumps that occur in these mathematical models, as well as the results of checking the improved mathematical apparatus, are given in the third section of the work. Further research is planned to be directed at the features of using the developed mathematical models in solving applied problems in radar systems.Документ Відкритий доступ Investigation of fundus images for detection of diabetic retinopathy stage using deep learning(КПІ ім. Ігоря Сікорського, 2023) Basarab, M. R.; Ivanko, K. O.The study is dedicated to the investigation of diabetic retinopathy images by digital processing methods and further pathological outcome levels classification. The application of image processing methods to the problem of diabetic retinopathy (DR) analysis is considered in the paper. In order to investigate the possibilities of machine learning for the problem of classification of retinal images, the dataset of retinal images, which represent 5 classes: absence of DR, moderate, mild, proliferate stages, and severe DR, was used in this work. The aim of this study is to identify and compare the different image processing methods used for diabetic retinopathy detection, as well as to choose the classification method that provides the highest accuracy in the identification of the human retina condition. The convolutional neural networks with tuned parameters such as EfficientNet and ResNet were applied to determine the best classification models for computerized disease screening. The accuracy and losses of the different models were determined and compared. Based on this, a combination of image preprocessing steps and neural network models, which provide the highest accuracy of diabetic retinopathy condition recognition, reaching 91.4% for the task of recognition of 5 classes (absence of DR and 4 stages of DR) is proposed. Intermediate stages in the development of diabetic retinopathy are the most difficult to distinguish: the best model showed 85.2% of correctly defined cases of moderate stage of diabetic retinopathy and 83% of correctly defined cases of mild stage. Overall, this article highlights the significance of artificial intelligence (AI) and deep learning in the detection and classification of diabetic retinopathy. It underscores the need for improved screening methods, especially in underserved areas, and emphasizes the potential of these technologies in preserving vision, reducing healthcare professionals’ workload, and promoting widespread adoption in clinical practice. The article also acknowledges the challenges associated with image variability and the potential impact on AI model performance, calling for further research and improvement in image quality and consistency.Документ Відкритий доступ Issues of Optimizing Detection of Stealth Aircraft Using Group of Satellites Flying at Different Altitudes(КПІ ім. Ігоря Сікорського, 2023) Agayev, F. G.; Asadov, H. H.; Aliyeva, G. V.The article is devoted to the optimization of the detection of stealth aircraft using a group of satellites flying at different altitudes and equipped with an infrared reproducing system. The main sources for the formation of the infrared signature of stealth aircraft are the heating of the aircraft casing during flight and the high-temperature plume emanating from the nozzle of the aircraft engine. The necessity of calculating the infrared signature of stealth aircraft is noted. The infrared signature of such aircraft is usually calculated in wide ranges of IR waves. At the same time, there are works according to which it is advisable to use narrow spectral wavelengths for these purposes. A push-pull method of detecting stealth aircraft using satellites flying in a group at different orbital altitudes has been developed. The proposed method makes it possible to increase the signal-to-noise ratio in the resulting informative signal, which is the difference between the signal from the aircraft itself and the background signal within the frame. It is shown that the introduction of a binary control signal depending on the spatial resolution of the distance to the satellites allows minimizing the total background signal coming from a group of satellites. At the same time, an increasing version of this function applied to the sum of signals from the background under a given restrictive condition ultimately increases the signal-to-noise ratio in the system, and also increases the probability of detecting a stealth aircraft using spectrometric devices installed on satellites.