Background. Queueing systems are in demand for mathematical modeling of data transmission systems and networks. The distribution laws that shape the queueing system play a key role in this process. As is known, the laws of distribution in the form of probability mixtures provide a wide range of changes in the coefficients of variation of time intervals, which have a major influence on the value of the average waiting time of requests in the queue. Aim. In this work, the hyper-Erlangian and hyper-exponential distributions of the second order were chosen as the distribution laws that form the queueing system. For them, numerical-analytical models were constructed for two queuing systems with usual and shifted distribution laws, with the derivation of a solution for the main characteristic of the queuing system – the average waiting time in the queue. As is known from probability theory, a shift of the distribution law to the right from the zero-point leads to a decrease in the coefficient of variation. Methods. The work uses the method of spectral solution of the Lindley integral equation based on the Laplace transform of the distribution laws that form the considered queueing system, as well as the shift of these distribution laws to the right. The methods used make it possible to obtain numerical-analytical models for the average waiting time in a queue and to calculate the characteristics of such systems for a wide range of changes in teletraffic parameters. Results. Calculation formulas for the average waiting time in a queue for the above-mentioned systems in closed form are obtained. The remaining characteristics are derived from the average waiting time. The obtained results can be used in modern teletraffic theory when designing and modeling various promising data transmission systems. Conclusion. A shift of the distribution laws to the right from the zero-point leads to a decrease in their coefficients of variation. Considering the quadratic dependence of the average waiting time on the coefficients of variation of the time intervals of receipt of requests and their servicing in the system, we obtain a significant reduction in the average waiting time in systems with shifted distribution laws.
Background. Spiral light beams are of great interest for practical applications in optics and photonics. This study investigated the efficiency and quality of spiral light beams generated using a holographic method. Aim. To investigate the influence of the line shape of the diffraction grating of holograms on the specified parameters of the reconstructed spiral light beams. Methods. Numerical simulation of spiral light beams and their experimental implementation using a holographic method using a phase liquid crystal spatial light modulator. Energy efficiency and performance criteria such as mean-square error, peak signal-to-noise ratio, and structural similarity coefficient were evaluated. Results. It has been experimentally demonstrated that the type of diffraction grating line profile significantly affects the quality of the generated spiral beams. It was found that beams reconstructed using holograms with sawtooth grating lines are characterized by a more uniform structure and higher energy efficiency than holograms with sinusoidal grating lines. Quantitative analysis confirmed the qualitative observations: for holograms with sawtooth grating lines, the values of the mathematical criteria are, on average, 10–30 % better, and the efficiency is twice as high. Conclusion. It was found that the sawtooth profile of the diffraction grating line of the hologram provides higher beam reconstruction accuracy and energy efficiency compared to the sinusoidal profile.
Background. Controlling the radiation pattern of an array by varying the aperture geometry is a classical problem in antenna theory. Previous studies have shown that abandoning strict periodicity and varying the relative positions of the elements can reduce sidelobe levels. However, in most works geometric modifications are considered as a means of global radiation-pattern optimization, whereas the possibility of reducing the sidelobe levels by small shifts of a finite number of elements has not been described analytically in sufficient detail. Aim. Investigation of the possibility of suppressing a selected sidelobe local maximum of the radiation pattern of a planar phased array by small shifts of the aperture elements, as well as derivation of the analytical relations describing the variation in the level of the selected maximum and determination of the element-shift laws that provide the greatest reduce of the sidelobe. Methods. The study uses the representation of sidelobes as stationary points of the power function, an asymptotic expansion of the array factor with respect to small shifts of the element coordinates, methods for differentiating complex functions, and the method of Lagrange multipliers. Results. An analytical model for changes in the level of a selected non-degenerate sidelobe local maximum with small shifts of a finite number of elements of a planar array is obtained. It is shown that, to a first approximation, the contribution of each element is determined only by the projection of its shift onto the direction of deviation of the selected maximum from the main lobe. Analytical laws for the shift of elements are derived under constraints on the permissible shift magnitude and under minimization of the total quadratic norm of shifts. It is established that diffraction sidelobes correspond to the degenerate case; therefore, their attenuation is determined by the square of the element shift. Conclusion. Small shifts of a finite number of elements can be used to suppress a selected side lobe without changing the level of the main lobe. For conventional sidelobes, the level reduction is determined by the element shifts themselves, while for diffraction sidelobes, it is proportional to the square of the shift. The obtained relations define an analytical basis for geometric correction of the aperture for suppressing a selected side lobe and simultaneously determine the limitations of this approach.
