Search

In today's competitive market, it is crucial to continually improve antenna manufacturing technologies to keep up with the increasing demands. Researchers can utilize numerical methods to create novel and highly effective antenna designs, pushing the boundaries of antenna engineering. This paper considers two approaches to efficiently model and design sparse wire-grid antennas. The main idea is to create an optimal wire structure that closely approximates the current paths in the antenna while maintaining its integrity with minimal mass. This structure can be used in further simulations with controlled characteristic accuracy and less resources. In this study, these approaches were applied to modelling horn, conical horn, and reflector antennas. The verification was conducted by comparing their results with those obtained from numerical and experimental tests for the same antenna designs. The findings demonstrated good agreement between the results. In addition, we investigated the impact of using these approaches on the antenna characteristics and found that they can enhance the performance of certain characteristics while reducing costs in manufacturing and modelling. [ABSTRACT FROM AUTHOR]

The article presents the results of a study of a modal filter (MF) based on a microstrip line (MSL) with two side conductors grounded at both ends. For the first time, the quasi-static simulation and measurements of the filter are conducted with two devices, and the results are compared. Frequency dependences of |S11| and |S21| are measured and calculated in the range from 0 to 10 GHz. At the MF output, the time response to an ultrashort pulse (USP) was analyzed. It was experimentally proved that the performed quasi-static simulation was correct. The simulation and measurement results showed remarkable consistency. The proposed MF provides the protection of electrical circuits from USP by decomposing it into two pulses with the amplitudes that are more than three times smaller. This confirms that such MF obtained simply by adding to a MSL two passive conductors grounded at both ends can be used to create simple and cheap protection, for example, of critical radioelectronics against powerful intentional USP created by electromagnetic weapons. [ABSTRACT FROM AUTHOR]

The article proposes a generalized algorithm for evaluating the shielding effectiveness (SE) of electronic equipment enclosures. The algorithm is based on a number of analytical models that use equivalent circuits to obtain SE values. The article begins with a brief review and interpretation of the mathematical formulation used in the algorithm. Then, we describe the proposed algorithm using flowcharts, and we perform its validation. The validation results show that the proposed algorithm has acceptable accuracy and gives SE values comparable to numerical methods or measurements, with much less time costs. The last part of the article presents the software developed to evaluate SE based on analytical models. [ABSTRACT FROM AUTHOR]

Modal reservation (MR) allows both increasing the circuit reliability and implementing the effect of modal filtering. The paper presents the study of a printed circuit board (PCB) with MR with the reference conductor in the form of side polygons. The structure is analyzed by quasi-static simulation, and the minimization of the maximum ultra-wideband pulse amplitudes at the far end of the structure after failures is first estimated. Using the heuristic search, the parameters for the PCB structure before and after failures are obtained. It is shown that, before failures, the maximum amplitude (Umax) does not significantly change under the condition of matching and at fixed values of loads. However, after failures, the Umax changes. For this structure, with increasing delay differences between pulses, Umax after failure 3 increased. It is shown that with obtained values of the geometric parameters, amplitudes of decomposition pulses change differently before and after failures. A prototype of the PCB was designed based on this study. [ABSTRACT FROM AUTHOR]

This work focuses on the study of shield systems consisting of nested enclosures. In the first step, using FDTD simulations and measurements in an anechoic chamber, we investigate the shielding effectiveness (SE) of the system of two nested rectangular enclosures in the frequency range of up to 3 GHz. It is shown for the first time that for a number of frequencies, the SE of the nested shields can be improved by 40–50 dB due to the asymmetric arrangement of the enclosures, their electrical connection, and the mutually perpendicular arrangement of the apertures. Next, we analyze the emissions from the electromagnetic radiation sources in the presence and absence of a nested shield system. The results show that a nested shield system may not attenuate the emission amplitude but increases it by more than 58 dB at the resonant frequencies of the enclosures. Then, we prove that a single enclosure can have a higher SE than the same enclosure as a part of a poorly designed nested shield system. The final part of the article formulates practical recommendations for the design of nested shield configurations. [ABSTRACT FROM AUTHOR]