Документ Відкритий доступ Mathematical Model of Two-Fragment Signal with Non-Linear Frequency Modulation in Current Period of Time(КПІ ім. Ігоря Сікорського, 2023) Kostyria, O. O.; Hryzo, A. A.; Dodukh, O. M.; Nariezhnii, O. P.Advantages of using frequency-modulated signals for locating objects are the possibility of using long-term probing pulses. Such signals provide the required radiated power while maintaining the desired discriminating power from range. One such signal that has found wide application is a signal with linear frequency modulation. An undesirable effect of the matched filtering of such a radio pulse is a sufficiently large level of side lobes of the compressed signal at the output of the processing device, the maximum level of which is approximately minus 13 dB. Such an effect may lead to an increase in the probability of false detection or masking of less powerful signals by side lobes of signals with greater power. One method of reducing the level of side lobes is the use of signals with non-linear frequency modulation. An example of such signals is a known two-fragment signal consisting of linearly-frequency modulated fragments in time. However, the mathematical models used to describe such a signal do not fully reflect the effects that occur at the moment of transition from one fragment of the signal to the second. These effects are manifested in a sudden change in frequency and phase, which leads to distortion of the signal spectrum, an increase in the level of the side lobes of the autocorrelation function and sharp changes in their level. Such effects have not been studied in known works, as evidenced by the results of the analysis of studies and publications given in the first section of the article. In the second section of the work, the research task is formulated. The third section of the work is devoted to the development of a mechanism for compensating for the manifestation of detected effects and its mathematical description, which is verified by modeling. Taking into account the detected effects, a new mathematical model of a non-linear frequency modulated signal has been developed. In contrast to those known in the proposed model, instantaneous frequency and phase jumps are compensated for, which occur at the moments when the frequency modulation rate changes during the transition from one signal fragment to another. Further studies should be focused on the peculiarities of compensation for the manifestation of detected effects for signals with a large number of fragments, as well as combinations of fragments with different types of modulation, as indicated in the conclusions on the work.Документ Відкритий доступ Mathematical Modeling of Piezoelectric Ceramic Ring Transducers for Functional Instrumentation(КПІ ім. Ігоря Сікорського, 2023) Bazilo, C. V.; Anriienko, V. O.; Tuz, V. V.; Usyk, L. M.; Bondarenko, Yu. Yu.The article reviews a mathematical model of piezoelectric ceramic ring transducers which are functional, highly effective, and applicable as components of functional instrumentation devices, such as sensors, automatic control devices, measuring devices, data collection devices, electronic control systems, etc. The main distinctive characteristic of the mathematical model developed in this study is the ability to establish analytical dependencies for determining such electromechanical characteristics of a piezoceramic ring as: electrical impedance, quality factor, elastic modulus, piezo modulus, dielectric constant, as well as the amplitude values of the electric charge and electric current on the electroded surfaces of the piezoceramic ring, thus significantly expanding the range of these products and determine their operational characteristics at the design stage. The key research question of this study is frequency dependence of the change in electrical impedance for a ring made of PZT-type (plumbum zirconate titanate) piezoelectric ceramics, which significantly depends on the values of mechanical and geometric parameters, the wave number of elastic oscillations, as well as the corresponding Bessel and Neumann functions of the first order, according to which a sharp decrease in the electrical impedance from 4900 to 10 Ohms is observed when the quasiwave number increases from 0 to 2. Also, this study has established a high degree of convergence between the theoretically obtained and experimentally determined electrical impedance modules for ring transducers made of PZT-type piezoelectric ceramics (the discrepancy between the impedance values in these cases did not exceed 16%).