Background. In the context of exponential traffic growth and heightened spectral efficiency requirements for fifth and sixth-generation wireless communication systems, multi-user multiple-input multiple-output and Orthogonal Frequency-Division Multiplexing technologies play a pivotal role. Nonlinear precoding methods, particularly Lattice Reduction-aided Tomlinson – Harashima Precoding, have demonstrated high efficacy in suppressing inter-user interference. However, their practical implementation in OFDM-based systems is hindered by an exceedingly high computational complexity, stemming from the requisite application of the lattice reduction procedure to every individual subcarrier. Aim. The Aim of this work is to address the aforementioned problem by developing and investigating a hybrid algorithm that achieves error performance comparable to benchmark Lattice Reduction-aided Tomlinson – Harashima Precoding, while drastically reducing the average computational complexity. Methods. To achieve the stated objective, this paper proposes a hybrid algorithm that integrates Block Diagonalization for the elimination of inter-group interference with Lattice Reduction-aided Tomlinson – Harashima Precoding for the suppression of intra-group interference. The key scientific novelty lies in the proposed mechanism for selective lattice reduction activation. In contrast to conventional approaches, lattice reduction is not ubiquitously applied to all subcarriers but is adaptively employed only for those where the effective channel matrix is ill-conditioned. The condition number of the channel matrix is utilized as the decision metric. Results. Simulation results confirm that the proposed algorithm achieves a bit error rate comparable to that of benchmark Lattice Reduction-aided Tomlinson – Harashima Precoding and substantially outperforms classical Tomlinson – Harashima Precoding, while achieving a significant reduction in average computational complexity. Conclusion. The developed approach represents an effective trade-off between performance and complexity, offering promising prospects for its practical implementation in the base stations of current and future communication systems.
Background. In modern conditions of rapid development of electromagnetic compatibility technologies, radio electronics and radio engineering, the development of effective radio-absorbing materials capable of absorbing electromagnetic radiation in a wide frequency range is of particular relevance, which determines the need for this study. Aim. Development of a technique for parametric synthesis of an optimal piecewise linear permittivity profile for a radio-absorbing inhomogeneous magnetodielectric layer located on an ideally conductive surface providing minimal reflection in a given frequency range. Methods. The study used mathematical modeling of the interaction of electromagnetic radiation with an inhomogeneous layer structure, a modified method of numerical integration of the third order of accuracy, the method of multidimensional optimization of Hook – Jeeves, as well as numerical analysis of the frequency characteristics of the reflection coefficient. Results. As a result of the research, a method for synthesizing the optimal permittivity profile was developed and tested, profiles for incidence angles of 0°, 30°, 45° and 60° were synthesized, frequency characteristics of reflection coefficient modules were obtained and analyzed, and the results were verified by comparison with a homogeneous distribution. Conclusion. The study showed that the developed profiles provide significantly less reflection compared to their homogeneous counterparts, especially at angles of incidence of 45° and 60°. An important advantage is the technological simplicity of the implementation of synthesized profiles. The results obtained form the basis for the development of modern radio-absorbing materials with an extended operating frequency band and improved absorption characteristics, which is of practical importance for creating effective radio-absorbing coatings in various technical devices.
Background. Increasing the efficiency of both degenerate four-wave converters and quasi-degenerate four-wave converters is an important task in multi-wave interactions optics. A method for increasing the efficiency of a quasi-degenerate four-wave converter by imposing feedback on the signal or object waves using a ring resonator is considered. Aim. The amplitude and spatial characteristics of a quasi-degenerate four-wave converter on thermal nonlinearity in a scheme with feedback are analyzed. Methods. To analyze the amplitude reflection coefficient and the half-width of the angles band of the object wave of a quasi-degenerate four-wave radiation converter on thermal nonlinearity in the presence of feedback on the signal or object waves, a numerical method was used based on multiple passage of the signal and object waves of the nonlinear layer in a ring resonator. Results. An increase in the amplitude reflection coefficient and the half-width of the band of angles of the object wave is shown in the presence of feedback on the object or signal waves. Conclusion. The optimal operating mode of the quasi-degenerate four-wave converter is determined taking into account the presence of feedback, in which an increase in the amplitude reflection coefficient is observed.