Since the end of the 19th century, radioelectronic devices (REDs) have actively penetrated into all modern community spheres. Achievements in the fields of radio engineering and electronics, as well as computing, information, telecommunications, and other technologies, have greatly contributed to this. The main elements of REDs are antennas and microwave devices. For example, linear (wire) antennas are the basis of long-distance communication agency networks of various law enforcement agencies and departments. The manufacturing of REDs requires the regular and rapid appearance of more and more advanced types with minimal costs. At the same time, the design complexity of REDs and the tightening of EMC requirements caused by the growth of upper frequencies of useful and interfering signals, the mounting density, as well as the capabilities of generators of intentional electromagnetic impacts, together with the need to take into account inter-element, inter-unit, and inter-system interference, require more and more accurate designs of REDs. However, this becomes impossible without computer modeling, which saves the time and financial resources required for their development, as well as to evaluate the correctness of the proposed technical solutions. During the design process, as a rule, a multivariate analysis or optimization of the product is performed. In this case, methods of computational electrodynamics (one of which is the method of moments) are used. They are based on the replacement of continuous functions with their discrete analogues (construction of a grid), which reduces the problem to the solution of a system of linear algebraic equations (SLAE). The problem's complexity depends on the complexity of the SLAE solution, which is determined by its order (which in turn is determined by the complexity of the simulated object and its surrounding area) and by the number of the required SLAE solutions for each problem (determined by the upper frequency of the signal, the number, and range of the optimized parameters). This dramatically increases the computational cost, which becomes the main constraint for the optimal design. Therefore, reducing the computational cost for the analysis and optimization of RED elements (in particular, linear antennas) is an important scientific problem. Meanwhile, finding new antenna structures that meet all the desired features (low price, required characteristics, manufacturable design with small dimensions and windage, etc.) is no less important today. One of the promise solutions for these problems is using a wire grid and sparse antennas for modeling and constructing antennas. Since the last century, a lot of research has been performed on them. The aim of this paper is to review their history and the main related aspects such as computational, acceleration, and optimization used methods, the fields of their application, and their evolution to this moment. In addition, this paper provides a possible future implementation of wire-grid and sparse antennas from the authors' point of view by presenting a new method that is under research to obtain effective wire sparse antennas. [ABSTRACT FROM AUTHOR]

This article presents the results of an experimental study of a structure with single modal reservation (MR). The decomposition of an ultrawideband (UWB) pulse in such a structure before and after failures has been demonstrated for the first time. For this case, authors used two bell-shaped pulses with a total duration of 0.15 and 1.5 ns. The frequency dependences of the transmission coefficient magnitude |S21| were measured for the manufactured prototype in the range from 10 MHz to 18 GHz. The results demonstrate that the structure before and after failures acts as a low-pass filter. To confirm the results of the experiment, its numerical simulation was carried out using two approaches: quasistatic and electrodynamic. In doing so, we took into account losses in conductors and dielectrics. To numerically estimate the criticality of the voltage waveforms obtained during the experiment at the output of the reserved circuit before and after failure, we calculated the N-norms. The simulation and experimental results in the time and frequency domains agree quite well. It was shown experimentally that after failures the maximum changes in the cutoff and the resonant frequencies are 45% and 19%, respectively. This suggests that after failures, the results may not coincide with the predicted ones, which must be taken into account when designing real structures with MR. It was found that in the time domain after failures, the maximum amplitudes of the decomposition pulses at the far-end of structure with a single MR change, and these changes depend on the duration of the UWB pulse at the input. This influence is explained by the length of the traces to SMA connectors. If the double delay in the trace is greater than the total pulse duration, then after failures, the amplitudes will not change, since the reflected pulses will not be superimposed on the main ones. However, as the length increases, the UWB pulse will be superimposed on the main ones and will change the maximum amplitude. This effect must be taken into account during design process as it can affect the interference immunity and functional safety of the device. This is shown in the analysis of N-norms. [ABSTRACT FROM AUTHOR]