Документ Відкритий доступ Mathematical modeling the electrical impedance of the piezoceramic disk oscillating in a wide frequency range (Part 1. Low frequencies)(КПІ ім. Ігоря Сікорського, 2023) Bazilo, C. V.; Trembovetska, R. V.; Usyk, L. M.; Faure, E. V.; Chorniy, A. M.The article presents the results of mathematical modeling and analysis of the electrical impedance of a piezoceramic disk that undergoes oscillations at low frequencies, i.e., when the length of the elastic wave significantly (by an order of magnitude or more) exceeds the radial size of the disk. Thus, the proposed mathematical model of disk-shaped ceramic elements of piezoelectric transducers, which are an important component of modern communication devices, environmental sensors, precision equipment, medical devices, etc. A key characteristic of the mathematical model described in the article is its ability to determine analytical dependencies that allow estimating such fundamental electrical properties of the piezoceramic disk element as electrical impedance and quasi-static electrical capacitance, thereby significantly simplifying the calculation of such an element already at the design stage. The static dielectric permittivity of a piezoceramic disk vibrating at low frequencies has been investigated. The calculated value of this parameter, based on the physical constants’ characteristic of the piezoceramic of the PZT (lead zirconate titanate) type, is 1.844 times higher compared to the high-frequency (dynamic) dielectric permittivity. It has been found that in the low-frequency range, when the mechanical stresses in the vibrating piezoceramic disk approach zero and the direct piezoelectric effect is almost negligible, the electrical impedance of such a disk can be described as the reactive resistance of a capacitor with electrical capacitance equivalent to the quasi-stationary capacitance of the disk. This is confirmed by a high degree of convergence between theoretical data and experimental results, with discrepancies not exceeding 6%. The results obtained in the article can be valuable for scientific research in the fields of precision instrument engineering and radio equipment manufacturing. Additionally, they have practical applications in the development and production of high-tech equipment.Документ Відкритий доступ Mathematical Modelling of Disk Piezoelectric Transducers for Acoustoelectronic Devices(КПІ ім. Ігоря Сікорського, 2023) Bazilo, C. V.; Bondarenko, M. O.; Usyk, L. M.; Faure, E. V.; Kovalenko, Yu. I.This study has presented an algorithm for assembling, solving, and analyzing the results obtained by mathematical modeling of the disc piezoelectric transducers, which are widely used in hydroacoustics, microelectronics, microcircuit engineering (for example, as components of receiving antennas of hydroacoustic communication devices). The models developed in this study enable us to establish dependencies, which represent a mathematical description of the electroacoustic connection between the wave fields in different sections of the disc piezoelectric transducers. Analytical dependences obtained by mathematical modelling make it possible to establish the electrical impedance and quality factor together with the amplitude values of the electric charge and current on the electroded surfaces of the piezoelectric disk, subject to the inverse piezoelectric effect conditions. A complete calculation of the problem of harmonic radial oscillations of disc piezoelectric transducers allowed the authors to significantly expand the list of physical and mechanical parameters of the piezoelectric material, which had been previously determined experimentally. The research has revealed the dependence of the change in electrical impedance on the values of the electromechanical coupling coefficient, the wave number of elastic oscillations, and the Voigt indices. The study has also determined a high agreement between the electric impedance modules of discs made of lead zirconate titanate PZT piezoelectric ceramics with and without the piezoelectric effect (the difference between the impedance values in these cases did not exceed 18%).Документ Відкритий доступ Method of Complex Envelope Processing for Signal Edges Detection(КПІ ім. Ігоря Сікорського, 2023) Buhaiov, M. V.Problem statement. The need of information processing automation in modern radio monitoring systems stimulates development of flexible methods for signal detection and its parameters estimation in time domain. A priori uncertainty of signal time-frequency structure complicates the automatic determination of signals edges. Purpose. The purpose of the article is subsequent automation of radio frequency spectrum analysis process by developing and implementing a method for determining signals time edges under conditions of a known noise power and signal-to-noise ratio. Method. To determine signal time edges in given frequency channel, square of signals’ complex envelope is first calculated, smoothed with moving average window and compared with threshold. Threshold is calculated as a quantile of gamma distribution using Wilson-Hilferty approximation of х 2 distribution quantiles for a given probability of false alarm. An analytical expression is obtained for calculation length of moving average window depending on signal-to-noise ratio. An algorithm has been developed for determining signals’ time parameters and filtering them by duration. Unknown noise power value in frequency channel can be replaced by its estimate under the assumption that frequency channel is not constantly occupied and noise level is estimated on signal-free time intervals. Conclusions. Proposed method makes it possible to automatically determine edges of signal with an arbitrary structure at signal-to-noise ratio values from -6 dB. Adjustable length of moving average window makes it possible to reduce the error in determining signal time parameters by 2-4 times with an increase in the signal-to-noise ratio compared to a fixed window length. Prospects for further research in this direction should be focused on development and implementation of methods for detection signal edges under conditions of an unknown noise level.