Background. The development of broadband coatings with low electromagnetic wave reflection values to reduce radar visibility is a pressing issue. Aim. Experimental and numerical investigation of the scattering and absorption properties of a combined structure based on a metasurface with triangular spiral resonators and an ultrathin conductive film in the K-band. Methods. The study was conducted using electrodynamic modeling methods in specialized software packages (Ansys HFSS, CST Studio Suite) and quasi-monostatic measurements in an anechoic chamber. Results. It was found that the metasurface provides anomalous reflection with suppression of the normal component down to −40.5 dB at 17.7 GHz and is capable of forming side lobes of the scattering pattern under oblique incidence. The addition of a nanometer aluminum film (5 nm) provides additional broadband attenuation of up to 20 dB and effectively suppresses side lobes, ensuring a stable reduction in reflection in the 8 GHz band at angles of incidence up to 75°. Conclusion. The developed combined structure demonstrates a stable effect of spatial energy redistribution and resistive absorption, confirming the promise of such hybrid coatings for creating broadband low-reflective materials.
Background. The efficiency of unmanned aerial vehicle (UAV) applications in agriculture, logistics, and infrastructure monitoring directly depends on their flight endurance. Modern lithium-ion batteries, with a specific energy density rarely exceeding 0,25 kWh/kg, limit aircraft autonomy to 25–40 minutes, which is insufficient for complex multi-hour missions. The increase in takeoff mass associated with higher battery capacity negates gains in flight time, necessitating a transition to alternative power plants with significantly higher energy density. Aim. This work aims to provide a systematic analysis of hydrogen fuel cell application as a key technology for a multifold increase in UAV flight endurance and to identify the technological barriers preventing their widespread adoption. Methods. A comparative analysis of the operational characteristics of lithium batteries, internal combustion engines, and hydrogen systems based on proton exchange membrane fuel cells (PEMFC) was conducted. The principles of designing hybrid power schemes were examined, and the efficiency of various on-board hydrogen storage methods–including compressed gas, cryogenic liquid, and solid-state storage–was evaluated. Results. It was established that hydrogen systems provide a specific energy density of 800–1500 Wh/kg, enabling a 5- to 10-fold increase in UAV flight endurance compared to lithium batteries. The necessity of utilizing a hybrid configuration with a buffer battery to compensate for peak loads during takeoff and maneuvering was justified. It was found that composite high-pressure cylinders are the primary practical solution at the current stage, whereas cryogenic and sorption storage require overcoming challenges related to reducing the mass of auxiliary equipment and the complexity of thermal management. Conclusion. Hydrogen fuel cells represent the most promising solution for professional UAVs, combining high autonomy with low acoustic signature and high reliability. The successful implementation of this technology requires focused efforts on developing lightweight hydrogen storage systems, improving the efficiency of auxiliary components (Balance of Plant), and establishing a refueling infrastructure.
Background. Currently, Software-Defined Radio receivers are widely used for weak-signal reception, radio monitoring, and scientific research; however, their sensitivity is often limited by a high intrinsic noise figure. Methods. This paper explores a method for increasing the sensitivity of the low-cost ADALM-PLUTO SDR receiver in a wide frequency band of 70–6000 MHz by using external Low-Noise Amplifiers. A comparative experimental study of the amplifiers’ influence on the parameters of the receiving path is conducted. A Rigol DSG3136B-IQ generator is used as a reference signal source, generating a test signal with a fixed level of –130 dBm, which allowed for an objective assessment of the change in the signal-to-noise ratio at the system output. The theoretical part of the study is supported by calculations using the Friis formula, predicting an improvement in the noise figure of a cascaded system. Results. The results demonstrate a significant increase in sensitivity when using external amplifiers, while their frequency characteristics are revealed. Conclusion. The practical significance of this work lies in providing engineers and researchers with sound recommendations for selecting the optimal Low-Noise Amplifiers to expand the capabilities of low-cost Software-Defined Radio receivers in various frequency ranges.