The article presents the results of calculating time responses of a meander line (ML) turn to pulse excitation. The responses were calculated at the ML nodes analytically and numerically, and demonstrated coincidence. Besides, the created prototype of the ML turn was measured and showed good qualitative and acceptable quantitative agreement with the simulation results. Analytical models were found to be promising since they may significantly accelerate the design of such MLs in contrast to numerical methods which provide costly multivariate simulation of the time response during optimization. [ABSTRACT FROM AUTHOR]

The study considers the problem of ensuring electromagnetic compatibility of EMI-based functional destruction means with other radioelectronic equipment as part of a complex for countering unmanned aerial vehicles. To solve this problem, it is proposed to create a methodology that combines a set of diverse approaches and methods. This study focuses on the use of hollow and thin passive conductors, the use of a magnetodielectric in a reflection symmetric modal filter, the use of reflection symmetric structures for decomposing the train of ultrashort pulses (USP), and the use of a meander line as a protective means against USPs. The main results that are expected to be obtained using the proposed approaches and methods are outlined. [ABSTRACT FROM AUTHOR]

This work presents a detailed, comprehensive study of a new structural design of protective devices with a circular cross-section (CS) (protective cables) for protecting equipment against ultra-wideband (UWB) pulses. Multiconductor structures with 2–5 conductors with and without a protective shield are considered. The disadvantages of using symmetric configurations of protective cables are shown. Their simulation, multivariate analysis, and optimization through heuristic search, as well as evolutionary strategies, were carried out. Optimization was carried out according to the amplitude (to minimize the maximum voltage level at the output of the structures) and time (to maximize the duration of the exciting signal) criteria. The optimization results allowed for increasing the duration and overall attenuation of the exciting UWB pulse. The article shows the possibility of improving the characteristics of such structures through their cascade connection, both among themselves and with strip protective structures. The results of parametric optimization of such structures are presented in the range of real (used in practice) geometric and electrophysical parameters in terms of amplitude and time criteria, as well as the matching criterion. The article also presents the developed prototypes of protective structures with a circular CS of three types: circular 3-conductor cable, flat 3-conductor cable, and circular 4-conductor cable. The experimental results describe how these prototypes were developed and created and confirm the feasibility of these protective structures to decompose the exciting pulse signal, which was previously shown only in simulation. Finally, it is shown that the use of asymmetry in the proposed cable structures can improve their protective characteristics. [ABSTRACT FROM AUTHOR]

The paper presents new analytical models for calculating the time response of a meander line (ML) turn with symmetrical cross-section and terminations to a pulse excitation. For the first time, the models were used to derive simple analytical models to equalize voltage amplitudes of the first pulses at the ML turn output: two pulses in homogeneous and three pulses in inhomogeneous dielectric filling. The obtained models were validated by quasistatic simulation. As a result, we theoretically proved that the maximum pulse amplitudes at the ML output are equal to 61.8% and 41.4% of the input amplitudes for the lines with homogeneous and inhomogeneous dielectric filling, respectively. The results could considerably simplify a computer-aided design, allowing for accelerated optimization of these structures without costly multivariate calculation of time response by numerical methods. [ABSTRACT FROM AUTHOR]

The paper proposes a semi-analytical approach to improve the analytical method of an enclosure equivalent circuit. This approach is based on the application of a quasi-static analysis of coplanar striplines in the calculation of the Zap impedance for an enclosure wall with an aperture. Using this approach in conjunction with existing analytical models, the shielding effectiveness can be calculated for an enclosure with an aperture filled with an arbitrary dielectric or magnetic content. The study also presents the results of extensive validation of the proposed approach in the frequency range up to 3 GHz. [ABSTRACT FROM AUTHOR]

A quasistatic approach was used to consider the occurrence of additional pulses (APs) in the modal filter (MF) realized on a double-sided printed circuit board, as well as in the three structures obtained from it by removing one reference conductor. It is shown that, for all investigated MFs, the AP delays are determined by a linear combination of per-unit-length mode delays multiplied by the line length. It was found that there are no APs between the pulses of modes with one pass along the line, while they appear with three or more passes. It is revealed that in each of the considered MF structures (except the one without upper-right reference conductor), the APs have greater amplitudes of mode pulses with a triple pass. It was demonstrated that the removal of the reference conductors affects the number, polarity, and amplitude of the APs. [ABSTRACT FROM AUTHOR]