Документ Відкритий доступ Pадiацiйна стiйкiсть тестових npn транзисторiв IC з дiелектричною iзоляцiєю, виготовлених на кремнiї, iзовалентно легованому германiєм (SiGe)(КПІ ім. Ігоря Сікорського, 2023) Биткiн, С. В.; Критська, Т. В.Cклалася суперечлива оцiнка можливостi застосування германiя (Ge) для пiдвищення радiацiйної стiйкостi однорiдно легованого iзовалентною домiшкою кремнiю (Si). У рядi публiкацiй показано, що iснує лише обмежений вплив легування германiєм на радiацiйну стiйкiсть pn-структури при високоенергетичному електронному опромiненнi. Одночасно, спостерiгається помiтне покращення радiацiйної стiйкостi npnp-структур, виготовлених на SiGe, при γ-опромiненнi. З метою зняття протирiччя, проведене порiвняння радiацiйної деградацiї β тестових бiполярних транзисторних npn-структур iнтегральних схем (IС), виготовлених за однаковою технологiєю, «кремнiй з дiелектричною iзоляцiєю», на iзовалентно легованому германiєм кремнiї, SiGe, з рiзним вмiстом Ge, NGe =1,2·1019 ...1,2·1020 см−3. Коефiцiєнт статичного посилення β вимiряний до та пiсля опромiнення α-частинками. Опромiнення не корпусованих npn-структур α-частинками з енергiєю 4,5МеВ, проведене у спецiально спроектованiй та виготовленiй лабораторнiй установцi з використанням радiоiзотопних джерел; експериментально дослiджено npn-структури з двома товщинами бази, 0,25 i 0,35мкм. Залежнiсть, що апроксимує експериментальнi данi β(Φα) – рiвняння, що описує змiну коефiцiєнта посилення транзисторної npn-структури при α-опромiненнi, отримана з використанням програми OriginPRO. Результати для npn-структур с товщиною бази 0,25мкм показують сильну нелiнiйну залежнiсть рiвнянь β(Φα) вiд NGe. Деградацiя коефiцiєнта посилення контрольних транзисторiв, виготовлених за стандартною технологiєю (NGe =0), описується S-образною залежнiстю. Опромiнення npn-структур, сформованих на пластинах SiGe з рiзним рiвнем легування iзовалентною домiшкою призводить до повної змiни характеру залежностi. Для Φα ≤ 1011 см−2 характер змiни β практично однаковий для структур, виготовлених на пластинах з NGe =0 та NGe =2,5·1019 см−3, а також NGe =1,2·1019 см−3 та NGe =1,2·1020 см−3. При збiльшеннi Φα ≥ 1011 см−2 спостерiгається прискорена деградацiя коефiцiєнта посилення npnструктур, виготовлених на пластинах NGe =2,5 · 1019 см−3. Цей рiвень легування кремнiю германiєм не прийнятний з погляду пiдвищення радiацiйної стiйкостi Si. При Φα ≤ 1014 см−2 радiацiйна стiйкiсть npn-структур, виготовлених на пластинах SiGe з NGe = 1,2 · 1019 см−3 приблизно в два рази нижче, нiж у контрольних структур з NGe =0. Для транзисторiв з товщиною бази 0,35мкм вiдсутнiй ефект змiни характеру деградацiї β(Φα). Спостерiгається залежнiсть, шо пiдтверджує можливiсть уповiльнення радiацiйної деградацiї значення коефiцiєнта пiдсилення npn-структур, виготовлених на SiGe. Пiдвищення радiацiйної стiйкостi в 2...3 рази для тестових транзисторiв, виготовлених на пластинах SiGe, легованих NGe = 7,5 · 1019 см−3, спостерiгається в широкому дiапазонi доз α-опромiнення, 1011 ≤ Φα ≤ 1014 см−2.Документ Відкритий доступ Rationale for Choosing Type of Heatsink Profile for New Design of Electronic Module Cooling System(КПІ ім. Ігоря Сікорського, 2023) Nikolaenko, Yu. E.; Pekur, D. V.; Nikolaienko, T. Yu.; Kravets, V. Yu.The reliable operation of complex electronic systems with increased heat generation is ensured by the use of efficient cooling systems, the cost of which is sometimes up to 45% of the cost of electronic modules that are cooled. In this regard, the development of new design solutions aimed at reducing the cost of electronic module cooling systems is an urgent task. In this work, a new design solution to reduce the cost of the basic version of the air cooling system of the transmit/receive (T/R) module is proposed. Instead of the heatsink case of the T/R module made by the method of milling from a solid aluminum plate 53 mm thick, a design is proposed, which consists of two parts: an improved case part, made by the method of milling from an aluminium plate with half the thickness, and a convective heat exchanger attached to it, made from a serial heatsink profile. Active electronic components are in