Background. The metamaterials using significantly expands the microwave devices capabilities. Chiral metamaterials are actively used in the creation of frequency- and polarization-selective diffractive and waveguide structures. Aim. We calculate the frequency dependences of the permittivity and chirality parameter of a metamaterial consisting of a uniformly distributed set of randomly oriented complex particles consisting of rectangular and S-shaped stripes (chi-particle) in this work. Methods. The mathematical model of a chiral metamaterial based on chi-particles is constructed in this work. Model is based on the quasi-static approach as well as using the Lorentz and Condon dispersion models taking into account material dispersion, dielectric and magnetic resonances in the chiral metamaterial. Results. The dependences of the permittivity, chirality parameter, effective refractive index and propagation constants of waves with right- and left-handed circular polarizations in the chiral metamaterial was conducted. The dependences of the chiral particle resonant frequency on its geometric dimensions were obtained. Conclusion. The data obtained as a result of the calculations can be used in the development of frequency-selective reflective surfaces and layers based on chiral metamaterials.
Background. Antennas are usually measured at the center of metal sheet; thus, its characteristics can be significantly different from set ups at real object. Aim. Research the effects of mobile object shapes and mounting places at ultrawide band antennas irregularity of the radiating patterns in horizontal (azimuthal) plane at an elevation angle of 0°, in order to determine the optimal antenna design and its location. Methods. Computer modeling of radiation patterns in the azimuth plane at an elevation angle of 0° using the finite element method with software ANSYS HFSS 2014.0.2 and comparison of the results obtained depending on the location of the antenna, the type of object, and the type of antenna. Results. It shows a) the electromagnetic characteristics of ultrawide band antennas, like gain in the horizon at various locations on mobile objects; b) the dependence of the irregularity of the radiating patterns from ultrawide band antenna design and the mobile object type, because an asymmetrical and symmetrical antenna will behave differently; c) models of symmetrical and asymmetrical combined ultrawide band antenna, which radiating element is divided into sections for emitting a certain frequency range and only one matching device is used for the entire operating range; e) comparative graphs of the irregularities of the radiation patterns depending on the location of the ultrawide band antenna on the object. Conclusion. An optimal design of a combined ultrawide band antenna is proposed and recommendations are given for antennas installing at mobile objects.
Background. The vision system signal processing is used for space-brightness parameters estimation. It allows object detection and recognition, linear and angular dimensions estimating. A universal method that simultaneously satisfies the requirements for speed and accuracy of parameter estimation does not currently exist. But there are methods that can be used to solve them. The actual problem is method choosing which provides minimum computational cost (the important characteristic for real-time systems) for restrictions imposed on the task. Aim. The aim is methodology of method choosing with minimal computational cost. Methods. The computational cost of the methods was assessed based on the number of hypotheses corresponding to the tested sets of matching parameters. Optimization solutions using directed search algorithms were also included for the computational cost. Results. The result is mathematical expressions for determining the methods computational cost and the methodology. The practical significance is reducing the algorithms development time by method choosing that ensures minimal processing time under constraints. Conclusion. This methodology will be useful for machine vision systems developers, reducing research time when searching for high-speed data processing methods and algorithms. Further research will focus on complementing these processing methods, as well as exploring ways to reduce the computational cost of individual processing stages.
Background. Waves with a doubled reversed wavefront obtained by six-wave mixing are used in adaptive optics and real-time image processing. It is necessary to know how the characteristics of such a reversed wave are affected by the nonlinear medium parameters and the spatial structure of the pump waves. Aim. To analyze the quality of the doubled reversed wavefront in a degenerate six-wave mixing in a parabolic waveguide with resonant nonlinearity, provided that one of the pump waves excites the zero mode of the waveguide, and the amplitude distribution of the other pump wave at the waveguide edge is described by a Gaussian function. Methods. The effect of the single-mode pump wave intensity and the Gaussian pump wave radius on the half-width of the object wave amplitude modulus has been studied numerically, using a wave from a point source as a signal wave. Results. The dependences of the half-width of the object wave amplitude modulus on the single-mode pump wave intensity and Gaussian pump wave radius are obtained. Conclusion. It is shown that an increase in the single-mode pump wave intensity leads to a deterioration in the double wavefront reversal quality. With a decrease in the Gaussian pump wave radius, the quality of the double wavefront reversal improves.
