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.

This paper presents a novel technique for improving modal filter (MF) performance by using an electromagnetic absorber which shows a significant improvement in attenuation of ultra-wideband interference. The authors analyzed the effect of the absorber on the MF performance in suppressing conducted and radiated interferences (in the near and far fields). As an excitation, the authors used an ultra-wideband pulse of 155 ps (at 0.5 level) and then employed $N$ -norms to estimate and characterize the decomposed pulses. It was experimentally demonstrated that the value of $N_{1}$ decreased by a factor of 4.31, $N_{2}$ – by a factor of 6.52, $N_{5}$ – by a factor of 1.87. In terms of radiated interference in the near field, the improvement in attenuation of each norm achieved at least 2.81 times. The analysis of the characteristics in the far field showed that the use of the electromagnetic absorber allows reducing the transmission coefficient on average by 2.25 times at a distance of 1 m.

This paper focuses on the combination of the method of moments and the wire-grid approximation as an effective computational technique for modeling symmetrical antennas with low computational cost and accurate results. The criteria and conditions for the use of wire-grid surface approximation from various sources are presented together with new recommendations for modeling symmetrical antenna structures using the wire-grid approximation. These recommendations are used to calculate the characteristics of biconical and horn antennas at different frequencies. The results obtained using different grid and mesh settings are compared to those obtained analytically. Moreover, the results are compared to those obtained using the finite difference time domain numerical method, as well as the measured ones. All results are shown to be in a good agreement. The recommendations used for building a symmetrical wire-grid of those symmetrical antenna elements provided the most advantageous parameters of the grid and mesh settings and the wire radius, which are able to give quite accurate results with low computational cost. Additionally, the known equal area rule was modified for a rectangular grid form. The obtained radiation patterns of a conductive plate using both the original rule and the modified one are compared with the electrodynamic analysis results. It is shown that the use of the modified rule is more accurate when using a rectangle grid form.

With the growth of the radioelectronic complexity and the demand for cutting edge devices, the need to protect them and increase their reliability is also rising. There are many methods to provide this. Modal reservation is one of the most effective, reliable, and least complicated methods used nowadays. Using this method in tracing and mounting of printed circuit boards can guarantee both electromagnetic compatibility (by using modal filtering) and reliability (by using the cold redundancy) of the final electronic device. Modal reservation was proposed in 2015, and since then, massive research has been conducted on its investigations and development including 18 patents for inventions. Most of these studies have been devoted to modal reservation in terms of conducted emissions. However, up to now, a general and comprehensive review of modal reservation and investigations of its application with respect to radiated emissions has not been performed. Therefore, this paper aimed at presenting such a review on the history and recent research on modal reservation, concentrating on the studies related to radiated emissions. In addition, this paper analyzes current studies on the efficiency of using modal reservation under climatic impact.

This paper focuses on antenna modeling using wire-grid and surface triangulation as two of the most commonly used MoM-based approaches in this field. A comprehensive overview is provided for each of them, including their history, applications, and limitations. The mathematical background of these approaches is briefly presented. Two working algorithms were developed and described in detail, along with their implementations using acceleration techniques. The wire-grid-based algorithm enables modeling of arbitrary antenna solid structures using their equivalent grid of wires according to a specific modeling recommendation proposed in earlier work. On the other hand, the surface triangulation-based algorithm enables calculation of antenna characteristics using a novel excitation source model. Additionally, a new mesh generator based on the combined use of the considered algorithms is developed. These algorithms were used to estimate the characteristics of several antenna types with different levels of complexity. The algorithms computational complexities were also obtained. The results obtained using these algorithms were compared with those obtained using the finite difference time domain numerical method, as well as those calculated analytically and measured. The analysis and comparisons were performed on the example of a rectangle spiral, a spiral, rounded bow-tie planar antennas, biconical, and horn antennas. Furthermore, the validity of the proposed algorithms is verified using the Monte Carlo methodology.

The rapid advancement of telecommunication systems demands antennas with reduced mass and size. Wire-grid structures serve as effective alternatives to traditional solid metal antennas by significantly reducing their mass. The Optimal Current Grid Approximation recently proposed approach has introduced sparse wire-grid structures with further mass reduction but poses fabrication challenges, prompting modified approaches. However, the previously proposed modified approaches only focused on overcoming the difficulties in fabrication, without considering the current distribution, resulting in structures with characteristics different from those of the original wire-grid structure. To overcome these limitations, we propose the “Maximum Current-based” Optimal Current Grid Approximation, a novel approach that selectively reconnects wires with maximum current, improving the radiation performance of the sparse structure and aligning antenna characteristics more closely to those of the original wire-grid structure. Applied to a UHF-horn antenna, the sparse structures generated using the proposed approach were analyzed and their antenna characteristics were compared with those of the sparse structures obtained using other approaches and the original wire-grid structure, which in turn were compared with those from previous studies obtained numerically by different methods and experimentally for solid antenna prototypes. The performed comparative analysis confirmed that the proposed approach generates sparse wire-grid structures with antenna characteristics closer to those of the original wire-grid than other approaches, demonstrating its effectiveness. In addition, based on the simulation results, the sparse wire-grid structure is generated to verify the effectiveness of the proposed approach. The obtained experimental results demonstrate the effectiveness of the proposed approach in generating sparse wire-grid antenna with mass 1.41 times less than the original wire-grid antenna and 7.63 times less than the solid antenna while maintaining the required characteristics.