contact with the surface of the heat exchanger through the windows in the case. The main part of this work is devoted to rationale for choosing the most advantageous from a thermal point of view heat sink profile from the existing serial profiles for use in the new cooling system. Using computer simulation, the thermal performance of the proposed cooling system was determined and compared in two versions: based on a serial heatsink profile of type 1 and based on a serial heatsink profile of type 2. Types 1 and 2 of the heatsink profile are similar, but have different geometric characteristics, different number of fins, different fin heights, different base thicknesses and different weights. The purpose of the simulation is to determine the most effective of them for use in the new T/R module cooling system. As a result of simulation, it is shown that the most effective for use in the design of the T/R module air cooling system is a serial type 1 heatsink profile, made of aluminum-magnesium alloy AD 31Т. It has a base thickness of 4 mm, a fin height of 21 mm, a fin pitch of 7 mm, a fin thickness at the base of 2.5 mm, and a fin thickness at the top of 1 mm.Документ Відкритий доступ Scattering of Plane Electromagnetic Waves by Lattices of Spherical Dielectric Resonators with Degenerate Lower Types of Natural Oscillations(КПІ ім. Ігоря Сікорського, 2023) Trubin, A. A.The problem of scattering of plane electromagnetic waves on lattices of spherical dielectric resonators (DRs) with low magnetic oscillations is considered. The results of theoretical calculations of complex coefficients of mutual coupling of spherical dielectric resonators in open space for cases of excitation of degenerate types of oscillations are presented. The expressions found coincide with those obtained earlier for the special case of oscillations of resonators excited along or perpendicular to the line connecting their centers. The main regularities of the change in the coupling coefficients with variations in the coordinates of the resonators in the transverse plane are considered. Analytical expressions for c-functions are found for the field of fundamental magnetic oscillations of a resonator and a plane wave in open space. On the basis of the obtained formulas, with the help of the perturbation theory, the characteristics of the scattering of plane waves on a square lattice of spherical DRs with basic degenerate magnetic oscillation types are calculated and studied. The distribution of the scattering field in the wave zone of the grating is studied for different angles of incidence. The regions of variation of the angles of incidence are determined, in which the scattering amplitude of a lattice constructed on the basis of spherical DRs differs most noticeably from DR lattices of other shapes with nondegenerate types of oscillations. The polarization characteristics of scattered waves in the far zone of the lattice are calculated. It is noted that, in contrast to the lattices of pseudorotating cylindrical DRs with the main magnetic types of oscillations, lattices based on spherical resonators are characterized by a more complex distribution of the polarization of scattered waves. In the wave zone of the lattice, scattered waves of all three types of polarization, linear, circular, elliptical, can be observed. The obtained results significantly expand the possibilities of developers, since allow us to create electrodynamic models of lattices, as well as other devices in the millimeter and infrared ranges, built on the basis of the use of spherical resonators with oscillations of the main types. Such lattices can be used in antennas, passive reflectors, and other devices of modern optical communication systems.Документ Відкритий доступ Second-Order Filters with Independent Setting and Adjustment of Basic Parameters(КПІ ім. Ігоря Сікорського, 2023) Antypenko, R. V.; Kyrpatenko, I. M.; Movchanyuk, A. V.; Fesich, W. P.A new topology of the second-order low-pass filter containing three operational amplifiers is proposed. As known, a feature of second-order filters based on operational amplifiers is the interdependence of the main filter parameters, such as the pole frequency, Q factor and gain. The second-order filters synthesized by the state variable method have the smallest relationship between the main parameters, but they also do not allow independent adjustment of the gain and Q factor, and contain at least three operational amplifiers. The proposed low-pass filter topology also contains three operational amplifiers and provides the possibility of independent setting of the pole frequency, Q factor and gain, as well as the possibility of independently adjustment of the Q factor and gain. Relationships have been obtained that relate the pole frequency, Q factor and filter gain to the nominal values of the passive filter elements. On the basis of these ratios, the possibility of independently changing the Q factor and gain of the filter is shown. On the basis of this topology, a second-order universal filter was synthesized with the possibility of independent setting and adjustment of the main parameters. A cut-off filter with independent installation and adjustment of the main parameters is also offered. Examples of second-order low-pass filter calculations and simulation results are given, which confirm the correctness of the calculations. Also, the results of modeling universal and rejection filters are given.