This article describes a new approach to electrostatic discharge (ESD) protection based on usage of a turn of a microstrip meander line (ML). The proposed approach enables decomposing an ESD peak surge with the duration of about 4 ns into a sequence of smaller amplitude pulses. Using a quasi-static simulation of the meander turn time response to the excitation of the IEC 61000-4-2 standard ESD current source, we obtained the condition for such decomposition. In addition, we derived the condition for the overlapping of the additionally reflected odd mode pulse of the negative polarity on the even mode pulse to reduce the amplitude of the last pulse. As an example, the proposed approach is used in investigating the ESD pulse propagation along the ML with various parameters. We also found the optimal value of the turn length for the minimum output ESD voltage, which decreases as the distance between the ML half-turns decreases. The described approach and the formulated conditions provide the improvement of the protection against ESD by decreasing its magnitude by several times. The effectiveness of the new approach is confirmed by the electrodynamic simulation and prototype measurements. The new research results supplement the theoretical framework for ESD mitigation techniques and can be used in designing reliable, light-weight, low-cost, and radiation-resistant ESD protection devices. [ABSTRACT FROM AUTHOR]

An analytical model is proposed for evaluating shielding effectiveness (SE) of a rectangular enclosure populated with conducting plates. The conducting plates are considered as capacitive diaphragms that fill the width of the enclosure, and SE is calculated using the equivalent circuit of the enclosure. The letter presents an improved approach to evaluating enclosures populated with printed circuit boards (PCBs) or plates coated with a composite or radar-absorbing material. The evaluation of the model error was performed when the plate height changed. Both this model and finite element method were used to calculate the SE for enclosures populated with conducting plates, PCBs and the plate coated with a magnetic composite material. The results obtained in the range up to 1 GHz are in good agreement. [ABSTRACT FROM AUTHOR]

In this paper we consider the complexity problem in electronics production process. Particularly, we investigate the ways to reduce sensitivity of transmission line characteristics to their parameter variations. The reduction is shown for the per-unit-length delay and characteristic impedance of several modifications of microstrip transmission lines. It can be obtained by means of making an optimal choice of parameter values, enabling proper electric field redistribution in the air and the substrate. To achieve this aim we used an effective simulation technique and software tools. Taken together, for the first time, they have allowed formulating general approach which is relevant to solve a wide range of similar tasks. [ABSTRACT FROM AUTHOR]

The problem of protecting radio electronic equipment from ultrashort pulses is of utmost importance nowadays since conductive interference poses the biggest danger to its proper functioning. The article considers the issue of protecting equipment by means of modal filters (MFs) and analyzes the structures of multiconductor microstrip MFs. We present the results of a complex study of the possibility to conduct the optimization (both separate and simultaneous) of a multiconductor MF by different criteria and the formulation of the basic (electrical) optimization criteria for MF. We have formulated the amplitude and time criteria for optimizing an MF (with any number of conductors) in an analytical form and obtained a general multicriteria objective function for optimizing an MF by different criteria. As a result, we have formed a hybrid model consisting of heuristic search and GA. The results demonstrated the topicality of further research in this field. [ABSTRACT FROM AUTHOR]

Examines the problem of far-end crosstalk reduction in double-layered dielectric interconnects. Usage of the possibilities in printed circuit boards; Simulation of far-end crosstalk waveforms; Assumption of the calculation of lines parameters.

