# A Multi-Bandwidth Reconfigurable Patch Antenna for Devices in WLAN and UWB Technology Applications
## 2 Materials and Methods
### Development Stages  
Three iterations are needed to reach the final design of the antenna. They are shown in Figure 2. The changes that were introduced at each stage were chosen to reach the target reflection coefficient with a UWB and a WLAN band. The simulations were conducted using the Ansys(r) Electronics Desktop 2019 R3-High-Frequency Structure Simulator on a laptop equipped with an Intel Core i7-4710 MQ CPU running at 2.5 GHz and 8 GB of RAM.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Dimension** & **Size (mm)** & **Dimension** & **Size (mm)** & **Dimension** & **Size (mm)** \\ \hline \(h\) & 0.8 & \(k_{1}\) & 3 & \(W\) & 30 \\ \(D_{2}\) & 11.47 & \(D_{1}\) & 9.92 & \(K\) & 2 \\ \(l_{t1}\) & 2.6 & \(l_{t2}\) & 4 & \(R\) & 6 \\ \(l_{1}\) & 12 & \(l_{2}\) & 11.542 & \(a\) & 0.5 \\ \(l_{t}\) & 2 & \(d\) & 1.523 & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Dimensions in mm of the proposed antenna.  
Figure 1: Shape and dimensions of the proposed patch antenna (PA). (**a**) Front side of the PA antenna. (**b**) Back side of the PA antenna.  
Figure 2: Different developmental stages of the proposed antenna design. (**a**) First iteration. (**b**) Second iteration. (**c**) Proposed design.  
The initial iteration (Figure 2a) was a simple rounded rectangular patch antenna with a microstrip line feed. The radius (\(R\)) of the MP was calculated from the initiating patch frequency (\(F\)) in the following way [37,38]:  
\[R=\frac{F}{\sqrt{1+\left(\frac{2h}{\pi\epsilon_{r}F}\right)[\ln\left(\frac{\pi F }{2h}\right)+1.7720]}} \tag{1}\]  
\[F=\frac{8.791\times 10^{9}}{f_{r}\sqrt{\epsilon_{r}}} \tag{2}\]  
where \(\epsilon_{r}\) is the relative permittivity, \(h\) is the thickness of the substrate in cm, and \(f_{r}\) is the resonant frequency of the patch antenna in Hz.  
This first design does not have a band and shows a constant reflection coefficient (Figure 3, _Iteration 1_).  
For the second iteration (Figure 2b), the antenna was modified by adding the SCP and the RP with semicircular slots, including two rectangular slots placed strategically to improve the impedance matching and increase the operating bandwidth. In this iteration, the performance, considering the desired operating bands, was significantly improved. This design has a bandwidth of 1.21 GHz with a return loss up to \(-\)31.9 dB. The new shape enables the wideband operation from 3.87 GHz to 4.68 GHz (Figure 3, _Iteration 2_). However, the antenna still does not meet the requirements of the bands.  
To further improve the antenna matching and widen the operating band to cover the band requirements, the patch is further modified (Figure 2c). A rounded rectangular patch is placed with a single feed, which is connected to the rectangular and semicircular patches with two rectangular slots. The semicircular and rectangular patches are positioned at the ground plane layer in parallel to the rounded rectangle patch as a slot. This iteration gives the desired UWB and WLAN bands with an increased operating bandwidth to cover frequency bands for planned wireless communication applications. In the simulation of this iteration, the antenna has--in the WLAN band--a low-UWB characteristic that covers the frequency bands (2.3-2.6 and 3.7-5.4 GHz); the two resonance frequencies are at 2.5 GHz and 4.4 GHz, with a return loss of \(-\)31.9 dB and \(-\)34.9 dB, respectively, and a gain that exceeds 4.29 dB (Figure 3, _Proposed Design_).  
Figure 3: Proposed antenna reflection coefficients for different development stages.