Background. In devices for digital processing of acoustic (sound) signals, various physical processes and the signals reflecting these processes undergo transformations. In signal converters, due to the nonlinearity of their characteristics, nonlinear signal distortions arise. Each converter contributes to signal distortions, making the task of assessing the resulting nonlinear distortions in digital processing of acoustic signals relevant. Aim. To analyze signal conversion processes in digital processing and develop a methodology for calculating the arising nonlinear signal distortions. Methods. Chebyshev polynomials, the sampling theorem, the method of ordinates, as well as methods of permutation and convolution of the spectrum of time-discretized signals were used for the analysis and quantitative assessment of nonlinear distortions. Results. It is shown that as a result of signal discretization and the accompanying spectrum convolution, higher harmonics of the signal, which arise due to the nonlinearity of converter characteristics and for which the conditions of the sampling theorem are not met, fall within the frequency range of the fundamental signal. Conclusion. It has been established that the nonlinear distortion coefficients in digital processing do not exceed the magnitude of the differential nonlinearity of the resulting transfer characteristic of all converters included in acoustic signal digital processing devices.
Background. The formation of specified spatial distributions of the electromagnetic field is a relevant problem of modern antenna technology. Of particular importance is field control in the near-field zone, where it is required not only to generate directional radiation, but to ensure the localization of electromagnetic energy in one or more specified areas of space. Such problems arise in signal transmission systems, electromagnetic exposure applications, microwave material processing, and medical technologies, etc. Aim. Development and investigation of an algorithm for synthesizing the amplitude-phase distribution of excitation currents of a linear antenna array for the formation of a multifocused electromagnetic field with a given location of maxima in the near-field zone. Methods. The theoretical description of the antenna array field as a superposition of the contributions of individual radiating elements and numerical modeling are used, which implements an algorithm with the selection of amplitude-phase coefficients according to the criterion of minimum deviation from a given field distribution. Results. The difference distributions of the first and second types, providing transverse and longitudinal separation of radiation maxima, are investigated. An algorithm of amplitude-phase synthesis has been developed, which makes it possible to select the amplitudes and phases of excitation of antenna array elements according to a given quality criterion. The simulation results confirmed the possibility of forming both symmetric and asymmetric multifocused field distributions. Conclusion. The proposed approach makes it possible to consider difference distributions as a special case of a more general multifocusing problem and expands the possibilities of controlling the electromagnetic field in the near-field zone of a linear antenna array. Using the principles of synthesizing the required amplitude-phase distributions allows you to set the position of several focal areas, regulate their relative levels and reduce the influence of unwanted maxima. The results obtained can be used in the design of antenna systems designed to generate local maxima of the electromagnetic field in limited areas of space.
Background. Ionospheric information radio channels in the high-frequency range were previously widely used for radio communication and broadcasting, including international broadcasting. The international broadcasting system was designed, systematically developed, and expanded over more than half a century and provided round-the-clock radio broadcasting in the high-frequency range to virtually all countries. Technically, this was realized through the construction of several dozen transmitting centers and radio stations for foreign radio broadcasting, based throughout the territory of the Union State. Currently, the possibility of technically implementing ionospheric delivery schemes for high-frequency signals by numerous radio stations has been irreversibly lost. Aim. The urgent problem of accelerated restoration of long-distance radio broadcasting is solved by developing a method and universal technical means for creating fan-shaped ionospheric radio channels. Methods. The problem can be solved by using antenna systems with mechanical positioning. They make it possible to significantly reduce the number of antennas per transmitter, while maintaining the ability to maintain a daily frequency schedule. Results. Analysis and research of the current situation revealed the possibility of incorporating a logical, classic antenna system design for similar situations into the transmitting site. This design, in the simplest case, contains two common-mode horizontal band antennas, which rotate horizontally to create fan-shaped radio channels. This can be achieved by moving them along an arcuate trajectory, for example, along a common double-rail arcuate track. The dimensions and curvature of the rail section are selected based on the profile and dimensions of the selected site, operational requirements, and, most importantly, the availability of antenna sectors in which fan-shaped radio channels are formed. Examples are provided of how a single antenna system can provide Western Europe with fan-shaped interval information service with radio signals, and the possibility of providing information service to a small number of antenna systems in adjacent territories along the Russian border with radio signals to a depth of up to 3,500 km are also illustrated. Conclusion. The presented method for forming fan-shaped ionospheric radio channels, in combination with the transmitting site as a tool for implementing the method, is protected by a patent. They enable the gradual creation of multifunctional transmitting sites for the formation of fan-shaped ionospheric radio channels, focused on radio broadcasting or radio communications, jamming, or the delivery of passive radar signals using single-hop technology. This solves a significant number of problems typical of long-range radio broadcasting centers of the past.
