# Pentaband Dual-Polarized Antenna for Multiservice Wireless Applications
## 2 Proposed Antenna Configuration and Description
### Single-Port Antenna Element  
Figure 2 illustrates the proposed geometry of the single-port antenna designed for pentaband resonance characteristics. The design includes an asymmetric truncated slot and a stepped aperture of different sizes at the quadrature position on the patch. By etching the asymmetric truncated slots on the patch, three resonance frequencies are  
Figure 1: Systematic representation of the design process. produced. Additionally, inserting an annular ring improves the bandwidth of the third band. To achieve pentaband performance, a stepped aperture configuration is etched on the top and left portion of the patch, and the slot is extended to the annular slot. It is essential to note that the proposed design's unique geometry is crucial in achieving pentaband resonance characteristics. The asymmetric truncated slots, stepped aperture configuration, and annular ring all work together to produce the desired frequency response. The geometry is designed on an FR-4 substrate with a relative permittivity of 4.4 and overall dimensions of 30 \(\times\) 30 \(\times\) 1.6 mm\({}^{3}\). A ground plane is located on the opposite side of the substrate to cover the entire substrate. Table 2 in this paper provides further information on the design parameters and their respective dimensions. The pentaband resonance approach achieves multiband operation by manipulating the current distribution on the patch antenna using different configurations of slots and apertures. The design process presented in Figure 3 demonstrates how this approach can be used to achieve five resonance frequencies in a single antenna. The design process begins with an initial step wherein a square patch is truncated asymmetrically to operate at the triple-resonance frequency, as shown in Figure 3a. This truncated patch is called Ant #1. In the second step, an annular ring slot is added to Ant #1 to modify the current distribution, resulting in a shift of the triple-resonance characteristics towards the lower-frequency side and dual resonances in the third band. The modified patch is called Ant #2, and it is shown in Figure 3b. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Parameter** & \(W_{s}\) & \(L_{s}\) & \(W_{p}\) & \(L_{p}\) & \(W_{p1}\) & \(L_{p1}\) & \(a\) & \(b\) & \(g\) \\ \hline Value (mm) & 30 & 30 & 12.5 & 11 & 12 & 8 & 4 & 6 & 0.5 \\ \hline Parameter & \(c\) & \(d\) & \(g_{1}\) & \(W_{s}\) & \(L_{s}\) & \(W_{s1}\) & \(L_{s1}\) & \(r_{it}\) & \(r_{out}\) \\ \hline Value (mm) & 8 & 7.5 & 1 & 1 & 2 & 3 & 3 & 2 & 3 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Geometrical parameters of the single-port antenna. Figure 2: Single-port pentaband antenna geometry. In the third step, Ant #2 is further modified by etching a stepped aperture configuration to form Ant #3, generating four resonance frequencies and shifting the lower two resonance bands further down. Figure 3c depicts Ant #3 after this step. Finally, in the last step, a fifth resonance band is added by creating another stepped aperture configuration in Ant #3, as shown in Figure 3d. This final design is the proposed pentaband antenna. In Figure 4a, the reflection coefficients obtained from the simulation for Ants #1 to #4 are shown. The reflection coefficient is a measure of how much energy is reflected back from the antenna, and it is related to the antenna's impedance. The resonance frequency of an antenna is the frequency at which the reflection parameter is minimum, indicating that the antenna is effectively matched to the transmission line. Ant #1 exhibits resonance frequencies at 2.4 GHz (2.38 GHz-2.45 GHz), 3.5 GHz (3.35 GHz-3.65 GHz), and 6.3 GHz (6 GHz-6.6 GHz), while Ant #2 operates at 2 GHz, 2.7 GHz, and 5.4 GHz bands. Ant #3 and Ant #4 exhibit 2 additional resonances at the higher-frequency side at 7.3 GHz and 8.4 GHz, with a slight shift in the lower 2 frequency bands.