# Wire-Grid and Sparse MoM Antennas: Past Evolution, Present Implementation, and Future Possibilities
## 1 Introduction  
One current important trend in electronic technology is to take into account more rigorous system requirements in both commercial and military sectors while maintaining low manufacturing, operating, and maintenance costs. For example, the development of a system capable of working in real time through a special virtual network is relevant to the military sector. Moreover, designing antennas for both ground and onboard subsystems is a unique challenge, as they must be as simple and inexpensive as possible, while at the same time satisfying specific radiotechnical requirements. On the other hand, in the commercial sector, the development of wireless internet access systems, 5G wireless technologies, and the internet of things has led the market to develop low-cost antennas that meet bandwidth, gain, multiband performance, and physical constraints. These trends have prompted developers to create new methodologies and approaches to antenna design. After a long period of separate development of computer-aided design (CAD) systems for antennas and optimization methods, the most promising approach that allows for the identification of design problems and the construction of an optimal structure is the combined use of full-wave electromagnetic modeling and optimization methods. Specifically, the analysis of microwave integrated circuits and printed antennas can be time-consuming, which can lead to a highly inefficient design procedure that typically requires circuit analysis at every iteration of the design cycle, which in turn requires computationally efficient CAD. Thus, it is relevant to develop new methods for synthesizing antenna structures not only to optimize some geometric or physical variables, but also to create the shapes of the structures. These methods should allow for designing an optimal structure that satisfies all the requirements and constraints. Every decade or so, researchers try to review all the developments and advances in any scientific field. In our time, considerable reviews have been undertaken on modeling and manufacturing antennas and their technologies [1], especially on reconfigurable [2], smart [3], and wearable [4] antennas. In general, these reviews have a narrow focus. For example, this work has been undertaken on beam steering characteristics [5], liquid-based [6], microstrip [7], and switching technology [8] of reconfigurable, meta-wearable [9], smart [10], and transparent [11] antennas. In addition, some studies have been devoted to the design of these antennas where the state of art in designing MIMO [12], 5G [13], and even smart [14] and reconfigurable [15; 16] antennas is presented and provides a good database for any interested researcher in this field. However, a general overview of these studies is also helpful, Especially for new researchers. On the other hand, a huge amount of research has been undertaken on modeling antennas, especially those related to modeling wire grid and sparse antennas. Of particular interest are those studies that have used MoM in the past [17; 18; 19; 20; 21; 22] and today [23; 24; 25; 26; 27; 28], and even those that use other computational methods [29; 30; 31]. However, as we know, there exists no extensive general review on modeling wire-grid and sparse antennas using MoM. Therefore, the aim of this paper is to review the issues on modeling antennas using MoM and the main related aspects such as the computational, acceleration, and optimization-employed methods and the fields of their application. In addition, this paper aims to provide a possible future implementation of wire-grid and sparse antennas from the authors' point of view by presenting a new under research method to obtain effective wire sparse antennas. This paper is organized as follows. In the second section we concentrate on MoM and review the studies of other researchers related to this method and other computational methods. We try to reflect the reasons behind the relevance of investigating MoM.