This work is devoted to the research of new asymmetry effects in symmetric protective structures with triple modal reservation. We analyzed the structures with different cross-sectional locations of the reference conductor: in the center (unshielded structure), around (shielded structure), at the top and bottom (multilayer printed circuit board), and in the form of side polygons (double-sided printed circuit board). First, a preliminary quasi-static simulation was performed in the range of parameters. It was revealed that in all structures, except for the shielded one (in the form of a cable), the deviations of the output voltage amplitude, bandwidth, and frequency of the first resonance were insignificant, whereas in the shielded structure there were significant deviations in the time and frequency responses. The attenuation of the output voltage in relation to the input for each structure was also estimated. In addition, we performed a parametric optimization of the structures under consideration using a heuristic search, which made it possible to improve their characteristics. Finally, the switching order between the conductors in these structures with the original and optimized parameter sets was investigated in detail. The optimal conductor switching order in the case of a component failure was determined, and the best (according to protective characteristics) parameter configuration for each structure was found. [ABSTRACT FROM AUTHOR]

The paper presents some experimental results on unusual propagation of an ultrawide band (UWB) pulse in low-voltage three-conductor power cables. For cables of flat cross section, the results confirm the possibility of modal decomposition of the pulse into two low level pulses. However, this phenomenon does not occur in cables of circular cross section. [ABSTRACT FROM AUTHOR]

For the first time, the paper considers in a unified work the possibility of the appearance of additional pulses in various structures based on modal filtration technology, which is used to improve protection against ultrashort pulses (USP). We analyzed meander lines (ML) with broad-side coupling, structures with modal reservation (MR), reflection symmetric MLs, and modal filters (MF) with a passive conductor in the reference plane cutout and obtained the following results. It was found that the main reason for the additional pulses to appear in these structures is the introduction of asymmetry (of the cross-section, boundary conditions, and excitation). It is theoretically and experimentally established that additional pulses are a new resource for increasing the efficiency of protective devices with modal decomposition, but the highest effectiveness could be achieved through careful optimization. [ABSTRACT FROM AUTHOR]

This study highlights the importance of detecting and localizing useful and interference signal extreme points in multiconductor transmission lines (MCTL) by developing a new approach for detecting and localizing signal extreme points in MCTL networks of arbitrary complexity. A radio-electronic component is presented as a network consisting of a number of connected MCTL sections. Each MCTL section is divided into segments and the number of segments is set by the user. The approach is based on a quasi-static calculation of signal waveforms at any point (segment) along each conductor of an MCTL. The block diagrams of the developed algorithms are presented. Using the approach, a number of investigations have been done which include the following: the signal maximum detection and localization in the meander lines with one and two turns, the influence of ultrashort pulse duration on localization of its extreme points in the printed circuit board (PCB) bus of a spacecraft autonomous navigation system, the influence of ultrashort pulse duration on localization of crosstalk extreme points in the PCB bus, and the simulation of electrostatic discharge effects on the PCB bus. There are also some investigations with optimization methods presented. A genetic algorithm (GA) was used to optimize the influence of ultrashort pulse duration on localization of the pulse and crosstalk extreme points in the PCB bus. Furthermore, the GA was used to optimize the PCB bus loads by criteria of the peak voltage minimization. A similar investigation was carried out with the evolution strategy. The obtained results help us to argue that the signal extreme points can be detected both in structures with different configurations and applying different excitations. [ABSTRACT FROM AUTHOR]

The paper considers the protection of critical radio-electronic equipment (REE) from ultrashort pulses (USP) by means of modal filters (MFs). A new approach to improve modal filtration by using reflection symmetry is analyzed. The results of a sophisticated research into protective devices based on reflection symmetric MFs are presented: improving the characteristics of four MFs through optimization both by one and simultaneously by several criteria; calculating the per-unit-length time delays matrix of a reflection symmetric MF using the obtained analytical expressions; calculating the time and frequency responses of an MF with and without losses in conductors and dielectric; developing the laboratory evaluation board; analyzing the effect of moisture protection on the characteristics; analyzing the features of reflection symmetry structures; comparing microstrip and reflection symmetric four-conductor MFs. The obtained results allow us to argue that the reflection symmetric MF protects REE from a USP due to its decomposition into a sequence of pulses with pairwise equalized voltage amplitudes and close time intervals between decomposition pulses with an attenuation coefficient of four times with a controlled bandwidth of a useful signal. This research helps take advantage of the possibilities of using the symmetry to improve modal filtering and opens the ways to create a large number of new MF designs, applying only the principles of the symmetry described in the work. [ABSTRACT FROM AUTHOR]