https://radioelektronika.org/issue/feedRadioelectronics and Communications Systems2024-02-26T13:51:03+02:00Fedor Dubrovkafedor.dubrovka@gmail.comOpen Journal Systems<p><em>Radioelectronics and Communications Systems</em>, ISSN 1934-8061 (Online), ISSN 0735-2727 (Print) is a monthly peer-reviewed international scientific journal on electrical engineering, electronic engineering, and electronics. It is English version of the journal <em>Izvestiya Vysshikh Uchebnykh Zavedenii. Radioelektronika</em>, ISSN 2307-6011 (Online), ISSN 0021-3470 (Print). The journal is indexed in SCOPUS, INSPEC, Google Scholar, CNKI, EBSCO Discovery Service, EI Compendex, Gale, Gale Academic OneFile, Gale InfoTrac, INIS Atomindex, OCLC WorldCat Discovery Service, ProQuest Advanced Technologies & Aerospace Database, ProQuest SciTech Premium Collection, ProQuest Technology Collection, ProQuest-ExLibris Primo, ProQuest-ExLibris Summon, VINITI, RSCI. <strong>Сites per Doc. = 0.8</strong> (Cites per Doc. (2y) = Impact Factor WoS, 2019). <strong>SJR = 0.21, Q3, SNIP = 0.51</strong> (Scopus, 2019).</p>https://radioelektronika.org/article/view/S0735272723030044Dual-band microstrip balun with different complex load impedances in frequency bands2024-02-26T12:28:51+02:00Valeriy Oborzhytskyyoborzh@polynet.lviv.uaVolodymyr Storozhvolodymyr.h.storozh@lpnu.uaSergiy Fabirovskyyserhii.y.fabirovskyi@lpnu.ua<p>The paper proposes a circuit and calculation method for dual-band microstrip balun that along with equal-amplitude and counterphase distribution of signal between outputs in two bands, ensures the transformation of complex load impedances, which are different in these bands, into a real value of input impedance of the source. In this case, the matching of device input and outputs is achieved with a high decoupling level of the latter. The proposed structure consists of cascade connection of four sections of coupled lines, two reactive elements that are implemented by stubs and the decoupling links of outputs. Three variants of circuits are presented for implementing the specified structure. The presence of elements in the circuit, the parameters of which can be specified, ensures the flexibility of designing process without any restrictions on values of loading impedances. In addition, the calculation process takes into account the difference of phase velocities of modes of microstrip coupled lines. For checking the properties of the proposed circuit and its designing technique, a microstrip balun for two working bands of frequencies with average values of 1.4 GHz and 2.8 GHz at different complex load impedances was manufactured and experimentally tested. The results of measurements well agree with the results of electromagnetic simulation; they also show that in both bands, the unbalance of amplitudes and phases at the balun outputs does not exceed 1 dB and 10 degrees, respectively, confirming the expediency of using the proposed circuit and its designing method.</p>2023-01-26T00:00:00+02:00Copyright (c) 2024 https://radioelektronika.org/article/view/S0735272723020012Double-layered t-shape loaded hairpin resonator for high performance characteristic dual-band BPF design2023-03-08T01:43:12+02:00Zainab O. Mohammedzainabaoda79@gmail.comRaaed T. Hammedraaed.t.hammed@uotechnology.edu.iq<p>A simple high performance compact dual-band bandpass filter is developed in this paper based on multilayered T-shape loaded hairpin resonator (T-SLHR). The filter circuit is constructed using two substrates. On the first ground plane substrate, two T-SLHRs are analyzed and electrically coupled through a space gap <em>S</em> to accomplish the desired dual passbands. To acquire the filtering response, an input/output grounded hairpin-stub is patterned on a second ungrounded-substrate and broadside coupled to the T-SLHRs. To validate the proposed concept, a dual-band BPF is realized for a multi-wireless network system working at 2.4 GHz and 3.5 GHz center frequencies. Indeed, the T-SLHR is analyzed based on odd-even theory to generate the specified frequencies. Furthermore, a block-diagram to explain the coupling mechanism of the expected filter behavior is suggested. Moreover, the simulated filter is manufactured and its measurement and simulation results are compared and discussed. The produced filter has quite small area less than 126 mm<sup>2</sup>, high skirt roll-off selectivity and good isolation rejection band.