# On Modeling Antennas Using MoM-Based Algorithms: Wire-Grid versus Surface Triangulation
## 2 Materials and Methods
### Wire-Grid
#### 2.2.1 Wire-Grid: Overview
This approach depends on using mesh surfaces with strip-apertures that can have different forms and lead to changes in mesh configurations [71]. Similarly to lens and reflectors antennas, the researchers also used the wire-grid to analyze impulse radiating antenna [72]. Numerical methods revealed another important advantage in using the wire-grid approach not only as a designing technique but also as a modeling one. Various methods have been used to solve the problem of modeling the structure of wire-grid configuration. Then, researchers proposed to use this approach in modeling solid surfaces, since this can remarkably reduce the computational costs. Through their investigations, the researchers noticed that these resulting equivalent structures can be used not only in modeling but also in manufacturing. As an instance of such numerical methods, the conjugate gradient method (CGM) proved the possibility of using iterative techniques to solve electrically large arbitrarily oriented wire structures without storing any matrices as is conventionally done in direct methods [73]. In addition, the fast Fourier transform (FFT) was used to solve such problems especially with frequency selective aperture and patch periodic surfaces [74]. Moreover, in some works the researchers combined the previous two approaches (CGM-FFT) and effectively applied them to solve electromagnetic scattering [75; 76], radiation [77], and reflection properties [78] from/of grid of wires. On the other hand, the antenna or scattering problem from bodies of revolution (BOR) [79] has been solved regarding wire structures attached to the BOR [80] or in their presence [81], or a BOR of a wire-grid structure [82], and even rotational ones [83]. Furthermore, researchers have proposed many different numerical analyses of electromagnetic radiation [84; 85] and scattering [86; 87] properties of conducting wire-based bodies of arbitrary shapes. In particular, some models were used to analyze circular and square wire loops, circular and square plates, spherical and hemispherical conducting structures [88; 89; 90] and even dielectric structures [91; 92]. Researchers have also investigated other characteristics of such wire-grid structures like their radar cross section [93; 94], and the distribution of current and the driving-point impedance of a top-loaded antenna [95]. Numerical methods analysis of wire-grid structures has also enabled researchers to consider a wide range of different antenna types and shapes, for example, wire-grid microstrip antenna units [96; 97] and arrays [98]. Besides, they studied thin screens of periodical grids that may be used as an antenna radome [99], as well as the low-profile aircraft [100] and helicopter [101] antenna itself and its coupling modes [102]. Other than this, wire-grid approach was used in modeling vehicles with flush-mounted window antennas [103], spacecraft reflector antennas [104], and antennas with solar cells for low earth orbit satellite applications [105]. On the top of that, this approach was employed and experimentally validated on wire-grid ship models of different complexity at high frequencies [106; 107], and even on the model of aircraft at low ones [108]. A considerable attention has been paid by researchers to the wire-grid arrays [109]. Wire-grid can be used in designing and modeling microstrip arrays, which was proved numerically [110] and experimentally [111] even in the presence of dielectric [112]. In addition, the dipole arrays have also been investigated. For example, researchers presented what is called a super dense dipole array, which is a form of a sparse wire-grid [113]. They also used dipole arrays with FSS to design reconfigurable antennas [114]. They even used the wire-grid arrays in synthesizing tasks, for example, for forming the required radiation pattern of an adaptive antenna array to scan the atmosphere using small-element antennas in vertical sensing radars [115].