Background. Classical network topologies, such as the two-dimensional mesh, impose constraints on the scaling of photonic neuromorphic processors, leading to exponential growth of optical losses, a quadratic increase in occupied area, and a linear increase in latency with the number of nodes. Biological neural networks demonstrate an alternative, evolutionarily optimized principle for constructing their architecture, utilizing self-similar and hierarchical laws to ensure high connectivity with a short average path length. Therefore, the study and adaptation of such fractal topologies represent a relevant task for overcoming the scaling barriers of photonic neuromorphic computing systems. Aim. To perform a theoretical analysis and quantitative comparison of the main parameters of self-similar topologies to substantiate the boundaries of their applicability in scaling photonic neuromorphic processors; to formulate recommendations for the selection and adaptation of interconnection architectures. Methods. A systematic comparative analysis of 13 types of network topologies was conducted, including stochastic (fractal dendrites, neural clusters, small-world network, scale-free networks) and deterministic fractal structures (trees, Sierpinski carpets, Hilbert curve, Koch snowflake), as well as traditional ones. For each topology, five key parameters were calculated and analyzed at scales up to N=107 nodes: diameter, average path length, clustering coefficient, critical failure probability, and maximum optical losses. Based on multi-factor comparison, a final classification of topologies according to their practical applicability was performed. Results. It was established that topologies with logarithmic diameter scaling (small-world network, fractal trees) provide minimal latency and optical losses. However, many deterministic fractals have zero local clustering, while stochastic models are technologically difficult to implement. Based on a scoring assessment across five criteria (scalability, clustering, reliability, maximum optical losses, technological implementability), the «small-world network» topology was recognized as optimal. To optimize the balance of key characteristics, a concept of hybrid «engineered fractals» was proposed – deterministic truncated hierarchies combining a fractal backbone for global connections with regular clusters at the local level. Conclusion. It is shown that the potential of fractal topologies for scaling photonic neuromorphic systems is specific and realizable primarily through their adapted, hybrid forms. The main recommendation for designing large-scale processors is to use a deterministic hierarchical implementation of the «small-world network» or «engineered fractals», which allows combining logarithmic latency scaling, high fault tolerance, and technological implementability in planar integrated photonics.
Background. In wireless mobile communications, there are often situations when several radio transmitting devices operate on a single antenna system in several frequency bands, and therefore there is a need to create efficient multi-frequency antenna systems operating in two or more frequency bands. One of the approaches to creating such multi-frequency antenna systems is the use of fractal radiators of various spatial geometries. In addition, the use of chiral metamaterials in the designs of such antennas makes it possible to increase the spectral efficiency of the entire system. Aim. Investigation of the possibilities of increasing the spectral efficiency of modern radio communication systems using MIMO technology by using antenna systems based on chiral metamaterials with fractal emitter geometry. Methods. For calculating the characteristics of antenna systems with fractal emitter geometry, electrodynamic modeling methods and software complexes based on them are used. Results. The characteristics of antenna systems with fractal emitter geometry are calculated. It is shown that such antennas have multi-frequency properties. Frequency dependences of spectral efficiency are determined when using two-element antennas with different fractal radiators. It has been established that in most cases there is an increase in spectral efficiency. Conclusion. The radiating structures under consideration can be used as the basis for creating antenna systems for modern radio communication systems using MIMO technology. However, it should be noted that some technical solutions of radiating structures are unlikely to find application in broadband radio communication systems, since they have relatively small operating frequency bands.