</p>2023-01-26T00:00:00+02:00Copyright (c) 2024 https://radioelektronika.org/article/view/S0735272723010065Microwave absorbing composite materials2024-02-26T12:38:45+02:00Yuriy Poplavkoypoplavko@gmail.comDmytro Tatarchukdmitry.tatarchuk@gmail.comYurii Didenkoyu.v.didenko@gmail.comDmytro Chypegind.chypehin-me25@lll.kpi.ua<p>Designing of microwave systems based on composite materials involves the need of thorough understanding of interaction processes of electromagnetic waves with such materials and factors that affect this interaction. Polymer-based composites filled with materials having a high degree of electromagnetic energy absorption make it possible to combine electric properties of composite material with the mechanical elasticity, chemical resistance, and good fabrication properties. Selecting materials and their processing techniques, it is possible to achieve the required properties, both electrodynamic and mechanical. Composite properties are essentially influenced by such factors as the size and shape of filler particles, the volume fraction of filler, etc. Therefore, this paper considers different types of fillers for producing polymer-based composites, namely, magnetic materials, metals, carbon, and dielectrics with high dielectric permittivity. Advantages and disadvantages of the above fillers are analyzed. It has been shown that in the millimeter wavelength range, the relevent composites are those, in which the absorption is implemented due to the inclusion of polar dielectrics into their composition.</p>2023-01-26T00:00:00+02:00Copyright (c) 2024 https://radioelektronika.org/article/view/S0735272723010028Calculation of geometric dimensions of cold cathode surface in high-voltage glow discharge electron sources2024-02-26T12:45:52+02:00Igor Melnykimelnik@phbme.kpi.uaSerhii Tuhaisbtuhai@gmail.comIryna Shvedshvettd@gmail.comM. Yu. Skrypkaimelnik@phbme.kpi.ua<p>The paper proposes a new iterative algorithm for finding the transverse dimension of the cold cathode of high-voltage glow discharge electron guns, based on formulation of a nonlinear equation for the functional dependence of the cathode size on the discharge current and solving this equation using the Steffenson iterative method. A distinctive feature of the proposed calculation method is taking into account the dependence of high-voltage glow discharge current on the plasma boundary position. To obtain the corresponding nonlinear equation, we use the approximate theory of one-dimensional discharge gap and well-known statement of the discharge theory that the anode plasma occupies a definite volume, which is determined by concentration of charged particles, regardless of the geometry of the electrode system. There are specified the geometric parameters of the electronic system of the high-voltage glow discharge with a spherical cathode and a hollow anode, and also well as restrictions on the system of parameters that satisfy the requirements of completeness, consistency, and closure are introduced. On a basis of the numerical analysis of the proposed iterative algorithm convergence process, we show that in case of the restrictions on the introduced parameters system are satisfied, the method convergence is usually ensured. We compare the calculations results of the transverse dimension of the cathode of high-voltage glow discharge guns with correspondent experimental data. The comparative analysis results showed that proposed iterative algorithm application results in the difference between calculations and experimental data does not exceed a few percent. The research results and proposed iterative method for calculating the transverse dimension of the cold cathode of high-voltage glow discharge guns are of great practical value and can be directly used at the initial stage of designing gas discharge guns to assess their technological possibilities.</p>2023-01-26T00:00:00+02:00Copyright (c) 2024 https://radioelektronika.org/article/view/S0735272723020036Computer modeling as instrument for optical locator synthesis2024-02-26T13:12:43+02:00Ya. I. Lepikhndl_lepikh@onu.edu.uaV. V. Yankoyankovova@gmail.comV. I. Santoniivsantoniy@ukr.netV. O. Protsenkoprocenko@merydian.kiev.ua<p>It is proposed a method of generalized computer modeling of optical locators (OL) based on all known methods: amplitude, triangulation, phase and TOF (time of flight), including their dynamic operation in spatial interaction with the object and interference. The method consists of modeling of a number of physical phenomena, which is organized into an algorithm of actions with objects of several computer-aided design (CAD) programs. The effectiveness of intelligent algorithms for processing signals as a main trend to achieve the perfect OL stage is demonstrated. Analysis of the technology for the OL devices synthesis of and its development in retrospect is carried out. The reasons for the growth of computer modeling in the set of tools for current OL design technologies are examined. There is represented the classification and the structured list of methods of computer simulation of OL separate elements. It is described and defined the essence of a new useful tool for analysis of the OL devices operation, which is proposed to call “Generalized PSPICE model of optical location system.” It is described and defined the essence of the method of discrete-time variation of the generalized PSPICE model of the optical location system parameters as a tool of expanding the capabilities of the model. The examples are represented showing the cases where the given model allows to verify the product functionality before its prototyping. The framework algorithm of OL synthesis in form of structured table with illustrated examples of design objects is represented.</p>2023-01-26T00:00:00+02:00Copyright (c) 2024