Документ Відкритий доступ Towards a New Implementation of Bandpass Filters on Basis of Band-Stop Structures on Dielectric WGM Microresonators(КПІ ім. Ігоря Сікорського, 2023) Grygorenko, O. G.; Trubin, O. O.A new method of constructing band-stop filters based on a system of optical microresonators with whispering gallery oscillations of ultra-high Quality factor (Q) is proposed, which are widely used in various integral filters of the optical wavelength range. To reduce the mutual coupling, the system of microresonators is located on different sides of the regular transmission line. With the help of perturbation theory, an electrodynamic model of filters was developed, which describes a complex system of interconnected microresonators with doubly degenerate types of natural oscillations. The obtained general analytical expressions are used to describe the characteristics of the scattering of natural waves of the line on the system of optical microresonators, which form a band-stop filter or an alternative band-pass filter. The frequency dependencies of the filter scattering matrix were calculated and analyzed. On the basis of the built analytical model, and using the periodicity of the microresonators’ own oscillations, with a change in the free spectral range (FSR) value, the possibility of constructing a new class of band-pass filters has been proven. The new filters differ from the known ones in that they simultaneously use two types of natural oscillations of adjacent microresonators. Amplitude-frequency characteristics of filters with different sizes of operating frequency bands are calculated. Based on the comparison of the obtained data, a conclusion about the reduced dependence of the losses of the proposed filters on the bandwidth is made. It is noted that the amplitude-frequency characteristics of the new class of filters are close to linear ones. The obtained practical simulation results allow significantly reducing the calculation time and optimizing complex multi-resonator structures for optical communication systems.Документ Відкритий доступ Transverse Resonance Technique for Analysis of Symmetrical Stub in Microstrip Transmission Line(КПІ ім. Ігоря Сікорського, 2023) Rassokhina, Yu. V.; Krizhanovski, V. G.Open or short-circuit stubs in a strip (microstrip) transmission line are one of the most common elements of planar circuits used in numerous devices in the microwave frequency range: various types of filters, couplers, power amplifiers, antennas, sensors, wireless energy transfer systems, etc. Modern planar circuits in the microwave frequency range already contain stubs of a complex shape and a complex pattern inside the microstrip line. Therefore, an urgent problem is to develop an analyzing method for discontinuities in form of the closed or open stub in a microstrip transmission line at frequencies at which the transmission line theory already has significant errors and high-frequency effects must be considered. In paper a technique of scattering characteristics calculating on a symmetrical microstrip open stub by transverse resonance method is presented. Boundary value problems for a rectangular volume resonator based on a microstrip transmission line with a symmetric open stub are solved for three different boundary conditions in the plane of symmetry and on the longitudinal boundaries. To algebraize the boundary value problems for the resonator’s eigen frequencies with discontinuity, the corresponding two-dimensional functions of the magnetic potential are constructed, through which the components of the current density on the strip are calculated. The magnetic potential functions were written by decomposing them into series by orthogonal Chebyshev polynomials, which consider the behavior of the field on a thin edge and ensure fast convergence of the series and the algorithm. The developed algorithms were tested by calculating the scattering characteristics of a microstrip open stub using the transverse resonance method on the example of open stub in a microstrip transmission line with a resonant frequency of about 3.0 GHz. In addition, the method was tested on the example of numerical calculations of the dependence of resonant reflection frequencies of an open stub on its width.