Background. A considerable number of fractal features are currently known, each individually characterizing the scaling, singular, directional, and multifractal properties of a texture. Therefore, for solving a range of thematic processing tasks for the same image, it becomes necessary to apply various texture-fractal features, which possess different informative and discriminatory power. From both the theoretical and practical perspectives of digital image processing, this approach fails to meet the efficiency requirements for a broad range of applications. Aim. To substantiate a unified processing method for multidimensional data from aerospace monitoring radar systems. This method is based on fractal features that are universal across different feature spaces of multidimensional and multi-parameter radar images of aerial and ground targets, formed under jamming conditions, with the goal of automating the interpretation process. Methods. The directional morphological multifractal signature method employed in this work is based on the iterative morphological formation of «upper» and «lower» covers using dilation and erosion operations, respectively, with a linear structuring element rotated through a discrete range of angles. The procedure involves calculating the «volume» between the original image and the iterative covers, estimating the surface area, computing the generalized statistical sum as a function of the distribution of the q-th order scaling moment measure of the multifractal set at each analyzed scale, and forming multifractal signatures by determining the generalized statistical sum between adjacent analysis scales, with final value correction based on the predominant texture direction. Results. A concept of multidimensional radar imagery is proposed, with a justification for the maximum possible dimensionality of the data array formed by a synthetic aperture radar. The method allows for the simultaneous estimation of nearly all known fractal parameters (with the exception of lacunarity) while accounting for anisotropy, and generates their corresponding images using a unified scientific and methodological framework. This eliminates information loss associated with the separate computation of all features by different methods and achieves a synergistic effect from the application of this approach. Based on the proposed method, technologies for generating a universal fractal feature for parametric, multiband, and polarimetric radar images have been developed. Conclusion. Despite the substantial computational overhead required to implement the proposed method, this approach enables the use of a universal set of fractal features for the entire diversity of radar imagery. This universality is achieved irrespective of the imagery’s dynamic range and the physical nature of electromagnetic wave scattering across various frequency bands and polarizations, while preserving high reliability and informational content. The results of texture-fractal processing of two-dimensional, multiband, and polarimetric radar images formed by Synthetic Aperture Radar systems demonstrate high reliability and completeness of the extracted information.
Background. The article contains the brief bibliography of works of a major Russian scientist – radiophysicist Alexander Alexeevich Potapov who made a great contribution into development of fundamental and applied investigations in the field of radar, propagation and scattering of radio waves, signal processing, fractal and texture analysis, fractional operators, scaling and dynamic chaos. Aim. The aim is the presentation of main publications and works of A.A. Potapov. Methods. A.A. Potapov created a widely known in the world the Russian scientific school of fractal methods. A.A. Potapov and his disciples proposed a new local dispersion method of measurement of fractal dimension and corresponding fractal signatures of signals, images and wave fields. A.A. Potapov created a new method of modern radar – fractal-scaling or scale – invariant radar. Results. Investigations carried out by A.A. Potapov are a priority in the world and are the basis for development and practical application of fractal-scaling and texture methods of modern radio physics and radar. Results obtained by A.A. Potapov and disciples are perspective to solve modern problems of radio physics, radio engineering, radar, communication, photonics, artificial intelligence and control. In the beginning of May 2024 A.A, Potapov formed a concept or a paradigm «Multi-profile radio». The paradigm is based on the fundamentally new approach to joint use of physical properties of electromagnetic waves in a wide frequency range and versatility of topology of fractal sets. Previously in 2022 – 2024 there was a cycle of works in Russia and China on possibility and necessity of unification of roadmaps «Fractals», «Photonics» and «Artificial intelligence» for end-to-end technologies. The final purpose is fundamentally new architecture of radio systems and radio channels. «Smart» or Intelligent radio environment is a wireless environment that turns into intellectual reconfigurable space and plays an active role in transmission and processing of information and makes a more reliable exchange between the transmitters and the receivers. The concept of «Smart» radio environments is directed to create a distributed intelligent platform of wireless connection, probing and calculations that connects physical and digital worlds. Conclusion. Broad erudition, work capacity, purposefulness brought to A.A. Potapov deserved authority and fame in the world scientific community.
